2013 Canadian Exposure Factors Handbook
Life Expectancy, Body Dimensions,
Inhalation, Time-Activity, and Soil Ingestion
G. Mark Richardson, Ph.D.
and
Stantec Consulting Ltd.
© G. Mark Richardson and Stantec Consulting Ltd., 2013
Lead Author:
G. Mark Richardson, PhD.
Support:
■■ Stantec Consulting Ltd.
Suite 400, 1331 Clyde Ave., Ottawa, ON K2C 3G4
■■ NSERC CREATE HERA Program and the Interdisciplinary Toxicology Program
Toxicology Centre, University of Saskatchewan,
44 Campus Drive, Saskatoon, SK S7N 5B7
Edited by Joanne Sanche
Designed by Erik Christopher
Disclaimer
The analyses and statistics presented in this handbook are based on Public Use Microdata Files and other
data sets from a variety of Statistics Canada surveys, including the 2000 (Cycle 1.1) to 2010 Canadian Community Health Surveys, the 2005 and 2010 General Social Surveys (cycles 19 and 24, respectively), and the
2007 Canadian Health Measures Survey. These data sets contain anonymized data. Lead author G. Mark
Richardson of Stantec Consulting prepared all computations on these data, and he is solely responsible for
the use and interpretation of these data.
The analyses and evaluations used to derive the various statistics presented herein were conducted in a
manner consistent with the level of skill and care ordinarily exercised by professional scientists practising
under similar conditions. Stantec Consulting Ltd. and G. Mark Richardson make no warranties with respect
to the use of these data and information for purposes of risk assessment or any other purpose. The use of the
results and recommendations presented herein to conduct risk assessments, to develop probability density
distributions for human exposure factors and/or other summary statistics, and the subsequent interpretation
of chemical exposures and risks based on any aspect(s) of the data and information contained herein, are
solely the responsibility of the individuals, firms, and/or agencies conducting those exposure and risk assessments.
The listing or mention of any corporation, company, or product does not constitute endorsement, approval,
or recommendation by Stantec Consulting Ltd. or G. Mark Richardson.
For more information, please contact:
G. Mark Richardson
Stantec Consulting Ltd.
Suite 400, 1331 Clyde Ave.
Ottawa, Ontario CANADA
K2C 3G4
Email: mark.richardson@stantec.com
Suggested Citation:
GM Richardson and Stantec Consulting Ltd. (2013). 2013 Canadian Exposure Factors Handbook. Toxicology Centre, University of Saskatchewan, Saskatoon, SK CANADA. Available at: www.usask.ca/toxicology
About Stantec Consulting Ltd.
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are also committed to ensuring that the latest science and tools are readily available to its own Environmental Sciences Group and to the broader environmental regulatory and risk assessment communities across
Canada. For this reason, Stantec is pleased to collaborate with the University of Saskatchewan’s Toxicology
Centre and their NSERC Collaborative Research and Training Experience program in Human and Ecological Risk Assessment (CREATE HERA) to make available the 2013 Canadian Exposure Factors Handbook.
About the Author
G. Mark Richardson, Ph.D., is the author of the 1997 Compendium of Canadian Human Exposure Factors
for Risk Assessment. Prior to joining Stantec Consulting Ltd., Dr. Richardson was Chief of the Contaminated Sites Division, Environmental Health Bureau, Health Canada, where he was responsible for establishing
and directing Health Canada’s Expert Support program to the Federal Contaminated Sites Action Plan
(FCSAP). In that role he authored and co-authored national approaches and methods for the assessment of
human health risks presented by contaminated sites in Canada.
About the Toxicology Centre at the
University of Saskatchewan
Toxicology deals with the harmful effects of chemical and physical agents on living organisms and biological systems. The Toxicology Centre at the University of Saskatchewan is Canada’s leading interdisciplinary
toxicology centre and is the only one in Western Canada. It coordinates, delivers, and governs the Interdisciplinary Toxicology Undergraduate and Graduate Programs and facilitates collaborative, interdisciplinary
research among faculty and external stakeholders. The Toxicology Undergraduate Program is the only
undergraduate program in Western Canada that leads to a B.Sc. in Toxicology. The Toxicology Graduate
Program offers M.Sc. and Ph.D. programs within an array of toxicology sub-disciplines, such as biomedical
and human health toxicology, analytical and forensic toxicology, aquatic and ecotoxicology, radiation and
radionuclide toxicology, biochemical and molecular toxicology, and veterinary and wildlife toxicology. The
Toxicology Centre houses state-of-the-art analytical and experimental facilities suited for a wide variety
of toxicology research projects. Analytical laboratories are equipped for analysis of organic and inorganic
contaminants and a range of physiological, biochemical, and molecular endpoints. Experimental facilities
are exemplified by the Aquatic Toxicology Research Facility (ATRF), the only facility of its type in Canada,
where researchers study the adverse effects of contaminants and other stressors on aquatic organisms and
model aquatic ecosystems. Additional animal research facilities are accessible elsewhere on campus.
About CREATE HERA
Canadians face an ever-increasing number of potential health risks from environmental contaminants. Government scientists and the public need to know the dangers that contaminated soil, water, air, foodstuffs, and
consumer products pose to humans and the ecosystem and how to manage these risks to protect human and
ecological health. In response, an outstanding group of Canadian experts have developed the NSERC Collaborative Research and Training Experience program in Human and Ecological Risk Assessment (CREATE HERA). Housed within the U of S Toxicology Centre, this national, multidisciplinary program trains
students to assess the public health and ecological risks posed by contaminants in our environment. The
CREATE HERA program will produce a new class of professionals who understand the entire process of
risk assessment and management. It is also the first training program to explore Canada’s laws and regulations and the role of risk assessors within that Canadian legal framework.
Contents
List of Tables
List of Figures
PREFACE
1.0 INTRODUCTION
1.1 References
2.0 RELEVANT CANADIAN DATA
2.1 About the Data
3.0 AGE GROUPS OF THE CANADIAN POPULATION
3.1 Infants
3.2 Toddlers and Children
3.3 Teens, Adults, and Seniors
3.4 References
4.0 LIFE DURATION: AVERAGE LIFE EXPECTANCY VERSUS AVERAGE AGE AT DEATH
4.1 References
5.0 BODY WEIGHT
5.1 Erratum from Richardson (1997)
5.2 Mean Body Weight is Increasing in the Canadian Population
5.3 Self-Reported versus Measured Body Weight
5.4 Infant and Toddler Body Weight
5.5 Conclusions
5.6 References
6.0 INHALATION RATES
6.1 General Population
6.2 Construction and Utility Workers
6.3 References
7.0 SKIN SURFACE AREA
7.1 References
8.0 TIME-ACTIVITY
8.1 Time Spent Indoors versus Outdoors
8.2 Time Spent Washing and Bathing
8.3 Time Spent Indoors at Home Awake
8.4 References
9.0 SOIL INGESTION RATES
9.1 Overview
9.2 Conclusions
9.3 References
10.0 NEW DATA — 1997 AGE GROUPS
10.1 References
List of Tables
Table 2.1 Summary of Statistics Canada surveys and relevant data used to update exposure factors in this
handbook
Table 3.1 Age groups and ranges, as defined in other sources and in this handbook
Table 4.1 Average life expectancy and age at death in Canada
Table 5.1 Summary of recent Statistics Canada surveys on measured body weight, by age group and gender
Table 5.2 Recommended body weight (kg), by age group (years) and gender
Table 6.1 Recommended inhalation rate (m3/day), by age (years) and gender
Table 7.1 Equations established by U.S. EPA (1995) to estimate body surface area (m2) from data on height
(cm) and weight (kg)
Table 7.2 Skin surface area (m2) for total body and various parts, by age group and gender
Table 7.3 Surface area for various body parts as a percentage of total body surface area and compared to
Boliol et al. (2008)
Table 8.1 Time-activity factors (minutes/day), by age group and gender
Table 8.2 Percent of surveyed population reporting spending all (100%) of their day indoors or none (0%)
of their day outdoors, by age and gender
Table 9.1 Soil ingestion rate assumptions (mg/day) used by various Canadian environmental regulatory
agencies
Table 9.2 Comparison of dust and soil ingestion rate estimates (mg/day) based on mechanistic studies derived by Wilson et al. (2013) and Ozkaynak et al. (2011); results from Stenek et al. (2012), from reanalysis
of tracer studies, added for comparison
Table 10.1 Revised exposure factors for Infant, Toddler, and Child age groups, using age ranges defined in
the 1997 Compendium (Richardson 1997)
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2013 Canadian Exposure Factors Handbook
List of Figures
Figure 3.1 Percentage of Canadian mothers breastfeeding for >6 months.
Figure 5.1 Mean body weight for infants aged 6 to 11 months, sexes combined, by survey year.
Figure 5.2 Mean body weight for toddlers aged 1 to <4 years, sexes combined, by survey year.
Figure 5.3 Mean measured body weight by age group and year of survey, sexes combined.
Figure 5.4 Measured versus self-reported body weight.
Figure 7.1 Mean infant height by year of U.S. NHANES survey.
Figure 7.2 Measured versus self-reported height.
Figure 8.1 Average reported time spent at indoor sedentary activities, by year of CCH Survey.
Figure 8.2 Time (min/day) spent at “other outdoor activities,” for all ages (≥15 years) and sexes combined.
2013 Canadian Exposure Factors Handbook
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PREFACE
Risk assessments conducted in Canada for Canadians should use data and assumptions that reflect the Canadian population. The Compendium of Canadian Human Exposure Factors for Risk Assessment (Richardson
1997) was published to do just that, providing Canadian population data and information for human health
risk assessments in this country. The 1997 Compendium has been the most common source of receptor
characteristics for contaminated site (and other) risk assessments in Canada. It is cited in various provincial
and federal environmental regulations, regulatory risk assessment guidance, protocols for the derivation of
risk-based environmental quality guidelines, and in technical documents for individual risk-based environmental guidelines and risk assessments. However, it is now significantly out of date. In response, Stantec
Consulting has supported and funded the creation of the 2013 Canadian Exposure Factors Handbook,
which is intended to replace the 1997 Compendium.
Stantec is making this handbook available to the risk assessment and regulatory communities in Canada.
The goal is to protect the Canadian population exposed to environmental contaminants by ensuring that risk
assessments are as relevant as possible.
This handbook includes data accessed from the following recent Statistics Canada surveys:
■■ The 2000 to 2010 Canadian Community Health Surveys,
■■ The 2005 and 2010 General Social Surveys (Cycles 19 and 24), and
■■ The 2007 Canadian Health Measures Survey.
This handbook updates the age ranges for the various population subgroups used in risk assessments. The
changes are as follows:
■■ Infant, traditionally defined as 0 to 6 months to reflect the period of breastfeeding, is now defined as <1 year (i.e., ≤ 11 months), reflecting that over 40%
of Canadian mothers now breastfeed for longer than 6 months.
■■ Toddler, traditionally defined as 7 months to 4 years (7 months to <5 years),
is now defined as 1 to <4 years; the beginning of this range now more accurately reflects the age at which walking begins, and the changes also correspond to the changes to the age ranges for infant and child.
■■ Child, traditionally defined as 5 to 11 years (5 to <12 years) to reflect the
elementary school experience, is now defined as 4 to <12 years; this change
reflects that formal education in Canada now typically begins with junior kindergarten at age 4.
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2013 Canadian Exposure Factors Handbook
■■ Teen remains defined as 12 to <20 years.
■■ Adult is now defined as 20 to <65 years, reflecting the change in the definition of senior.
■■ Senior, defined in the 1997 Compendium as ≥60 years, is now defined as ≥65
years, reflecting the institutional definition of senior in Canada.
The following are other major changes from the 1997 Compendium that are included in this handbook:
■■ Average body weights for children, teens, adults, and seniors have been increased by 2% to 11%, depending on age and gender group.
■■ Average body weight for infants has decreased by 1.2%, while average body
weight for male toddlers has decreased by 4.2% and for female toddlers by
9.8% (7.3% for sexes combined). These changes were made to correct a mistaken adjustment to infant and toddler weights in the 1997 Compendium,
where it was assumed these groups had increased in weight over time as observed for older age groups. That adjustment can now be demonstrated to be
in error: average body weights for infants and toddlers have in fact remained
constant over time.
