McGill University
Department of Civil Engineering
Lead levels in drinking water
Master’s Research
Project
G19-17
By
Mehdi Badel
May 2019
Montreal, Quebec
1
Acknowledgment
I would like to thank Professor Susan Gaskin for her support and supervision, Minsoo Cho for
being a great, helpful and organized team mate, and Douglas M. Dewan for helping me editing the
manuscript.
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Table of Contents
Abstract ____________________________________________________________________ 3
1 Introduction _______________________________________________________________ 4
2 Literature review ___________________________________________________________ 7
2-1 Lead __________________________________________________________________________ 7
2-2 Health risks ____________________________________________________________________ 8
2-2-1 Lead toxicity _______________________________________________________________________ 9
2-2-2 Acute toxicity _____________________________________________________________________ 10
2-2-2-1 Zamfara incident _______________________________________________________________ 11
2-2-3 Chronic toxicity ___________________________________________________________________ 11
2-2-3-1 Effects on nervous system _______________________________________________________ 11
2-2-3-2 Renal effects __________________________________________________________________ 12
2-2-3-3 Effects on cardiovascular system __________________________________________________ 13
2-2-3-4 Cancer _______________________________________________________________________ 14
2-2-4 Developmental and reproductive toxicity ________________________________________________ 15
2-2-4-1- Reproductive health effects ______________________________________________________ 15
2-2-4-2- Neurodevelopmental effects _____________________________________________________ 15
2-3 Water journey: Saint Lawrence River to home faucet ___________________________________ 16
2-3-1 Source of lead in drinking water _______________________________________________________ 18
2-4 Canadian Drinking Water Regulations ______________________________________________ 20
2-5 Flint water crisis ________________________________________________________________ 22
3 Methodology ______________________________________________________________ 25
3-1 Field survey ___________________________________________________________________ 25
3-2 Sampling procedure _____________________________________________________________ 26
3-3 Analyzing lead _________________________________________________________________ 28
3-3-1 ICP-MS principles of measurement ____________________________________________________ 28
4 Results and discussion ______________________________________________________ 29
5 Conclusion _______________________________________________________________ 34
6 References ________________________________________________________________ 40
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Abstract
For the majority of Montreal’s residents, the source of drinking water is the St. Lawrence River.
Prior to reaching the tap of the consumer, drinking water undergoes five distinct treatment
processes. After leaving the treatment plant, the water is distributed through pipes of the municipal
distribution network, which can be made of concrete, cast iron, steel, and/or plastic. Lastly, within
residential, institutional, or industrial buildings the interior plumbing system can be of lead, copper
and more recently plastics such as PVC or PEX. In Canada, prior to 1975, lead was an acceptable
material for drinking water pipes, and it was used in pipe solder until 1986. Many household and
institutional drinking water plumbing systems may still have lead components in place today,
which over time can potentially leach into the water as a result of corrosion. Nowadays the major
risk of human exposure to lead is through municipal drinking water and lead toxicity has
irreversible human health impacts. Lead primarily impacts the neurological system as well as the
renal, cardiovascular, and reproductive systems, with children being particularly vulnerable.
Recently the Government of Canada introduced new regulations to reduce the maximum
acceptable lead concentration in drinking water. As drinking water is the major source of lead
intake, the objective of this report is to measure lead exposure by testing water samples in an
institutional building in Montreal, Quebec. Stagnated and flushed water samples were collected
from drinking water taps from McDonald Engineering Building located in downtown McGill
University campus in order to test the lead levels. All but one sample met the proposed
governmental guideline for maximum acceptable concentration for lead, which is 5 ppb. These
samples were a subset of a prior study for copper testing and no statistically significant correlation
was found between copper and lead levels.
Keywords: drinking water, corrosion, lead toxicity
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1 Introduction
Water is life: the human body is composed of more than 60% water, so fresh water is necessary
for survival. Among the water resources on earth, only 3% is fresh water, of which two thirds is
frozen in icebergs. Potable water accessibility is one of the main concerns and challenges in many
regions of the world.