■■ Inhalation rates have been changed to reflect a 2008 Canadian analysis.
■■ Skin surface areas have been revised for each age group to reflect the most recent data on body weight and height, from which skin surface area is derived.
■■ Time-activity data have been significantly updated to reflect the increasing
time spent by teens, adults, and seniors at indoor sedentary activities associated with use of computers, the Internet, video games, etc.
■■ Time-activity data have been augmented with additional variables to better
quantify the time spent indoors and outdoors at home, and time spent indoors
and outdoors at locations away from the home.
■■ Soil ingestion rates have been introduced, which reflect the ongoing research,
both national and international, that indicates that soil ingestion is significantly over-estimated with existing assumptions used by federal and provincial
agencies in Canada.
The data and information presented herein are necessarily condensed and summarized. However, more
explicit and detailed information is available on numerous specific exposure factors and for specific geographic regions. Contact Stantec Consulting or the author to discuss your data and information needs.
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2013 Canadian Exposure Factors Handbook
1.0 INTRODUCTION
To accurately assess human health risk posed by exposure to environmental contaminants, scientists require
current data on various factors, including body weights, inhalation rates, and time-activity patterns (e.g.,
time spent indoors versus outdoors). Risk assessments conducted in Canada for Canadians require current
data on these and other factors that reflect the Canadian population. However, unlike the U.S., where the
Environmental Protection Agency regularly compiles and publishes exposure factors for risk assessment
(see U.S. EPA 2008, 2011), no regulatory agency in Canada compiles or updates this type of information.
To provide this needed information in one place, the Compendium of Canadian Human Exposure Factors
for Risk Assessment (Richardson 1997; referred to herein as the “1997 Compendium”) was published and
has been a valuable resource for Canadian risk assessors.
The 1997 Compendium is now dated: some of the exposure factors presented in it were based on data from
Canadian surveys that have since been repeated. The data and statistics presented in this 2013 Canadian
Exposure Factors Handbook are based on current surveys that better reflect current Canadian population
characteristics, behaviours, and activities; therefore, this handbook is meant to replace the 1997 Compendium. Its goal is to provide an accessible, up-to-date resource for Canadian risk assessors and environmental
regulatory agencies, ensuring that human health risk assessments are relevant, accurate, and as free of uncertainty as possible.
1.1 References
U.S. EPA (U.S. Environmental Protection Agency). 2008. Child-Specific Exposure Factors Handbook (Final Report) 2008. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/096F.
U.S. EPA (U.S. Environmental Protection Agency). 2011. Exposure Factors Handbook 2011 Edition (Final). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/052F.
Richardson, GM. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment. O’Connor Associates Environmental Inc.: Ottawa, ON.
2013 Canadian Exposure Factors Handbook
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2.0 RELEVANT CANADIAN DATA
Statistics Canada is the primary source of data on the Canadian population, conducting numerous surveys
on virtually all aspects of Canadian life. Survey respondents are a statistically representative sample of the
Canadian population. Further information on Statistics Canada surveys can be found at www.statcan.gc.ca.
Data from the following Statistics Canada surveys were used in this handbook:
■■ The Canadian Community Health Survey (CCHS). Since 2000, Statistics
Canada has regularly gathered health-related data through this survey. In this
survey series, data of particular interest to risk assessors include respondents’
weight, height, and food and beverage consumption (both frequency of consumption and quantities consumed).
■■ The General Social Survey (GSS). Initiated by Statistics Canada in 1985,
the GSS gathers data on social trends. Of particular interest for this handbook
are data from the 2010 GSS survey on time use (Cycle 24).
■■ The Canadian Health Measures Survey (CHMS). Conducted between
2007 and 2009 in association with Health Canada, the CHMS collected additional data on weight, height, and other parameters relevant to risk assessment.
Table 2.1 summarizes the Statistics Canada surveys, sample sizes, and relevant data used to update the human exposure factors presented in this handbook.
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2013 Canadian Exposure Factors Handbook
Table 2.1 Summary of Statistics Canada surveys and relevant data used to update exposure factors in this handbook
Survey
Year(s)
Sample
Size
Relevant Data
Primary Data Sets
GSS
Cycle 24
CCHS
Cycle 2.2
CCHS
Cycle 3.1
CCHS
2009-2010
2010
15,390
2004
35,107
2005
132,211
2009-2010
124,188
CHMS
Cycle 1
2007
5,604
Age; sex; province of residence; time-activity patterns; age restricted to Canadians ≥15 years of age.
Age; sex; province of residence; measured body weight and height; 24-hour
food recall survey; included toddlers as young as 1 year of age.
Age; sex; province of residence; measured body weight and height (as part of
Sub-Sample 2; n=4,735); age restricted to Canadians ≥12 years of age.
Age; sex; province of residence; duration of breastfeeding last child; average
daily frequency of consumption of carrots, fruit, fruit juice, potatoes, green
salad, total fruits and vegetables, other vegetables; time spent at sedentary
activities; age restricted to Canadians ≥12 years of age.
Age; sex; province of residence; height (measured and self-reported); weight
(measured and self-reported); frequency of consumption of: meat and fish,
milk and dairy, grains, fruits and vegetables, fats; frequency of consumption
of water and soft drinks; duration of breastfeeding last child; age restricted to
Canadians ≥6 years of age.
Secondary Data Sets (used primarily to demonstrate trends in variables with time)
CCHS
2000-2001
130,880
Age; sex; province of residence; duration of breastfeeding last child; average
Cycle 1.1
daily frequency of consumption of carrots, fruit, fruit juice, potatoes, green
salad, total fruits and vegetables, other vegetables; time spent at sedentary
activities.
CCHS
2003
134,072
Age; sex; province of residence; duration of breastfeeding last child; average
Cycle 2.1
daily frequency of consumption of carrots, fruit, fruit juice, potatoes, green
salad, total fruits and vegetables, other vegetables; time spent at sedentary
activities.
CCHS
2004
35,107
Age; sex; province of residence; duration of breastfeeding last child; average
Cycle 2.2
daily frequency of consumption of carrots, fruit, fruit juice, potatoes, green
salad, total fruits and vegetables, other vegetables; time spent at sedentary
activities.
CCHS
2005
132,221
Age; sex; province of residence; duration of breastfeeding last child; average
Cycle 3.1
daily frequency of consumption of carrots, fruit, fruit juice, potatoes, green
salad, total fruits and vegetables, other vegetables; time at sedentary activities.
CCHS
2007-2008
131,061
Age; sex; province of residence; duration of breastfeeding last child; average
2007-2008
daily frequency of consumption of: carrots, fruit, fruit juice, potatoes, green
salad, total fruits and vegetables, other vegetables; time spent at sedentary
activities.
2013 Canadian Exposure Factors Handbook
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2.1 About the Data
Statistics Canada provides data in one of two ways: through their public use microdata files (PUMF) and
through secure data portals housed at various universities across Canada. The PUMF collection is openly
distributed by Statistics Canada and includes microdata and documentation for most of the Statistics Canada surveys. However, for some surveys, such as the CHMS, data must be accessed through a secure data
portal. For this handbook, secure data were accessed at the Saskatchewan Research Data Centre (SKY
RDC, University of Saskatchewan, Saskatoon, SK). Contact Statistics Canada (infostats@statcan.gc.ca) to
obtain a PUMF or to arrange access to a secure data portal.
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2013 Canadian Exposure Factors Handbook
3.0 AGE GROUPS OF THE
CANADIAN POPULATION
Exposure and risk assessments in Canada routinely consider the following 5 age groups, which were introduced by Health Canada in 1994 based on work prepared in 1988:
■■ Infant: 0 to 6 months,
■■ Toddler: 7 months to 4 years (interpreted as 7 months to <5 years),
■■ Child: 5 to 11 years (interpreted as 5 to <12 years),
■■ Teen: 12 to 19 years (interpreted as 12 to <20 years), and
■■ Adult: 20+ years.
Health Canada (2012) and the Canadian Council of Ministers of Environment (CCME 2006) have prescribed deterministic (average value) assumptions for a variety of exposure factors for these age groups.
Age groups are assessed separately because each has varying potential for exposure to environmental contaminants (HC 1994). For example, most infants are exposed to substances via breast milk; toddlers are exposed to contaminants in soil more so than other age groups; and adults may use certain consumer products
that could expose them to various chemicals and contaminants.
The above age groups were maintained in subsequent Health Canada risk assessment guidance (HC 2012,
2010a,b) and in the 2006 CCME protocol for derivation of soil quality guidelines. The 1997 Compendium
also used these age groups, but redefined adult as 20 to <60 years and added the senior age group, defined
as ≥60 years of age.
These age groupings, however, are revised within this handbook (Table 3.1). Explanations for these revisions are provided in the following sections.
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Table 3.1 Age groups and ranges, as defined in other sources and in this handbook
Age Range
HC (1994, 2012, 2010a,b),
Age Group
CCME (2006)
Richardson (1997)
This handbook
0 to 6 months
0 to 6 months
<1 year a
7 months to <5 years
7 months to <5 years
1 to <4 years b
Child
Teen
Adult
5 to <12 years
12 to <20 years
≥20 years
5 to <12 years
12 to <20 years
20 to <60 years
4 to <12 years c
12 to <20 years d
20 to <65 years e
Senior
-- f
≥60 years
≥65 years
Infant
Toddler
a Interpret as up to 11 months.
b Interpret as from 1 year to 3 years and 11 months.
c Interpret as from 1 year to 3 years and 11 months.
d Interpret at from 12 years to 19 years and 11 months.
e Interpret as from 20 years to 64 years and 11 months.
f Not defined.
3.1 Infants
This handbook redefines infants as <1 year of age (interpreted as up to and including 11 months). This age
group was originally defined as 0 to 6 months based on the perceived average duration of breastfeeding at
the time (HC 1988, 1994). This definition is revised herein because recent data show that a large proportion
of infants are now breastfed for longer than 6 months (Figure 3.1). Since 2000, Statistics Canada has consistently surveyed mothers on the duration of breastfeeding their last child, and the proportion of mothers that
breastfeed their infants beyond 6 months is increasing. For the 2009-2010 survey period, >40% of mothers
reported breastfeeding for more than 6 months, with >16% reporting breastfeeding for more than 1 year.
Infancy ends when the toddler age group intuitively begins: with independent walking, which usually occurs at or around 1 year of age.
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2013 Canadian Exposure Factors Handbook
Figure 3.1 Percentage of Canadian mothers breastfeeding for >6 months (Data from Statistics Canada CCH Surveys; various years).
3.2 Toddlers and Children
The beginning of toddlerhood is usually associated with the onset of independent walking. Infants begin to
stand and walk along furniture (i.e., toddle) at 10 to 12 months of age and to walk independently at 12 to 15
months of age. Therefore, it is inaccurate to define the toddler age group as beginning at 7 months of age, as
per Health Canada (1994, 2010a,b, 2012) and Richardson (1997). Thus, this handbook defines the toddler
age group as beginning at 1 year of age.
The beginning of the child age range was originally defined as the age when a child begins to experience
extended periods in environments outside of the home, particularly institutional education. The increasing
proportion of two-income families and the subsequent advent of junior kindergarten programs and full-time
daycare programs dramatically alter the previous assumptions made by Health Canada (1988, 1994) about
when children begin institutionalized programs. Thus, the child age group has been redefined herein to begin at 4 years of age (the start of junior kindergarten).
2013 Canadian Exposure Factors Handbook
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As a result of these considerations, the toddler age range now spans from 1 year to 3 years and 11 months
of age (1 to <4 years), and the child age range now spans from 4 years to 11 years and 11 months of age (4
to <12 years).
3.3 Teens, Adults, and Seniors
The teen age group has been retained as previously defined, spanning 12 through 19 years and 11 months
of age (i.e., teen = 12 to <20 years).
The onset of adulthood at 20 years of age has been retained consistent with the 1997 Compendium, CCME
(2006), and Health Canada (2010a,b, 2012). However, the adult age group has been revised to include persons up to 64 years and 11 months of age (i.e., adult = 20 to <65 years), reflecting the revised definition for
senior Canadians.