It is assumed that in Canada there is an infinite supply of fresh water, although some is fossil water
in lakes, glaciers, and underground aquifers. The majority of Canada’s fresh water flows northward
into the Arctic Ocean and Hudson’s Bay, thus it is not available for the population who lives in
the southern part of the country. The remaining water available, in the south, is overused and often
under stress.
Drinking water comes from surface or groundwater, and before it reaches the tap for consumption,
it should be treated to assure that is safe to drink. Canadian drinking water supplies are of excellent
quality. However, source water can become contaminated by materials it comes into contact with,
such as minerals, silt, vegetation, fertilizers, and agricultural run-off. While these impurities can
be harmless, some may pose a health risk.
The guidelines for Canadian drinking water quality address microbiological, chemical and
radiological contaminants. Aesthetic properties of water are also important for the quality of
drinking water for example the taste, odour, and turbidity.
Water can also be contaminated after leaving the water treatment plant. The distribution system
plays an important role in keeping the water clean. The municipality must ensure that the drinking
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water arrives safely to the consumer with acceptable concentrations of any contaminant, that is
meeting the Canadian standards and regulations for drinking water.
One of the main concerns regarding water distribution contamination is the plumbing materials
inside the building. Lead was once commonly used in drinking water systems because it is easy to
shape and resistant to corrosion. Although the National Plumbing Code of Canada allowed lead as
an acceptable material in pipes until 1975 and in solder until 1986, many drinking water systems
in Canada may still have some of these lead components in place today (Government of Canada,
2016). Lead can be leached from the interior surface of the pipes and enter the water, particularly
when the water chemistry is acidic.
Everyone is exposed to trace amounts of lead through air, soil, household dust, food, drinking
water and various consumer products. Since 1990, in Canada, lead additives have been removed
from gasoline and paints leaving the major source of lead exposure to be through drinking water.
Thus a method of controlling lead exposure to the population is through drinking water regulations
providing maximum allowable concentrations.
Lead poisoning is one of the major public health risks especially in developing countries. There
have been several occupational and public health measures performed to control lead exposure,
but cases of lead poisoning are still reported. Exposure to lead produces deleterious effects mainly
on central nervous system, but also on the renal and reproductive systems (Flora, Gupta, & Tiwari,
2012).
Fountains or faucets and plumbing parts can contribute to elevated lead levels at outlets in nonresidential buildings. Identifying and replacing the problematic components with non-leaded ones
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can be the most effective mitigation strategy in schools and buildings as well as in residences
(Government of Canada, 2017).
The rest of the report is organized as follows. The characteristics and uses of lead are summarized.
The deleterious health effects on human health due to both the acute and choric toxicity of lead is
presented in detail. This reviews the effects that have been studied on different parts of the human
body including the neural system, the kidneys, the cardiovascular and reproductive systems. Two
significant poisoning incidents due to lead toxicity have been reviewed. The first was a series of
lead poisonings in Zamfara State, Nigeria, causing at least 163 deaths within four months in 2010.
The second, known as the Flint water crisis, happened in 2014 when the drinking water source for
the city of Flint, Michigan was changed from Lake Huron to the more acidic Detroit River to
reduce costs. Due to insufficient water treatment, the acidic water lead leached from lead pipes in
the water distribution system into the drinking water, exposing over 100,000 residents to elevated
lead levels.
In the case of Montreal, the water source is the Saint Lawrence River, which after being treated is
distributed to the buildings and then reaches the point of use through the buildings plumbing
systems. The Canadian drinking water regulations are briefly presented, noting in particular the
maximum acceptable concentration (MAC) of the main elements and heavy metals having health
risks and concerns as specified by a number of different health organizations from around the
world. The methodology is presented, describing first the field study. 10 samples were selected
from a previous study on copper concentrations of 237 samples from 6 buildings on McGill
University campus, for which the lead concentration was examined. The results are presented and
discussed and finally the conclusions summarized.
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2 Literature review
In the first part of this section, the basic characteristics of lead are presented, followed by a
description of the different health risks due to lead exposure. The exposure can cause either acute
and/or chronic toxicity affecting the nervous system, kidneys, cardiovascular, and reproductive
system. A case of acute lead toxicity in Zamfara is presented.
In the second section, the journey of the drinking water from the Saint Lawrence River to the faucet
is reviewed, including the source of lead of the drinking water. Additionally, the Canadian drinking
water regulations and the maximum acceptable concentration (MAC) for heavy metals, collected
from different world wide organizations, are reviewed. Lastly, the Flint drinking water incident
(potable water with high lead contamination), which was due to lack of proper monitoring after
switching the water source, is briefly described.
2-1 Lead
Lead is found in small amounts in rocks and minerals in earth’s crust. It was one of the earliest
elements discovered by humans because of its unique properties of softness, malleability, and
corrosion resistance. The most abundant mineral is galena which is a lead sulfide (PbS). Plumbum
is the Latin word for lead which refers to soft metals. In the past, lead was used for plumbing due
to its high corrosion resistance and the word plumber or plumbing originates from the Latin word
Plumb. This metal is heavy, bright silvery, very dense, malleable, and tastes sweet but has no
smell. Lead is used for a variety of other purposes such as batteries, cable sheathes , and some of
the major industries using lead are machinery manufacturing, and shipbuilding.
Lead, in the periodic table, is considered to be a heavy metal. The term "heavy metal" describes a
class of agents having certain chemical similarities such as a divalent positive ion. Heavy metals
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have relatively high density (more than 5 g/cm3) and atomic weights. One of their characteristic is
that they are highly toxic or damaging to the environment.
Metals like copper, cobalt, chromium, iron, zinc, manganese, magnesium, selenium, and
molybdenum, are dense and/or toxic, however are also required micronutrients for humans or other
organisms. The essential heavy metals may be required to support key enzymes, act as cofactors,
or act in oxidation-reduction reactions. While necessary for health and nutrition, over exposure to
these elements can cause cellular damage and disease. Excess metal ions can interact with DNA,
proteins, and cellular components, changing the cell cycle, leading to carcinogenesis, or causing
cell death (Helmenstine, 2019).
2-2 Health risks
As lead has been removed from gasoline and paints, the main lead exposure for humans is from
drinking water. Lead service lines and solder in plumbing are the potential sources from which
lead can be leached into the water, reach the tap, and consumed.
Many studies have documented the adverse health effects on the human body and experiments on
animals have shown this to happen at very low exposure levels. In many cases, lead toxicity can
be observed below 10 µg/dL (Government of Canada, 2017).
There is no level of lead that is necessary or beneficial for human body and no “safe” level of
exposure to lead has been found. A summary of the total intake and uptake of lead from four major
sources is presented in Table 1.
The average intake of lead by an individual varies due to several factors such as consumer
behaviour, configuration of the plumbing system, water usage patterns, contact time of the water
with the plumbing, seasonal effects and water chemistry. Blood lead levels in the range of 10 to
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15 micrograms per decilitre in fetuses, infants, and children have been found to correlate with
adverse neurobehavioral and cognitive changes. At levels of more than 40 micrograms per
decilitre, body's ability to produce red blood cells decreases. (Government of Canada, 2017).
Table 1. Total intake and uptake of lead (µg/d) (Government of Canada, 2009).
Child (two yrs old,
13.6 kg)
Intake
Uptake
Adult (70kg)
Intake
Uptake
Medium Concentration
(%)
(%)
(%)
(%)
Air
0.06 µg/m3
Water
4.8 µg/L
0.36
(1.2)
2.9
(9.8)
0.14
(1.1)
1.45
(11.6)
1.2
(1.9)
77.2
(11.3)
0.48
(7.1)
0.72
(10.7)
Food
Various
15
(50.9)
7.5
(60.2)
52.5
(82.4)
5.25
(78)
Dust,
Dirt
140 µg/g
11.2
3.36
2.8
0.28
(38)
29.5
(27.0)
12.5
(4.4)
63.7
(4.2)
6.7
Total
2-2-1 Lead toxicity
Toxicity is the degree to which a substance can harm humans or animals. Acute toxicity involves
destructive impacts in an organism through a single or short-term exposure. Chronic toxicity is the
ability of a substance to cause harmful effects over an extended period of time, usually upon
continuous exposure, sometimes lasting for the entire life of the exposed organism (MedicineNet,
2018).