Seniors are now specifically and institutionally defined in Canada as people ≥65 years of age (Turcotte and
Schellenberg 2006), not ≥60 years as defined in the 1997 Compendium. Therefore, seniors have been redefined herein as ≥65 years of age.
3.4 References
CCME (Canadian Council of Ministers of Environment). 2006. A Protocol for the Derivation of Environmental and Human Health Soil Quality Guidelines. CCME, Winnipeg, MB.
HC (Health Canada). 1988. DRAFT – Reference Values for Canadian Populations. Working Group on Reference Values, Environmental Health Directorate, Health Canada, Ottawa, ON. Dated July 4, 1988.
HC (Health Canada). 1994. Human Health Risk Assessment for Priority Substances. Priority Substances
List assessment report. Health Canada, Ottawa, ON. Cat. No. En40-215/41E
HC (Health Canada). 2010a. Federal Contaminated Site Risk Assessment in Canada Part VI: Guidance on
Human Health Detailed Quantitative Risk Assessment for Chemicals (DQRAChem). Contaminated Sites
Program, Health Canada, Ottawa, ON. Available by contacting Health Canada at: http://www.hc-sc.gc.ca/
ewh-semt/pubs/contamsite/chem-chim/index-eng.php
HC (Health Canada). 2010b. Federal Contaminated Site Risk Assessment in Canada Part VI: Guidance
on Human Health Detailed Quantitative Radiological Risk Assessment (DQRARad). Contaminated Sites
Program, Health Canada, Ottawa, ON. Available by contacting Health Canada at: http://www.hc-sc.gc.ca/
ewh-semt/pubs/contamsite/huma_health-sante/index-eng.php
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2013 Canadian Exposure Factors Handbook
HC (Health Canada). 2012. Federal Contaminated Site Risk Assessment in Canada Part I: Guidance on Human Health Preliminary Quantitative Risk Assessment (PQRA), version 2.0. Contaminated Sites Program,
Health Canada, Ottawa, ON. Online at: http://www.hc-sc.gc.ca/ewh-semt/pubs/contamsite/part-partie_i/
index-eng.php
Richardson, GM. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment. O’Connor Associates Environmental Inc., Ottawa, ON.
Turcotte M and G Schellenberg. 2006. A Portrait of Seniors. Statistics Canada, Ottawa, ON. Catalogue no.
89-519-XIE.
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4.0 LIFE DURATION: AVERAGE LIFE
EXPECTANCY VERSUS
AVERAGE AGE AT DEATH
Duration of life is a common assumption used in risk assessment, particularly when assessing exposure to
and risks from carcinogens. Assessors require an amortization (averaging) period to derive lifetime average
daily dose or intake. Health Canada (2004) recommended 75 years as average life duration. This meant
that if exposed to a carcinogenic substance for all or part of a hypothetical person’s life, that exposure was
amortized (averaged) over 75 years. Health Canada provided no rationale for this assumption. Recently,
Health Canada (2010, 2012) has extended assumed life duration to 80 years; again, however, no rationale
was provided for this assumption.
Two statistics are available to define average life duration: average life expectancy, and average age at
death. Although obviously related, these statistics are not identical, as is demonstrated in Table 4.1.
Table 4.1 Average life expectancy and age at death in Canada
Life expectancy (years)
From birth a,b
From age 65 a,b
Year
Age at death c
(years)
1990
-- d
--
70.9
1996-1998
78.6
83.2
--
1998-2000
79.0
83.5
--
2000-2002
79.6
83.9
--
2002-2004
80.0
84.2
--
2004-2006
80.5
84.7
--
2005
--
--
74.2
2006-2008
80.9
85.0
--
a Source: Statistics Canada (2012)
b Source: Statistics Canada (2011)
c Source: Statistics Canada (2008)
d “-- ” = no data
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2013 Canadian Exposure Factors Handbook
Statistics on average life expectancy are more readily available. These are generally based on data spanning
a 3-year period, and they predict the average age to which an infant born in the designated 3-year period will
survive. Also typically provided is the age to which a person 65 years of age (in the designated time period)
will survive. Those already 65 years of age are consistently predicted to survive to a greater age on average
than newborn infants (see Table 4.1).
Data on average age at death are much less available; Canadian data could be located for only 2 years (1990
and 2005). These statistics reflect the average age at death of individuals who died in the specified years.
Between 1990 and 2005, the average age of death increased by 3.3 years. Extrapolating linearly, the average
age at death in Canada for 2012 might be approximately 76 years and average age at death in 2086, 92 years.
However, data from Statistics Canada could not be located to confirm this simple extrapolation.
The difference between estimated life expectancy and average age at death relates to the year for which
these statistics are defined. The average age at death is defined for the year(s) in which statistics are available (1990 and 2005, for example). However, average life expectancy projects into the future; in other
words, the anticipated average age of death in 2082 to 2084 (for infants born in 2002 to 2004) would be 80
years of age.
For purposes of amortization in Canadian risk assessments, it is recommended herein that average duration
of life be defined as 80 years. This assumption would particularly apply to newborns and young children
being considered as receptors within risk assessments. For older age groups, average life expectancy approaches, if not exceeds, 80 years. Because lifetime average daily dose calculations would be greater for
shorter life duration assumptions, any error introduced for adults and seniors by assuming an 80-year lifespan—rather than, say an 85-year lifespan—would be conservative and would not lead to an under-estimate
of exposure and risk.
4.1 References
HC (Health Canada). 2004. Federal Contaminated Site Risk Assessment in Canada Part I: Guidance on
Human Health Preliminary Quantitative Risk Assessment (PQRA). Contaminated Sites Program, Health
Canada, Ottawa, ON.
HC (Health Canada). 2010. Federal Contaminated Site Risk Assessment in Canada Part VI: Guidance on
Human Health Detailed Quantitative Risk Assessment for Chemicals (DQRAChem). Contaminated Sites
Program, Health Canada, Ottawa, ON. Available by contacting Health Canada at: cs-sc@hc-sc.gc.ca
2013 Canadian Exposure Factors Handbook
15
HC (Health Canada). 2012. Federal Contaminated Site Risk Assessment in Canada Part I: Guidance on Human Health Preliminary Quantitative Risk Assessment (PQRA), version 2.0. Contaminated Sites Program,
Health Canada, Ottawa, ON. Online at: http://www.hc-sc.gc.ca/ewh-semt/pubs/contamsite/part-partie_i/
index-eng.php
Statistics Canada. 2008. The Daily, dated January 14, 2008. Statistics Canada, Ottawa, ON. Catalogue no.
11-001-XIE
Statistics Canada. 2011. Deaths–2008. Health Statistics Division, Statistics Canada, Ottawa, ON. Catalogue
no. 84F0211X.
Statistics Canada. 2012. Table 102-0512–Life expectancy, at birth and at age 65, by sex, Canada, provinces and territories, annual (years), CANSIM (database). Accessed February 13, 2012. Available online at:
http://www5.statcan.gc.ca/cansim/a26?lang=eng&retrLang=eng&id=1020512&paSer=&pattern=&stByVal=2&p1=-1&p2=37&tabMode=dataTable&csid=
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5.0 BODY WEIGHT
Body weight is a key exposure factor for risk assessment. Estimates of exposure to environmental contaminants are standardized on the basis of per unit body weight. Table 5.1 presents recent Statistics Canada
findings on measured body weight, by age and gender groupings.
Table 5.1 Summary of recent Statistics Canada surveys on measured body weight, by age
group and gender a
CCHS, cycle 2.2 (2004)
Age Group
and Gender
Mean body weight
b
Infant
Toddler
Female
Male
Combined
Child
Female
Male
Combined
Teen
Female
Male
Combined
Adult
Female
Male
Combined
Senior
Female
Male
Combined
(kg) and SD
N
c
--
--
14.84 ± 2.32
15.91 ± 2.56
15.38 ± 2.50
389
393
782
CCHS, cycle 3.1 (2005)
d
Mean body weight
(kg) and SD
N
--
--
--
--
--
--
37.12 ± 15.29
37.87 ± 16.12
37.50 ± 15.72
2555
2615
5170
61.49 ± 13.31
70.89 ± 16.53
66.04 ± 15.67
1702
1597
3299
58.57 ± 13.88
66.39 ± 19.18
62.61 ± 17.26
301
321
622
71.74 ± 16.79
84.80 ± 16.02
77.53 ± 17.69
4744
3775
8519
69.88 ± 16.40
84.21 ± 15.28
76.63 ± 17.42
1594
1421
3015
68.08 ± 13.63
81.12 ± 14.11
72.83 ± 15.17
2111
1208
3319
67.50 ± 13.65
81.94 ± 13.91
73.23 ± 15.46
609
401
1010
a Statistics for survey populations only.
b Age groups as defined for this handbook in Table 3.1.
c SD = standard deviation.
d N = sample size.
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5.1 Erratum from Richardson (1997)
In the 1997 Compendium, an error was made in the delineation of mean body weight for infants (0 to
6 months) and toddlers (7 months to <5 years). At that time, the only Canadian data on body weights available for these age groups was the Nutrition Canada Survey (NCS) of 1970-72. The 1997 Compendium noted
that, for older age groups, mean body weight had increased between 1970-72 and 1988, the latter year relating to the data of the Canadian Fitness and Lifestyle Research Institute (CFLRI 1988; Stephenson and Craig
1990). Lacking any data to the contrary, and assuming that weight gain over time would also be observed in
the youngest age groups, the 1997 Compendium adjusted the NCS-calculated mean body weight for infants
and toddlers using the same proportional increase observed for children (i.e., female weight increased by
17.8%; male weight, 14.3%; and sexes combined, 15.9%).
However, the assumption that average body weight had increased in infants and toddlers is now known to
be wrong. Although older age groups have experienced a progressive gain in average body weight over
the past 3 to 4 decades (Figure 5.1), the same is not true for infants and toddlers (Portier et al. 2007). Data
from the U.S. population (Canadian patterns are assumed to be the same) show that the mean body weight
of infants <1 year (Figure 5.1) and toddlers aged 1 to <4 years (Figure 5.2) have remained relatively constant over time. As a result, the mean body weights proposed in the 1997 Compendium were erroneously
increased by approximately 15% above the values determined from the NCS (1970-72). This error has been
corrected in this handbook.
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Figure 5.1 Mean body weight for infants aged 6 to 11 months, sexes combined, by survey year. Blue bars represent data from U.S. National Health And Nutrition Examination
Surveys (NHANES); Canadian data (NCS, 1970-72), in red, added for comparison. Data
restricted to infants ≥6 months to match minimum age of 1976-80 NHANES Survey.
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Figure 5.2 Mean body weight for toddlers aged 1 to <4 years, sexes combined, by survey
year. Blue bars represent data from U.S. NHANES; Canadian data (NCS 1970-72), in red,
added for comparison.
5.2 Mean Body Weight is Increasing in the Canadian Population
Data and statistics presented on body weight in the 1997 Compendium were compiled from Canadian surveys conducted between 1970 and 1988. Average body weight for adults is increasing with time in Canada
(Orpana et al. 2007; see Figure 5.3). The trend to increasing mean body weight is also evident in children,
teens, and seniors (Figure 5.3). Between 1970-72 (NSC survey) and 2005 (CCHS Cycle 3.1), mean adult
body weight (sexes combined) increased by approximately 10 kg; between 1988 (CFLRI 1988; see also
Stephens and Craig 1990) and 2005 (CCHS Cycle 3.1), mean adult body weight (sexes combined) increased by almost 6 kg. Because the average body weights recommended for risk assessment in the 1997
Compendium were based on the 1988 CFLRI study, the body weight exposure factor for adults (as well as
for children, teens, and seniors) required review and updating.
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2013 Canadian Exposure Factors Handbook
Figure 5.3 Mean measured body weight by age group and year of survey, sexes combined.
Data for survey sample only. Data for adults and seniors in years 2004 and 2005 were
calculated to match age range of earlier data (adults = 20-59 years; seniors = 60+ years).
5.3 Self-Reported versus Measured Body Weight
Statistics Canada usually collects data on self-reported body weight; survey participants are asked to report
their own weight, rather than having it measured in a clinic or by a trained technician using standard methods and equipment. Individuals tend to under-report their body weight (Sherry et al. 2007; Shields et al.
2008). Both self-reported and measured body weight were collected for a sub-sample of survey participants
for Statistics Canada surveys in 2004 (CCHS Cycle 2.2) and 2005 (CCHS Cycle 3.1). For teens, adults, and
seniors, the average differences between self-reported weight and measured weight were as follows:
Teens:
■■ 2004: -1.04 kg (range: -7.58 to +14.32 kg)
■■ 2005: -2.29 kg (range: -72.00 to +59.60 kg)
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Adults:
■■ 2004: -1.98 kg (range: -20.15 to +18.00 kg)
■■ 2005: -2.44 kg (range: -74.70 to +65.00 kg)
Seniors:
■■ 2004: -2.30 kg (range: -36.00 to +10.05 kg)
■■ 2005: -2.49 kg (range: -64.60 to +45.25 kg)
The difference between self-reported and measured body weight is depicted in Figure 5.4
Due to the unreliability of self-reported body weight, this handbook includes body weight exposure factors
based on measured body weight.
Figure 5.4 Measured versus self-reported body weight. Data from CCHS Cycle 2.2 (2004)
and CCHS Cycle 3.1 (2005), genders combined. Only survey participants with both measured and self-reported weights included.
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5.4 Infant and Toddler Body Weight
Recent data on body weight of infants <1 year of age is not publically available in Canada. The last Canadian survey that reported measured body weights for this age group was the 1970-72 NCS (reviewed by
Richardson 1997).
Given that, unlike older age groups, the infant age group is not experiencing increasing average weight with
time (Figure 5.1), the Canadian data from the 1970-72 NCS is still an accurate reflection of current average
body weight for infants. Therefore, these NCS data were used to establish mean body weight for the infant
age group given herein.
Likewise for toddlers, average body weight has not increased over time (Figure 5.2). However, unlike for
infants, more recent Statistics Canada data from 2004 (CCHS cycle 2.2) were available on body weight for
toddlers. These 2004 data were used herein to revise the average body weight for the toddler age group.
5.5 Conclusions
Considering the trends in body weight over time and the lower reliability of self-reported data, mean body
weights for toddlers, children, teens, adults, and seniors recommended herein are based on data from the
2004 CCHS survey (Cycle 2.2), in which body weight was measured for all age groups except infants. Data
from CCHS Cycle 3.1 (2005) were omitted because the youngest age group considered in that survey was
teens (i.e., ≥12 years of age).
Because infant body weight has not changed appreciably in the last 3 to 4 decades, and because the only
available Canadian data on body weight for infants was collected by the NCS (1970-72), the mean infant
body weight recommended herein is based on the NCS data.
Table 5.2 presents updated recommendations for body weight assumptions for risk assessment. When applying probabilistic risk assessment methods, the means and standard deviations of body weight presented
in Table 5.2 can be used to define log-normal probability density functions of body weight.
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Table 5.2 Recommended body weight (kg), by age group (years) and gender a, b
Gender
Infant
(0 to <1)
Toddler
(1 to <4)
Child
(4 to <12)
Teen
(12 to <20)
Adult
(20 to <65)
Senior
( ≥65)
Female
Male
---
14.8 ± 2.2
15.8 ± 2.4
34.7 ± 14.1
35.7 ± 15.6
61.0 ± 13.2
69.3 ± 15.7
69.8 ± 16.3
83.3 ± 15.3
67.6 ± 13.7
80.6 ± 14.2
Combined
8.1 ± 2.0
15.3 ± 2.3
35.2 ± 14.9
65.2 ± 14.5
76.5 ± 15.8
73.6 ± 13.9
a Data expressed as arithmetic mean body weight with ± standard deviation.
b Modified from data in Table 5.1 using statistical weighting variables for the full Canadian population provided by Statistics Canada with Public
Use Microdata Files; they apply to the full Canadian population and are for use in risk assessment.
The mean and standard deviation for infant body weight reflect the revised age range of 0 to <12 months,
not 0 to 6 months as in the 1997 Compendium. Despite increasing the infant age range by several months,
the average body weight for infants is not significantly different than the weight determined in 1997. At that
time, the average weight was 8.2 ± 2.9 kg; now it is 8.1 ± 2.0 kg. Current average infant weight remains
similar to the previous value because of the correction of the adjustment error in the 1997 Compendium.
The mean body weight for toddlers recommended in this handbook is lower than that recommended in the
1997 Compendium due to 2 factors:
■■ The age range for toddler is shorter now (1 to <4 years) than it was in 1997
(7 months to <5 years);
■■ This handbook corrects the false assumption in the 1997 Compendium that
toddlers’ mean body weight increases with time; in fact, there has been no
increase in their mean body weight.
Recommended mean body weights for child, teen, adult, and senior have all increased relative to 1997.
Body weight increases for these age groups range from 2% to 11%, depending on age and gender.
5.6 References
Canadian Fitness and Lifestyle Research Institute (CFLRI). 1988. Unpublished data provided to GM Richardson. CFLRI, Ottawa. Cited in Richardson, 1997.
Orpana H, MS Tremblay and P Fines. 2007. Trends in weight change among Canadian adults. Statistics
Canada, Health Reports, 18 (2): 9-16.
Portier K, JK Tolson and SM Roberts. 2007. Body weight distributions for risk assessment. Risk Analysis,
27(1): 11-26.
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2013 Canadian Exposure Factors Handbook
Richardson, GM. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment. O’Connor Associates Environmental Inc., Ottawa, ON.
Sherry B, ME Jefferds and LM Grummer-Strawn. 2007. Accuracy of Adolescent Self-report of Height and
Weight in Assessing Overweight Status: A Literature Review. Arch Pediatr Adolesc Med, 161(12):11541161
Shields M, S Connor Gorber and MS Tremblay. 2008. Estimates of obesity based on self-report versus direct measures. Statistics Canada, Health Reports, 19 (2): 1-16.
Stephens, T. and CL Craig. 1990. The Well-Being of Canadians: Highlights of the 1988 Campbell’s Survey.
Canadian Fitness and Lifestyle Research Institute, Ottawa. 95p. + appendices + data.
2013 Canadian Exposure Factors Handbook
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6.0 INHALATION RATES
Inhalation rates are required for assessment of risk to human health due to inhalation of airborne substances. Current methods in risk assessment assume that the amount of exposure, and hence the risk, is directly
proportional to the volume of contaminated air inspired (U.S. EPA 1989; Health Canada 2012).
6.1 General Population
In Canada, to assess risk of non-occupational exposures to airborne contaminants, the most commonly used
assumption to describe breathing rate is the volume of air inhaled over 24 hours (see Richardson 1997; HC
2010a, 2012; CCME 2006). However, no empirical data exist on total volume of air inhaled over 24 hours.
Ventilation rates are usually measured as minute volumes in litres per minute (L/min). Minute volumes vary
among individuals and with level of physical activity. As a result, the amount of air breathed over a 24-hour
period can be estimated by multiplying the subject’s minute volume at each activity level by the number
of minutes spent at the respective activity levels over the course of a day (with total duration of activities
adding to 1440 min/day).
The 1997 Compendium recommended 24-hour inhalation rates based on work conducted for Health Canada
that was ultimately published as Allan and Richardson (1998). That work reported the results of a Monte
Carlo analysis to generate probability density functions of 24-hour inhalation rates; that analysis combined
time-activity information with ventilation rates reported or appropriate for the various age groups and activity levels considered.
Allan et al. (2008) recently updated their 1998 analysis, incorporating new data on ventilation rates and
time-activity patterns for all age groups. As observed in 1998, gender appeared to affect both minute volumes and activity patterns of people older than 6 months. As a result, estimated 24-hour breathing rates for
males were on average 8% to 27% higher than for females of the same age group. Because of the introduction of new data, particularly on time-activity patterns, mean inhalation rate per age group changed slightly
from 1998 to 2008, with toddlers being most impacted. For toddlers, derived mean inhalation rate declined
by approximately 10% compared to the 1998 analysis.
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2013 Canadian Exposure Factors Handbook
Because the age groups defined herein (see Table 3.1) are different than those used by Allan et al. (2008),
mean inhalation rates recommended in this handbook are different than the rates recommended in Allan
et al. Using data from Brochu et al. (2006a,b) and data summarized by the U.S. EPA (2011), percentage
change in mean inhalation rates between the old and new age ranges were calculated as follows:
■■ Mean inhalation rate herein for infants (0 to <1 year) is 21% greater than the
rate in Allan et al. for infants (0 to 6 months);
■■ Mean inhalation rate herein for toddlers (1 to <4 years) is 5% less than the
rate in Allan et al. for toddlers (7 months to <5 years); and
■■ Mean inhalation rate herein for children (4 to <12 years) is 2% less than the
rate in Allan et al. for children (5 to <12 years).
Age ranges for teens, adults, and seniors are unchanged or changed insignificantly; therefore, the estimates
presented by Allan et al. (2008) are retained herein for these older age groups.
Table 6.1 presents recommended 24-hour breathing rates by age group and gender for the Canadian population. When applying probabilistic risk assessment methods, the means and standard deviations of inhalation
rate presented in Table 6.1 can be used to define log-normal probability density functions of inhalation rate
for the various age groups.
Table 6.1 Recommended inhalation rate (m3/day), by age (years) and gender a, b
Gender
Female
Male
Combined
Infant c
(0 to <1)
--2.7 ± 0.6
Toddler d
(1 to <4)
7.4 ± 2.0
8.5 ± 2.3
7.9 ± 2.2
Child e
(4 to <12)
13.6 ± 3.1
14.9 ± 3.4
14.2 ± 3.4
Teen f
(12 to <20)
14.0 ± 3.2
17.1 ± 4.1
15.6 ± 4.0
Adult f
(20 to <65)
15.3 ± 3.5
18.0 ± 4.2
16.6 ± 4.1
Senior f
( ≥65)
13.9 ± 3.3
16.1 ± 4.2
15.0 ± 3.9
a Data expressed as arithmetic mean inhalation with ± standard deviation.
b Modified from Allan et al. (2008) for age ranges defined herein for infants, toddlers, and children. All probability density functions are log-normally
distributed.
c Mean for infants is 21% greater than reported by Allan et al. (2008) due to the increase in the upper age limit for this age group; the standard
deviation was not changed.
d Means for toddlers are 5% lower than reported by Allan et al. (2008) due to the alteration of the upper and lower age limit for this age group; the
standard deviations were not changed.
e Means for children are 2% lower than reported by Allan et al. (2008) due to the decrease of the lower age limit for this age group; the standard
deviations were not changed.
f Means for teens, adults, and seniors are unchanged from Allan et al. (2008).
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6.2 Construction and Utility Workers
Workers involved in excavation, construction, installation of underground services, or remediation activities associated with the maintenance, remediation, or redevelopment of a contaminated site may be exposed
to higher levels of risk due to more intimate contact with contaminated environmental media. However,
such individuals will be exposed for a relatively short duration. For example, Health Canada (2004) originally prescribed the duration of on-site exposure for construction and utility workers as only 2 weeks per
year, although an assumed 3 months of exposure is now becoming more common. Considering inhalation
exposures to such workers at contaminated and brownfield sites is now standard for contaminated site risk
assessments in Canada, for both federal (see HC 2004, 2010, 2012) and provincial jurisdictions. Applying
data on ventilation rates and activity levels, Allan et al. (2009) used methods analogous to those of Allan et
al. (2008) to determine hourly inhalation rates for outdoor workers at these sites. Allan et al. (2009) reported
the following hourly inhalation rates:
■■ Males: 1.40 ± 0.51 m3/h; and
■■ Females: 1.25 ± 0.66 m3/h.
This handbook recommends the above hourly inhalation rates when quantifying inhalation exposures for
outdoor workers at contaminated sites and brownfields. Any other exposure factors required to assess exposure and risk for these workers should be the same as those defined for the adult age group elsewhere in
this handbook.