There is certain to be health problems due to lead in exposed humans and experimented animals.
As lead consumption has declined considerably in recent years, more data is available now on low
exposure effects.
The toxicity of lead has been extensively documented in humans, based on blood lead levels
(BLLs). Effects that have been studied include reduced cognition, increased blood pressure and
renal dysfunction in adults, as well as adverse neurodevelopmental and behavioural effects in
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children. The strongest association observed to date is between increased BLLs in children and
reductions in intelligence quotient (IQ) scores. The threshold below which lead levels are no longer
associated with adverse neurodevelopmental effects cannot be identified (Government of Canada,
2009).
Prior the establishment of civilization in North America, lead concentrations in the human body
were typically one-hundredth to one-thousandth of post-industrial levels. The average blood lead
level of Canadians today is less than 1.3 μg/dl (Government of Canada, 2009).
In the early 1970s, BLL up to 40 μg/dL were considered safe. Today, in adults, levels of 30 μg/dL
are tolerated. BLLs ranging from as little as 20 to 29 μg/dL are associated with a 39% increase in
mortality from all causes, a 46% increase in mortality from cardiovascular diseases, and a 68%
increase in mortality due to cancer (Lustberg & Silbergeld, 2002).
2-2-2 Acute toxicity
Acute toxicity signs are mainly neurological and gastrointestinal effects such as dullness,
irritability, poor attention span, headache, dizziness, weakness and memory loss as well as
epigastric pain, constipation, vomiting, anorexia, paresthesia, anemia and convulsions
(Government of Canada, 2017).
Table 2. BLL in acute toxicity (Government of Canada, 2017).
Acute toxicity
Encephalopathy
Gastrointestinal and musculoskeletal symptoms
Blood Lead Level (μg/dL)
Children
Adults
80 - 100
100 - 120
25 - 40
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Hypertension and oliguria are also recorded as acute toxicities caused by lead exposure. In severe
cases, encephalopathy, coma and death can occur (Government of Canada, 2009).
2-2-2-1 Zamfara incident
An acute poisoning incident happened in Zamfara, Nigeria. A total of 163 children out of 355
cases from several remote villages died of lead poisoning. The deaths were caused by a Chinese
company mining gold ore that also had high concentrations of lead. The deaths were discovered
during the country's annual immunization program, when officials realized there were virtually no
children in several remote villages. Villagers said the children had died of malaria, but blood tests
from local people showed high concentrations of lead, pointing to death from lead encephalopathy.
It is likely locals became sick after lead, removed during gold ore mineral processing,
contaminated local water systems (Héroux, 2017).
2-2-3 Chronic toxicity
Long-term exposure to low levels of lead may have effects on neural and cardiovascular systems,
and are linked to kidney diseases, and cancer.
2-2-3-1 Effects on the nervous system
The most susceptible and chief system targeted by lead is the nervous system. The peripheral
neurological system in adults and the central neurological system in children are affected by lead
exposure. Studies have also examined lead toxicity on nervous systems due to different BLLs.
Health Canada collected the results studies (Table 3) including prospective studies that have
followed populations over many years, as well as bone lead studies that reflect lead storage over
time, effects of very low BLL (<10 μg/dL), and so on. Results show that there is evidence of
adverse neurological effects at BLLs below 10 μg/dL but in general the association of low BLLs
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with adverse neurological endpoints is equivocal, and there were a significant amount of data that
did not support lead-induced adverse neurological effects. Moreover, the analyses were based on
single BLL measurements at the time of examination.