When applying probabilistic risk assessment methods, the means and standard deviations of inhalation rate
presented above can be used to define a log-normal probability density function of inhalation rate for construction and utility workers.
6.3 References
Allan, M. and Richardson, GM 1998. Probability Density Functions Describing 24-hour Inhalation Rates
for Use in Human Health Risk Assessments. Human and Ecological Risk Assessment, Vol. 4(2), 379-408.
Allan M, GM Richardson and H Jones-Otazo. 2008. Probability density functions describing 24-hour inhalation rates for use in human health risk assessments: an update and comparison. Human and Ecological
Risk Assessment, 14: 372-391.
Allan M, H Jones-Otazo, A Li-Muller and GM Richardson. 2009. Inhalation rates for risk assessments involving construction workers in Canada. Human and Ecological Risk Assessment, 15(2): 371-387.
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2013 Canadian Exposure Factors Handbook
Brochu P, J Ducré-Robitaille and J Brodeur. 2006a. Physiological daily inhalation rates for free-living individuals aged 1 month to 96 years, using data from doubly labeled water measurements: A proposal for air
quality criteria, standard calculations and health risk assessment. Human and Ecological Risk Assessment
12:675-701.
Brochu P, J Ducré-Robitaille and J Brodeur. 2006b. Physiological daily inhalation rates for free-living
pregnant and lactating adolescents and women aged 11 to 55 years, using data from doubly labeled water
measurements for use in health risk assessment. Human and Ecological Risk Assessment 12:702-735.
CCME (Canadian Council of Ministers of Environment). 2006. A Protocol for the Derivation of Environmental and Human Health Soil Quality Guidelines. PN 1332, CCME, Winnipeg, MB, Canada. Online at:
http://www.ccme.ca/assets/pdf/sg_protocol_1332_e.pdf
HC (Health Canada). 2004. Federal Contaminated Site Risk Assessment in Canada Part I: Guidance on
Human Health Preliminary Quantitative Risk Assessment (PQRA). Contaminated Sites Program, Health
Canada, Ottawa, ON.
HC (Health Canada). 2010. Federal Contaminated Site Risk Assessment in Canada Part V: Guidance on
Human Health Detailed Quantitative Risk Assessment for Chemicals (DQRAChem). Contaminated Sites
Program, Health Canada, Ottawa, ON. Available by contacting Health Canada at: cs-sc@hc-sc.gc.ca
HC (Health Canada). 2012. Federal Contaminated Site Risk Assessment in Canada Part I: Guidance on Human Health Preliminary Quantitative Risk Assessment (PQRA), version 2.0. Contaminated Sites Program,
Health Canada, Ottawa, ON. Online at: http://www.hc-sc.gc.ca/ewh-semt/pubs/contamsite/part-partie_i/
index-eng.php
Richardson, GM. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment. O’Connor Associates Environmental Inc., Ottawa, ON.
U.S. EPA (US Environmental Protection Agency). 1989. Risk Assessment Guidance for Superfund, Volume
I: Human Health Evaluation Manual (Part A). Interim Final. EPA/540/1-89/002. Office of Emergency and
Remedial Response, Washington, DC, USA
U.S. EPA (US Environmental Protection Agency). 2011. Exposure Factors Handbook 2011 Edition (Final).
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/052F.
2013 Canadian Exposure Factors Handbook
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7.0 SKIN SURFACE AREA
There is no available Canadian data on the direct measurement of skin surface area. The U.S. EPA (1985;
1997; 2011) concluded that skin surface area could be accurately estimated from data on height (cm) and
body weight (kg). Table 7.1 lists the equations established by the U.S. EPA (1997) to estimate total skin
surface area and the area of various body parts (arms, hands, legs, and feet).
Table 7.1 Equations established by U.S. EPA (1995) to estimate body surface area (m2)
from data on height (cm) and weight (kg)
Body part
Equation a
Total surface
Arms (upper + lower)
Surface area = 0.0239 × H0.417 × W0.517
Surface area = 0.00223 × H0.748 × W0.201 (females)
Surface area = 0.00111 × H0.561 × W0.616 (males)
Hands
Surface area
Surface area
Surface area
Surface area
Legs (upper + lower)
Feet
= 0.0131 × H0.0274 × W0.412 (females)
= 0.0257 × H-0.218 × W0.573 (males)
= 0.00240 × H0.626 × W0.542 (females + males)
= 0.000618 × H0.725 × W0.372 (females + males)
a In equations, H = height, in cm; W = weight, in kg.
The U.S. EPA (2011) found very little variation in predicted body surface area (or parts thereof), regardless
of which predictive equation or other approach the prediction was based on. Therefore, body surface area
for toddler, child, teen, adult, and senior were determined using the same methods used in the 1997 Compendium. However, measured (not self-reported) height and weight data were used and were obtained from
CCHS Cycle 2.2 (2004). To determine body surface area for infants, data from the Nutrition Canada Survey
(1970-72) were used for 2 reasons: to be consistent with the weight data used for this age group (see Section
5.4), and because mean infant height has not changed with time (see Figure 7.1).
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Figure 7.1 Mean infant height by year of U.S. NHANES survey. Canadian data (Nutrition
Canada Survey, 1970-72) added for comparison. *Minimum age surveyed was 2 months;
for all other surveys the minimum age surveyed was 0 months.
Although Canadians tend to under-estimate their weight (see Section 5.3), they also tend to over-estimate
their height (Elgar and Stewart 2008; Shields et al. 2008), as shown in Figure 7.2. Therefore, body surface
area estimates provided herein were determined from measured, not self-reported, height and weight values.
The U.S. EPA equations listed in Table 7.1 were used to estimate total skin surface area and skin surface
area of specific body parts (i.e., arms, hands, legs, and feet) for each age group and gender (Table 7.2).
2013 Canadian Exposure Factors Handbook
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Figure 7.2 Measured versus self-reported height. Data from CCHS Cycle 2.2 (2004) and
CCHS Cycle 3.1 (2005), genders combined. Only survey participants with both measured
and self-reported heights included.
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Table 7.2 Skin surface area (m2) for total body and various parts, by age group and
gender a,b
Age group
and gender
Total body
surface
Arms c
Hands
Legs d
Feet
Infant e
Female
Male
Combined
--
--
--
--
--
0.4064 ± 0.0675
0.0596 ± 0.0181
0.0342 ± 0.0040
0.1039 ± 0.0198
0.0284 ± 0.0045
Toddler
Female
Male
Combined
0.6412 ± 0.0648
0.6700 ± 0.0685
0.6557 ± 0.0682
0.1150 ± 0.0085
0.0791 ± 0.0099
0.0970 ± 0.0202
0.0450 ± 0.0029
0.0462 ± 0.0037
0.0456 ± 0.0034
0.1784 ± 0.0207
0.1875 ± 0.0221
0.1830 ± 0.0219
0.0455 ± 0.0044
0.0474 ± 0.0046
0.0465 ± 0.0046
Child
Female
Male
Combined
1.1911 ± 0.3127
1.2064 ± 0.3241
1.1989 ± 0.3186
0.1817 ± 0.0324
0.1645 ± 0.0540
0.1730 ± 0.0455
0.0652 ± 0.0113
0.0687 ± 0.0147
0.0669 ± 0.0132
0.3685 ± 0.1096
0.3741 ± 0.1142
0.3713 ± 0.1120
0.0834 ± 0.0202
0.0844 ± 0.0209
0.0839 ± 0.0206
Teen
Female
Male
Combined
1.6753 ± 0.1904
1.8495 ± 0.2350
1.7594 ± 0.2302
0.2301 ± 0.0136
0.2756 ± 0.0424
0.2521 ± 0.0385
0.0818 ± 0.0069
0.0953 ± 0.0119
0.0883 ± 0.0118
0.5412 ± 0.0668
0.6077 ± 0.0843
0.5733 ± 0.0827
0.1146 ± 0.0104
0.1264 ± 0.0131
0.1203 ± 0.0132
Adult
Female
Male
Combined
1.7784 ± 0.2163
2.0182 ± 0.2061
1.8990 ± 0.2103
0.2343 ± 0.0149
0.3057 ± 0.0377
0.2701 ± 0.0284
0.0861 ± 0.0080
0.1046 ± 0.0106
0.0953 ± 0.0094
0.5752 ± 0.0752
0.6664 ± 0.0743
0.6210 ± 0.0744
0.1191 ± 0.0113
0.1349 ± 0.0114
0.1271 ± 0.0113
1.7399 ± 0.1893
1.9769 ± 0.1927
0.2287 ± 0.0134
0.2979 ± 0.0350
0.0852 ± 0.0069
0.1035 ± 0.0100
0.5593 ± 0.0661
0.6499 ± 0.0692
0.1160 ± 0.0102
0.1319 ± 0.0107
1.8262 ± 0.2220
0.2539 ± 0.0408
0.0919 ± 0.0120
0.5922 ± 0.0801
0.1218 ± 0.0129
Senior
Female
Male
Combined
a Data expressed as arithmetic mean surface area with ± standard deviation.
b Values derived from measured height and weight data and the equations listed in Table 7.1.
c Includes upper and lower arms.
d Includes upper and lower legs.
e No gender differentiation for infants.
The U.S. EPA (2011) recommends the body surface area assumptions given for children and teens in Boniol
et al. (2008). As shown in Table 7.3, estimated surface areas of body parts, as a percent of total body surface
area, stated herein are reasonably similar to the data in Boniol et al. Differences are minor, ranging from
0.24% to 3.18%. Therefore, the body surface area values presented in Table 7.2 are considered acceptably
accurate for assessment of risks posed by dermal exposure to environmental contaminants.
2013 Canadian Exposure Factors Handbook
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When using probabilistic risk assessment methods to evaluate dermal exposure to chemicals, the means and
standard deviations of body surface areas presented in Table 7.2 can be used to define log-normal probability density functions of skin surface area.
Table 7.3 Surface area for various body parts as a percentage of total body surface area
and compared to Boliol et al. (2008)
Age Group
& Gender
Child
Male
Child
Female
Teen
Male
Teen
Female
Body Part
Hands
Feet
Legs c
Arms d
Hands
Feet
Legs c
Arms d
Hands
Feet
Legs c
Arms d
Hands
Feet
Legs c
Arms d
Total Body Surface Area (%)
Boniol et al. b
This
Handbook a
5.78
7.04
30.71
13.42
5.61
7.04
30.64
15.61
5.16
6.85
32.81
14.85
4.90
6.86
32.27
13.82
4.75
6.80
27.53
14.25
4.75
6.53
28.55
13.70
4.70
6.60
29.73
14.93
4.33
6.08
30.15
13.98
Difference (%)
1.03
0.24
3.18
0.83
0.86
0.51
2.09
1.91
0.46
0.25
3.08
0.08
0.57
0.78
2.12
0.16
a In this column, estimates derived from full data, not simply converted from means presented in Table 7.2.
b In this column, as presented by Boniol et al. (2008), estimates for child derived as the mean of ages 4, 6, 8, and 10 years; for teen, estimates
derived as the mean of ages 12, 14, 16, and 18 years.
c Includes upper and lower legs.
d Includes upper and lower arms.
7.1 References
Boniol M, JP Verriest, R Pedeux and JF Dore. 2008. Proportion of skin surface area of children and young
adults from 2 to 18 years old. Journal of Investigative Dermatology, 128: 461–464.
Elgar FJ and JM Stewart. 2008. Validity of Self-report Screening for Overweight and Obesity: Evidence
from the Canadian Community Health Survey. Can J Pub Health, 99(5): 423-427
34
2013 Canadian Exposure Factors Handbook
Shields M, S Connor Gorber and MS Tremblay. 2008. Estimates of obesity based on self-report versus direct measures. Statistics Canada, Health Reports, 19(2): 1-16.
U.S. Environmental Protection Agency (U.S. EPA). 1985. Development of statistical distributions or ranges
of standard factors used in exposure assessments. EPA/600/8-85-010, Washington, D.C.
U.S. EPA. Exposure Factors Handbook (1997 Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/P-95/002F a-c, 1997.
U.S. EPA (US Environmental Protection Agency). 2011. Exposure Factors Handbook 2011 Edition (Final).
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/052F.
2013 Canadian Exposure Factors Handbook
35
8.0 TIME-ACTIVITY
Exposure to volatile organic compounds occurs mainly indoors, while exposure to components of smog
and other industrial air pollutants occurs mainly outdoors. Therefore, risk assessments must distinguish
between time spent indoors and time spent outdoors. Canadians typically spend 20 or more hours per day
indoors (Statistics Canada 1991; Health Canada 1994, 2004; Richardson 1997), but differentiation of that
indoor time between home and work, school, shopping, or other indoor environments has not been defined.
Due to a lack of Canadian data for younger age groups, statistics and information on time-activity patterns
presented in the 1997 Compendium were only for teens ≥15 years of age, adults, and seniors. For the infant,
toddler, and child age groups, Health Canada (2012) recommends that time spent outdoors be set equivalent
to that of adults, based on the assumption that these younger age groups will be accompanied by a parent
or guardian during outdoor activity. Due to a continuing lack of Canadian data on the time-activity patterns
for younger age groups, this same assumption will continue. An alternative is to consult data available from
the U.S. EPA (2008, 2011); however, directly applying U.S. data to the Canadian situation may not be appropriate due to climatic and other differences between the locations.
The statistics on time-activity presented in the 1997 Compendium were based on data from Statistics Canada’s 1992 General Social Survey (GSS), Cycle 7. However, since that time, the increased use of the Internet
and computer-based gaming has altered the time spent by Canadians inside the home versus out-of-doors.
For example, time spent by teens at sedentary indoor activities increased between 2000 and 2010, with increases in time reported spent with computers, video games, and TV-viewing exceeding time spent reading
(Figure 8.1). It should be noted that time spent reading included reading of online (Internet) materials.
The most recent Statistics Canada data available on time-activity patterns were collected in 2010 as part
of the GSS, Cycle 24. Similar to Cycle 7 (1992), data were collected only for teens 15 to <20 years of age,
adults, and seniors. The sample was evenly distributed over a 12-month period to account for seasonal
variability. The sample was also evenly divided between the 7 days of the week. Sampling was stratified to
represent all provinces, but excluded residents of the Yukon, Northwest Territories, and Inuvik. Full-time
residents of institutions were also excluded. GSS Cycle 24 involved a total sample size of 15,390 Canadians
aged 15 years and older. The survey data for teens (15 to <20 years of age) were considered applicable to
the teen age group as a whole (12 to <20 years).
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2013 Canadian Exposure Factors Handbook
Figure 8.1 Average reported time spent at indoor sedentary activities, by year of CCH Survey. Data for teens, sexes combined.
Note that these data relate to a 24-hour (1440-minute) period and do not represent any individual’s timeactivity pattern over an extended period of time. For example, if a proportion of the population reported
spending 1440 minutes indoors for the date surveyed, one cannot assume that they would do so for 7 days
a week, 52 weeks a year, for 80 years (or any other combination of days, weeks, or years).
8.1 Time Spent Indoors versus Outdoors
Table 8.1 presents the time Canadian teens, adults, and seniors spend indoors and outdoors (and time spent
doing particular indoor/outdoor activities, as described in the following sections). Females spend slightly
more time indoors and slightly less time outdoors than do males. On average, teens spend only 10 to 12 minutes per day outdoors while at home and less than 60 minutes total for all outdoor environments, perhaps
reflecting the increased use of the Internet, etc. (see Figure 8.1). Total time spent outdoors by teens is down
from the approximately 80 minutes per day found in 1992 data (see Richardson 1997). Time spent outdoors
by adults and seniors is also reduced relative to 1992 data. The proportion of GSS participants reporting
100% of their time spent indoors (i.e., 0.0 minutes outdoors) is presented in Table 8.2.
2013 Canadian Exposure Factors Handbook
37
Table 8.1 Time-activity factors (minutes/day), by age group and gender a,b
At Home
Age Group and
Indoors
Outdoors
c
Awake
Gender
Away from Home
Indoors
d
Washing/
Dressing
Outdoors
e
Indoors or
Other Outdoor
Total
Total
in Vehicle
Activities f
Indoors
Outdoors
Teen
g
1396 ± 122
44 ± 122
1383 ± 124
57 ± 124
150 ± 133 (N=27)
1389 ± 123
51 ± 123
411 ± 305
117 ± 89 (N=106)
1387 ± 101
53 ± 101
Female (N = 364)
908 ± 328
11 ± 39
556 ± 140
52 ± 37
33 ±114
488 ± 314
Male (N = 397)
892 ± 297
12 ± 43
545 ± 140
32 ± 29
45 ± 108
491 ± 290
Combined (N = 761)
900 ± 312
12 ± 41
550 ± 140
42 ± 35
39 ± 111
489 ± 301
976 ± 303
29 ± 69
481 ± 236
42 ± 38
24 ± 65
N/Ah
Adult
Female (N = 6186)
Male (N = 4804)
901 ± 311
43 ± 95
416 ± 235
31 ± 34
28 ± 84
469 ± 322
156 ± 140 (N=117)
1369 ± 132
71 ± 132
Combined (N = 10990)
943 ± 309
35 ± 82
453 ± 238
37 ± 37
26 ± 74
436 ± 316
137 ± 120 (N=223) 1379 ± 116
61 ± 116
1177 ± 265
34 ± 76
654 ± 210
43 ± 43
19 ± 68
209 ± 249
N/Ah
1386 ± 112
54 ± 112
1342 ± 143
98 ± 143
101 ± 91 (N=67)
1368 ± 128
72 ± 128
Senior
Female (N = 2139)
Male (N = 1500)
1107 ± 277
69 ± 119
601 ± 229
28 ± 33
29 ± 76
235 ± 258
Combined (N = 3639)
1148 ± 272
49 ± 98
633 ± 220
37 ± 40
23 ± 72
219 ± 253
a Data expressed as arithmetic mean with ± standard deviation.
b Source: Statistics Canada’s General Social Survey, Cycle 24 (2010).
c Particularly relevant for the assessment of risks posed by residential contaminated sites.
d Calculated as [Time At Home Indoors – Total Time Asleep]; particularly relevant for assessment of risks posed by time-dependent indoor exposures, such as to indoor dust (see Wilson et al., in press), requiring activities other than sleep.
e Particularly relevant for assessment of risks posed by exposure to contaminated tap water via showering or bathing.
f Included as a conservative estimate of time spent in environments that may result in exposure to contaminated sediments, for use in the derivation of sediment quality guidelines for protection of human health; only 2.06% of 15,390 survey participants reported time >0.0 minutes.
g No Canadian data on time-activity patterns for persons aged <15 years are available.
h Sample size too small to differentiate sexes.
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2013 Canadian Exposure Factors Handbook
Table 8.2 Percent of surveyed population reporting spending all (100%) of their day indoors or none (0%) of their day outdoors, by age and gender a
Age Group
& Gender b
Teen h
Female (364)
Male (397)
Combined (761)
Adult
Female (6186)
Male (4804)
Combined (10990)
Senior
Female (2139)
Male (1500)
Combined (3639)
All Day at Home
Indoors c,d
No Time at
Home Outdoors e
All Day Anywhere Indoors f
No Time Anywhere
Outdoors g
8.2
5.3
6.4
83.0
84.1
83.6
55.2
50.6
52.8
55.2
50.6
52.8
6.6
5.2
6.0
66.2
66.2
66.2
50.8
50.9
50.8
50.8
50.9
50.8
18.0
9.8
14.6
65.3
50.9
59.4
52.6
41.7
48.1
52.6
41.7
48.1
a Source: Statistics Canada’s General Social Survey, Cycle 24 (2010).
b Numbers in parentheses = survey sample size
c All day = 1440 minutes = 24 hours.
d Includes only at respondent’s home; excludes all other indoor locations.
e Includes only the respondent’s property; excludes all other outdoor locations.
f Includes all indoor locations, including the respondent’s home.
g Includes all outdoor locations, including on the respondent’s property.
h Surveyed teens were 15 to 19 years of age, but data assumed to be applicable to all teens 12 to <20 years of age.
8.2 Time Spent Washing and Bathing
When water supplies are contaminated, people are potentially at risk of inhaling volatile contaminants and
aerosols or absorbing water-borne chemicals through their skin. As a result, assessments of risk posed by
water-borne contaminants should include the time spent per day exposed to water when washing, bathing,
and/or showering.
Canadian data relating solely to time showering or bathing do not exist. However, the GSS Cycle 24 (2010)
reports the total duration of time spent “washing/dressing.” Including time spent dressing means that these
data slightly overestimate the actual time spent in contact with tap water. However, these data provide a
reasonable and objective estimate of time spent washing and bathing, which is superior to using an estimate
based solely on professional judgment. These data are included in Table 8.1.
8.3 Time Spent Indoors at Home Awake
Concern is increasing for the exposure that can arise from contaminants contained in indoor dust (Whitehead et al. 2011). For example, ingestion and/or inhalation of indoor dust, particularly by children, has been
2013 Canadian Exposure Factors Handbook
39
linked to elevated levels of lead in blood (Dixon et al. 2009). To further explore this potential risk, Health
Canada launched the Canadian House Dust Study in 2007 (Rasmussen et al. 2011; see also www.hc-sc.
gc.ca/ewh-semt/contaminants/dust-poussiere-eng.php) to quantify the concentrations of lead and numerous
other inorganic and organic contaminants in household settled dust on floors and other surfaces.
Exposure to indoor dust is dependent on the time spent at activities that place people in direct contact with
surfaces upon which dust has settled. Those activities will occur only when a person is awake, active, and
inside the home. Therefore, to facilitate risk assessments of contaminants in household settled dust, this
handbook includes the average time spent by teens, adults, and seniors inside the home and awake.
8.4 Time Spent at “Other Outdoor Activities”
Health Canada and various provincial jurisdictions are now developing sediment quality guidelines for the
protection of human health (see Health Canada 2010, for example). Analogous to soil quality guidelines,
sediment quality guidelines will define concentrations of contaminants in freshwater and/or marine sediments that do not pose a risk to human health. To derive these guidelines, data are required on the time spent
in environments and circumstances when sediment exposure might occur (e.g., time at the beach). No data
have been published by Statistics Canada or other agency on time spent specifically where sediment contact
might occur. However, Statistics Canada collects data from participants in the GSS series on time spent
at “other outdoor activities,” which is a broad category for time spent at anything not otherwise captured
during Statistics Canada GSS surveys. Time spent “at the beach” is an example given for this category (Statistics Canada 2011). Time spent at “other outdoor activities” will be a conservative over-estimate of time
spent at locations where sediment contact might occur.
Table 8.1 includes data on time at “other outdoor activities” for teens, adults, and seniors. Data for Canadians younger than 15 years of age is not available. Overall, for those who reported spending time at “other
outdoor activities,” the average time spent amounted to slightly more than 2 hours per day (Figure 8.2),
which exceeds the average for total time outdoors reported in the same table. Only 317 of the surveyed
15,390 Canadians (2.06%) reported spending any time at “other outdoor activities”; this small sample size
results in skewed and unrepresentative (of the entire population) statistics. However, these data were included in this handbook as a conservative upper bound estimate of time spent “at the beach” or other unspecific
outdoor locations. Average time spent at “other outdoor activities” appears to vary little from one province
to another (Figure 8.2).
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2013 Canadian Exposure Factors Handbook
Figure 8.2 Time (min/day) spent at “other outdoor activities,” for all ages (≥15 years) and
sexes combined. Regional mean values presented for information only; sample sizes too
small for valid regional differentiation.
8.4 References
HC (Health Canada). 1994. Human Health Risk Assessment for Priority Substances. Priority Substances
List assessment report. Health Canada, Ottawa, ON. Cat. No. En40-215/41E
Dixon SL, JM Gaitens, DE Jacobs, W Strauss, J Nagaraja, T Pivetz, JW Wilson, and PJ Ashley. 2011. Exposure of U.S. children to residential dust lead, 1999-2004: II. The contribution of lead-contaminated dust
to children’s blood lead levels. Environ Health Perspect, 117 (3): 468–474.
Health Canada. 2010. Workshop on Approaches for Human Health-Based Sediment Quality Guidelines and
Sediment Risk Assessment. Contaminated Sites Division, Health Canada. Vancouver, BC, June 2-3, 2010.
HC (Health Canada). 2012. Federal Contaminated Site Risk Assessment in Canada Part I: Guidance on Human Health Preliminary Quantitative Risk Assessment (PQRA), version 2.0. Contaminated Sites Program,
Health Canada, Ottawa, ON. Online at: http://www.hc-sc.gc.ca/ewh-semt/pubs/contamsite/part-partie_i/
index-eng.php
2013 Canadian Exposure Factors Handbook
41
Rasmussen PE, S Beauchemin, M Chenier, C Levesque, LCW MacLean, L Marro, H Jones-Otazo, S Petrovic, LT McDonald and HD Gardner. 2011. Canadian House Dust Study: Lead Bioaccessibility and Speciation. Environ Sci Technol, 45: 4959–4965.
Richardson, GM. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment. O’Connor Associates Environmental Inc., Ottawa, ON.
Statistics Canada. 1991. Where does time go? Catalogue no. 11-612-MPE, no. 4, Housing, Family and Statistics Division, Statistics Canada, Ottawa.
Statistics Canada. 2011. Cycle 24: Time-Stress and Well-Being Public Use. Microdata File Documentation
and User’s Guide. Catalogue no. 12M0024X, Social and Aboriginal Statistics Division, Statistics Canada,
Ottawa, ON. Dated December 2011.
U.S. EPA (U.S. Environmental Protection Agency). 2008. Child-Specific Exposure Factors Handbook (Final Report) 2008. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/096F.
U.S. EPA (U.S. Environmental Protection Agency). 2011. Exposure Factors Handbook 2011 Edition (Final). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/052F.
Whitehead T, C Metayer, P Buffler, SM Rappaport. 2011. Estimating exposures to indoor contaminants
using residential dust. J Expo Sci Environ Epidemiol, 21(6): 549-564.
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2013 Canadian Exposure Factors Handbook
9.0 SOIL INGESTION RATES
9.1 Overview
Although Statistics Canada and other Canadian agencies do not provide data on soil ingestion rates, a section
on this subject is warranted here. Human health risk assessment for contaminated sites is driven in large part
by the assumed soil ingestion rate. Ingestion of soil is a potential source of human exposure, particularly to
non-volatile contaminants (metals, PAHs, PCDD/DF, PCBs, etc.). In fact, ingestion of soil is the greatest
exposure pathway for these contaminants, more than dermal exposure, consumption of produce, inhalation
of aerially entrained soil particles, and other direct and indirect exposure pathways. Yet soil ingestion is the
least understood and least quantified of human exposure factors. Limitations and uncertainties associated
with the current database of soil ingestion studies are discussed in detail by U.S. EPA (2011, 2008) and are
summarized by Ozkaynak et al. (2011).
Risk assessment guidance in Canada, as prescribed by Health Canada (2012) and various provincial environmental agencies (see OMOE 2011a,b, for example), is inconsistent in calculating dose from soil ingestion versus dose from other pathways (inhalation, dermal exposure, food ingestion, water ingestion, etc.).
For other pathways, risk assessment guidance prescribes use of human exposure factors defined as the
average, typical, or central tendency value (such as for body weight, inhalation rate, body surface area, food
intake rate, water intake rate, etc.). These average or typical exposure factor values are combined with the
maximum measured on-site contaminant concentration in soil (or other upper-bound representation of concentration) to establish an exposure dose that will be a “reasonable worst case,” ensuring that potential risks
are not underestimated. However, Canadian environmental agencies have broadly adopted upper-bound
values (greater than the mean or typical value) for soil ingestion rate. When these maximal soil intake rates
are combined with the maximum soil concentration, the resulting exposure dose significantly exceeds a reasonable worst-case dose (such as, say, the 99th percentile dose for the hypothetical population). To be more
comparable to other exposure pathways, the soil ingestion pathway requires use of an average, typical, or
central tendency soil ingestion rate.
2013 Canadian Exposure Factors Handbook
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The maximum soil contaminant concentration is generally prescribed to ensure a reasonably equitable and
comparable assessment of risk (and subsequent equitable application of risk management measures) across
all contaminated sites. Environmental site investigators collect and analyze different numbers of soil samples from various sites. They do not attempt to conduct a statistically representative sampling of the site
from which an accurate assessment of risk would be feasible. Instead, they focus on known or suspected
contaminant “hot spots” in order to confirm the presence or absence of contamination, delineate contaminant plumes and deposits, and identify zones that require remediation. Although this sampling strategy
cannot accurately determine average contaminant concentration across the site, it will identify the likely
maximum or near maximum on-site contaminant concentration (Health Canada 2012). To ensure that the
risk assessment for one site is equitable and comparable to risk assessments for other sites, use of the maximum measured soil concentration is prescribed for dose and risk calculations (Health Canada 2012; OMOE
2011b). Although this approach is equitable across all sites, soil ingestion exposures are over-estimated
compared to exposures via other pathways that are quantified by average or typical exposure factors (e.g.,
inhalation, dermal exposure, etc.). The result is the likely excessive remediation of soil-borne contamination, with associated excess expenditures for remediation by the Canadian federal government, through the
Federal Contaminated Site Action Plan, by industries, and by other agencies and organizations responsible
for contaminated site cleanup.
Table 9.1 presents current Canadian assumptions for soil ingestion rate used in risk assessment.
Table 9.1 Soil ingestion rate assumptions (mg/day) used by various Canadian environmental regulatory agencies
Age group
Health Canada
(2012) a
Ontario
(OMOE 2011a)
Quebec
(INSPQ 2012)
Infant
20
30
20
Toddler
80
200
85
Child
Adult
Senior
20
20
20
50
50
50
35
20
20
a Same values generally employed by the CCME (2006) and in BC (BCE 1996), Alberta (AE 2010), and the Atlantic provinces (ARBCA 2007);
Manitoba has adopted CCME soil quality guidelines and, by assumption, the same soil ingestion rates as CCME (see www.gov.mb.ca/conservation/envprograms/contams/standards/index.html)
Wilson Scientific/Meridian Environmental (2006; prepared on behalf of Health Canada) and Van Holderbeke et al. (2007; see also Bierkens and Cornelis 2007) have published non-critical reviews—meaning
they did not critique or analyze study design issues—of soil ingestion studies. Both reviews considered soil
tracer and mechanistic (hand-to-mouth) study designs. They concluded that average or typical soil ingestion
rate in toddlers is not >100 mg/day and is likely approximately 40 mg/day as a median or typical value. For
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2013 Canadian Exposure Factors Handbook
adults, soil ingestion rate probably ranges between 10 and 40 mg/day as a mean or typical value.
Since the publication of the above reviews, a number of new studies have been published. As previously
mentioned, the U.S. EPA (2011, 2008) detailed the limitations and uncertainties in existing studies. To address some of the deficiencies noted by the U.S. EPA, Stanek et al. (2012) re-analysed and refined their previous mass-balance tracer studies on soil ingestion in children; they determined that the mean soil ingestion
rate in children aged 1 to 7 years is 26 mg/d, with a 95th percentile ingestion rate of 79 mg/d.
Doyle et al. (2010) provided a critical review of studies that used mass-balance tracer methods to quantify
soil ingestion rate. Consistent with the U.S. EPA (2011, 2008), Doyle et al. found that several issues may
invalidate the ingestion rate estimates from individual studies, including but not limited to the following:
■■ Transit time misalignment (i.e., uncertainty about when soil may be ingested
and when it may appear in the feces);
■■ Failure to characterize tracer levels in the soils actually ingested, which are
generally assumed to be the subjects’ yard soil;
■■ Variable gastrointestinal absorption of tracers originally thought to have little
or no absorption; and
■■ Unanticipated tracer content of foods and medicines.
Of particular interest was their conclusion that estimates of soil ingestion based on tracer methods reflect
the minimum detectable soil ingestion rate that would be discernible based on study sample size. In other
words, soil ingestion estimates based on tracer method studies are influenced as much (or more) by statistical limitations and low statistical power as they are by actual soil ingestion. Doyle et al. (2010) suggested
that a sample size of 225 soil ingestion measurements would reliably detect a soil ingestion rate of 20 mg/d
(Health Canada’s assumed soil ingestion rate for adults); this corroborates findings by Calabrese et al.
(1989), who estimated a required sample size/study effort of 90 person-weeks to reliably detect a soil ingestion rate of 100 mg/d. No tracer studies to date have achieved these levels of study participation or duration.
Following their 2010 review, Doyle et al. (2012) investigated soil ingestion in 7 adult subjects of a remote
First Nations community in British Columbia during an extended (3 week) camping and fishing excursion.
The study intentionally focused on subjects in a rural/remote population engaged in activities considered
highly likely to result in greater soil ingestion than reported for urban/suburban dwellers (the focus of previously published investigations). Using mass-balance tracer methods, Doyle et al. (2012) determined the
mean soil ingestion rate was 75 ± 120 mg/d (90th percentile = 211 mg/d). Although considerably greater
than soil ingestion rates reported for urban/suburban adults, the mean soil ingestion rate was still lower than
current Canadian assumptions used to characterize soil ingestion rate for adults involved in activities likely
to cause high soil ingestion (e.g., construction work).
2013 Canadian Exposure Factors Handbook
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Perhaps due to the increasing uncertainties about the validity of fecal tracer study results, combined with the
expense and complexity of these studies, there has been a resurgence of interest in a mechanistic approach
to quantifying soil ingestion rates. Mechanistic methods were first published in the mid-1970s (see Lepow
et al. 1974, 1975; Day et al. 1975; Duggan and Williams 1977). Although mechanistic studies do not attempt to directly measure soil ingestion, they readily and accurately quantify the variables associated with
the actions, factors, and behaviours that lead to soil ingestion (e.g., soil loading of the surfaces or objects
touched, subsequent soil loading to the hands touching those surfaces, hand-to-mouth and object-to-mouth
frequency, and surface area of hands or objects being mouthed). As a result, the mechanistic approach
provides more statistical certainty (i.e., less uncertainty) in soil ingestion estimates than do tracer studies;
estimates are also more certain because, unlike with some tracer studies, negative soil ingestion rates are not
possible with a mechanistic approach (Doyle et al. 2010).
Using analogous (though technically different) methods and probabilistic techniques, Ozkaynak et al. (2011)
and Wilson et al. (2013) used mechanistic approaches to estimate outdoor soil and indoor dust ingestion
rates. Whereas Ozkaynak et al. (2011) focused on children aged 3 to 6 years, Wilson et al. (2013) focused
on the traditional age groups considered in Canadian risk assessments—infants, toddlers, children, teens,
and adults. Despite the technically different methods used, these authors independently reached remarkably
similar results, as shown in Table 9.2. These estimates are also similar to the mean soil ingestion rate of
26 mg/d determined by Stanek et al. (2012) in their re-analysis and refinement of mass-balance tracer studies.
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2013 Canadian Exposure Factors Handbook
Table 9.2 Comparison of dust and soil ingestion rate estimates (mg/day) based on mechanistic studies derived by Wilson et al. (2013) and Ozkaynak et al. (2011) a; results from
Stenek et al. (2012), from reanalysis of tracer studies, added for comparison
Indoor Dust Ingestion Rate
Age Group
Wilson et
al. (2013) b
Ozkaynak et
al. (2011) c
Outdoor Soil Ingestion Rate
Wilson et
al. (2013)
Ozkaynak et
al. (2011) c
Stanek et
al. (2012) d
Infant
(0 to 6 mo)
36 ± 130
--
N/A e
--
--
Toddler
(7 mo to <5 years)
41 ± 71
19.80 ± 36.54
20 ± 26
40.96 ± 78.29
25.5 ± 15.5
Child
(5 to <12 years)
32 ± 59
--
23 ± 32
--
--
Teen
(12 to <20 years)
2.2 ± 3.6
--
1.5 ± 2.6
--
--
Adult
(20 to <60 years)
2.6 ± 4.2
--
1.6 ± 2.9
--
--
Senior
(≥60 years)
2.6 ± 4.2
--
1.2 ± 2.7
-
--
a Data expressed as arithmetic mean with ± standard deviation.
b Values for indoor dust ingestion assume equal proportion (50:50) of hard (e.g., hardwood, linoleum) and soft (carpet) floor coverings per household.
c Analysis for 3- to 6-year-olds only; approximately equal to toddlers as defined by Wilson et al. (2013) and Health Canada (2012).
d Meta-analysis considered for 1- to 7-year-olds; most comparable to toddlers as defined by Health Canada (2012).
e Infants assumed not to be placed in direct contact with outdoor soil.
9.2 Conclusions
The soil ingestion rates currently used by Health Canada (2012) originate from the earliest North American
mass-balance tracer studies (see Health Canada 1988, 1994), the validity and reliability of which have been
critiqued by the U.S. EPA (2011, 2008) and others. Recent refinement of these data (Stanek et al. 2012)
demonstrates that the mean ingestion rate for children is approximately one-third the intake rate originally
interpreted by Health Canada. Recent mechanistic assessments (Ozkaynak et al. 2011; Wilson et al. 2013)
further support a mean ingestion rate for toddlers of 20 to 40 mg/day, rather than 80 mg/day as prescribed
by Health Canada (2012). In fact, 80 mg/day is likely greater than the 95th percentile soil ingestion rate for
this age group (Stanek et al. 2012; Wilson et al. 2013).
2013 Canadian Exposure Factors Handbook
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Prescribing average or typical values for most exposure factors (e.g., body weight, body surface area, inhalation rate, food and water ingestion rates) yet prescribing soil ingestion rates that equal or exceed the 95th
percentile values, results in errors in risk assessments. These errors are leading to unnecessary and excessive remediation; remediation above and beyond what is necessary to achieve acceptable risk.
Therefore, to assess risk posed to human health by contaminated sites, it is recommended herein to use
the mean soil ingestion rates presented by Wilson et al. (2013; see Table 9.2). If probabilistic methods are
planned, the mean and standard deviations presented by Wilson et al. (2013) can be used to define a lognormal probability density function for this variable.
9.3 References
AE (Alberta Environment). 2010. Alberta Tier 1 Soil and Groundwater Remediation Guidelines. Alberta
Environment. Dated December 2010. Online at: http://environment.gov.ab.ca/info/library/7751.pdf
ARBCA (Atlantic Risk-Based Corrective Action). 2007. ATLANTIC RBCA (Risk-Based Corrective
Action) Version 2.0 for Petroleum Impacted Sites in Atlantic Canada; User Guidance. Updated March 2007.
Online at: http://www.atlanticrbca.com/eng/ref_doc_v2.html
BCE (BC Environment). 1996. Overview of CSST Procedures for the Derivation of Soil Quality Matrix
Standards for Contaminated Sites. Risk Assessment Unit, Environmental Protection Department, BC Environment. Dated January 31, 1996. Online at: http://www.env.gov.bc.ca/epd/remediation/standards_criteria/
standards/overview_of_csst.htm
Bierkens J and C Cornelis. 2007. Estimates of Hourly Dust and Soil Ingestion Rates for Children and Adults In- and Outdoors. Epidemiology, 18(5): S34-S35.
DOI: 10.1097/01.ede.0000276523.03217.fc
Calabrese EJ, R Barnes, EJ Stanek, H Pastides, CE Gilbert, and P Veneman. 1989. How much soil do young
children ingest: An epidemiologic study. Regul Toxicol Pharmacol, 10: 123–137.
CCME (Canadian Council of Ministers of the Environment). 2006. Protocol for Development of Environmental and Human Health Soil Quality Guidelines. CCME, Winnipeg, MB CANADA. Available at http://
www.ccme.ca/assets/pdf/sg_protocol_1332_e.pdf
Day JP, M Hart, MS Robinson. 1975. Lead in urban street dust. Nature, 253:343–345.
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Doyle JR, JM Blais and PA White. 2010. Mass balance soil ingestion estimating methods and their application to inhabitants of rural and wilderness areas: A critical review. Science of the Total Environment, 408:
2181–2188
Doyle JR, JM Blais, RD Holmes and PA White. 2012. A soil ingestion pilot study of a population following
a traditional lifestyle typical of rural or wilderness areas. Science of the Total Environment, 424: 110–120
Duggan MJ and S Williams. 1977. Lead-in-dust in city streets. Sci Total Environ, 7:91–97.
Health Canada. 1988. DRAFT–Reference Values for Canadian Populations. Working Group on Reference
Values, Environmental Health Directorate, Health Canada, Ottawa, ON. Dated July 4, 1988.
Health Canada. 1994. Human Health Risk Assessment for Priority Substances. Priority Substances List
assessment report. Health Canada, Ottawa, ON. Cat. No. En40-215/41E
Health Canada. 2012. Federal Contaminated Site Risk Assessment in Canada Part I: Guidance on Human Health Preliminary Quantitative Risk Assessment (PQRA), version 2.0. Contaminated Sites Program,
Health Canada, Ottawa, ON. Online at: http://www.hc-sc.gc.ca/ewh-semt/pubs/contamsite/part-partie_i/
index-eng.php
INSPQ (Institut National de santé publique du Quebec). 2012. Lignes directrices pour la realization des
évaluations du risque toxicologique d’origine environnementale au Québec. Direction de la santé environnementale et de la toxicologie, INSPQ, Montreal, QC CANADA. Dated Février 2012
Lepow ML, L Bruckman, RA Rubino, S Markowitz, M Gillette and J Kapish. 1974. Role of airborne lead
in increased body burden of lead in Hartford children. Environ Health Perspect, 7: 99-102.
Lepow ML, L Bruckman, M Gillette, S Markowitz, R Robino and J Kapish. 1975. Investigations into sources of lead in the environment of urban children. Environ Res., 10(3): 415-426.
OMOE (Ontario Ministry of Environment). 2011a. Rationale for the Development of Soil and Ground
Water Standards for Use at Contaminated Sites in Ontario. PIBS 7386e01. Standards Development Branch,
Ontario Ministry of the Environment, Toronto, ON. Dated April 15, 2011.
OMOE (Ontario Ministry of Environment). 2011b. Modified Generic Risk Assessment (Tier 2) Spreadsheet
Model. Standards Development Branch, Ontario Ministry of the Environment, Toronto, ON.
Ozkaynak HK, J Xue, VG Zartarian, G Glen, and L Smith. 2011. Modeled Estimates of Soil and Dust Ingestion Rates for Children. Risk Analysis, 31(4): 592-608.
2013 Canadian Exposure Factors Handbook
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Stanek EJ III, EJ Calabrese and B Xu. 2012. Meta-Analysis of Mass-Balance Studies of Soil Ingestion in
Children. Risk Analysis, 32 (3): 433-447.
U.S. EPA (U.S. Environmental Protection Agency). 2008. Child-Specific Exposure Factors Handbook. Report EPA/600/R-06/096F, U.S. EPA, Washington, DC.
U.S. EPA (U.S. Environmental Protection Agency). 2011. Exposure Factors Handbook: 2011 Edition. Report EPA/600/R-090/052F, U.S. EPA, Washington, DC.
Van Holderbeke M, C Cornelis, J Bierkens and R Torfs. 2007. Review of the Soil Ingestion Pathway in
Human Exposure Assessment: Final Report. Study in support of the BeNeKempen project, subproject on
harmonization of the human health risk assessment methodology. Prepared for VITO (Flanders) and RIVM
(the Netherlands).
Wilson R, H Jones-Otazo, S Petrovic, I Mitchell, Y Bonvalot, D Williams, GM Richardson. 2013. Revisiting dust and soil ingestion rates based on hand-to-mouth transfer. Human and Ecological Risk Assessment,
19(1), in press. DOI: 10.1080/10807039.2012.685807.
Wilson Scientific/Meridian Environmental. 2006. Critical Review of Soil Ingestion Rates for Use in Contaminated Site Human Health Risk Assessments in Canada: Final Report. Prepared for the Contaminated
Sites Division, Safe Environments Program, Health Environments and Consumer Safety Branch, Health
Canada, Ottawa, ON Canada.
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10.0 NEW DATA — 1997 AGE GROUPS
The revised ranges for the various age groups defined in Section 3.0 may be problematic for some regulatory agencies that prefer to retain the original age ranges. Therefore, to ensure that the latest data are readily
available to all jurisdictions, Table 10.1 presents revised exposure factors derived from the latest Statistics
Canada and other data but retaining the original age groups as defined in the 1997 Compendium (Richardson 1997).
Table 10.1 Revised exposure factors for Infant, Toddler, and Child age groups, using age
ranges defined in the 1997 Compendium (Richardson 1997) a, b
Body Surface Areas (m2)
Age Group
Body
Inhalation
& Gender
Weight (kg)
Rate
(m3/day)c
Total Body
Legs
Arms
(upper &
(upper & lower)
Feet
Hands
lower)
Soil In-
Indoor Dust
gestion
Ingestion
Rate
Rate
(mg/
(mg/day) d,e
day) d
Infant
(0 to 6 mo)
Female
N/A f
N/A f
N/A f
N/A f
N/A f
N/A f
N/A f
N/A
Male
Combined
6.9 ± 1.6
2.18 ± 0.59
0.362 ± 0.054
0.055 ± 0.018
0.091 ± 0.016
0.025 ± 0.004
0.032 ± 0.004
14.8 ± 3.1
7.76 ± 1.97
0.658 ± 0.065
0.118 ± 0.009
0.184 ± 0.021
0.047 ± 0.004
0.046 ± 0.003
Male
15.6 ± 3.2
8.85 ± 2.25
0.686 ± 0.069
0.082 ± 0.010
0.193 ± 0.022
0.049 ± 0.005
0.047 ± 0.004
Combined
Toddler
(7 mo to <5 y)
Female
N/A f
g
36 ± 130
N/A f
N/A f
15.2 ± 3.2
8.31 ± 2.19
0.672 ± 0.068
0.099 ± 0.020
0.189 ± 0.022
0.048 ± 0.005
0.046 ± 0.003
20 ± 26
41 ± 71
Child
(5 to <12 y)
Female
38.9 ± 15.3
13.85 ± 3.14
1.232 ± 0.313
0.187 ± 0.032
0.383 ± 0.110
0.086 ± 0.020
0.067 ± 0.011
N/A f
N/A f
Male
39.7 ± 16.1
15.21 ± 3.44
1.248 ± 0.324
0.171 ± 0.054
0.389 ± 0.114
0.087 ± 0.021
0.070 ± 0.015
Combined
39.3 ± 15.7
14.52 ± 3.38
1.240 ± 0.319
0.179 ± 0.046
0.386 ± 0.112
0.087 ± 0.021
0.068 ± 0.013
23 ± 32
32 ± 59
a Data expressed as arithmetic mean with ± standard deviation.
b Exposure factors for Teen, Adult, and Senior assumed to differ insignificantly from those presented in this handbook.
c After Allan et al. 2008.
d After Wilson et al. 2013.
e Values presented for 50:50 hard:soft indoor surfaces (hardwood versus carpeted floors, for example); see Wilson et al. (2013) for intakes based
solely on different floor covering types.
f Not available; insufficient data exist to differentiate by gender.
g Not available; infants assumed not to be placed in direct contact with soils.
2013 Canadian Exposure Factors Handbook
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10.1 References
Allan M, GM Richardson and H Jones-Otazo. 2008. Probability density functions describing 24-hour inhalation rates for use in human health risk assessments: An update and comparison. Human and Ecological
Risk Assessment, 14: 372-391.
Richardson, GM. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment. O’Connor Associates Environmental Inc., Ottawa, ON.
Wilson R, H Jones-Otazo, S Petrovic, I Mitchell, Y Bonvalot, D Williams, GM Richardson. 2013. Revisiting dust and soil ingestion rates based on hand-to-mouth transfer. Human and Ecological Risk Assessment,
19(1), in press. DOI: 10.1080/10807039.2012.685807.
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2013 Canadian Exposure Factors Handbook