2-2-3-2 Renal effects
There is consistent evidence of adverse renal effects occurring at low BLLs. Long term exposure
below 10 µg/dL can lead to renal dysfunction. Individuals with hypertension or diabetes, may be
specifically vulnerable to lead-induced adverse renal effects. The lowest BLL associated with an
effect was 2.5–3.8 µg/dL in a hypertensive population. The main dysfunction caused by lead
toxicity in renal system is nephropathy which can ultimately lead to kidney failure (Government
of Canada, 2009). Table 4 presents two of the studies regarding renal health effects.
Table 3. Several studies on the association of BLL and human neurological effects (Government of Canada, 2017).
Blood Lead Level
Studies and results
• Saccadic eye movements (Baloh, et al., 1979);
(Glickman, Valciukas, Lilis, & Weisman, 1984)
• Changes in sensory evoked potential (Araki, Murata, &
Aono, 1987); (Counter & Buchanan, 2002)
• Signs of decreased cognitive performance, including loss
of memory, delayed reaction time and problems with
verbal concept formation (Haenninen, Hernberg,
Mantere, Vesanto, & Jalkanen, 1978); (Arnvig,
40 to 80 μg/dL
Grandjean, & Beckmann, 1980); (Mantere, Hänninen, &
General Neurological
Hernberg, 1982); (Baker, Feldman, White, & Harley,
effects
1983); (Hogstedt, Hane, Agrell, & Bodin, 1983);
(Campara, et al., 1984); (Stollery, 1996); (Stollery,
Banks, Broadbent, & Lee, 1989); (Stollery, Broadbent,
D.E., Banks, & Lee, 1991)
• Altered psychological state, such as depressed mood and
fatigue (Baker, Feldman, White, & Harley, 1983);
(Maizlish, Parra, & Feo, 1995)
Peripheral nerve function, measured by the conduction
velocity of electrically stimulated nerves (Seppalainen,
as low as 30 μg/dL
Hernberg, Vesanto, & Kock, 1983); (Chia, Chia, Chia, Ong,
& Jeyaratnam, 1996)
Average BLL over
Alterations in auditory verbal learning; these included
Canadian lead smelter
the period of
effects on memory storage and retrieval, but not on
workers
employment (mean = immediate learning, attention or memory span (Bleecker, et
39.0 ± 12.32 μg/dL)
al., 2005)
BLLs exceeding
54 Finnish storage
Long-lasting adverse effects on central nervous system
approximately 50
battery workers
functions (Hänninen, et al., 1998)
μg/dL
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Tibial lead levels, as an
indicator of long-term
exposure to lead
10.5 to 57.0 μg/g
1031 individuals were
administered the
MMSE with
concomitant BLL
measurements
mean of 4.5 μg/dL.
762 elderly men
(average age = 88.4
years)
mean of 3.7 μg/dL
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Adverse neurological effects at levels ranging from (KhalilManesh, et al., 1993); (Shih, et al., 2006); (Weuve, et al.,
2009). Tibia lead levels were also shown to correlate with
decreased cognitive function and reduced volume of the
total brain, the frontal and total grey matter as well as the
parietal white matter in lead workers (Stewart, et al., 2006)
Low scores, typically 23 or less on a scale of 30, are
associated with reduced cognitive function and increased
risk for dementia (Wright, et al., 2003)
Bone lead, however, was not significantly associated with
poor outcomes in the MMSE* or with age-related
neurodegeneration, except for a significant age interaction
with patella lead in the 57.6 μg/g group.
No association between BLL and MMSE score was found
(Nordberg, Winblad, Fratiglioni, & Basun, 2000)
*The mini-mental status exam MMSE assesses various endpoints related to orientation in place and time, memory, attention, language and
reasoning.
2-2-3-3 Effects on cardiovascular system
Increased blood pressure and risk of hypertension, development of peripheral arterial disease as
well as increased risk of coronary- and cerebrovascular-related morbidity and mortality have been
suggested by recent studies to be due to chronic lead exposure. Health Canada gathered several
studies on the association between BLL and blood pressure. Although there are studies that did
not support a significant connection between these two, there is evidence to suggest that specific
subpopulations including African Americans, pregnant and menopausal women as well as
children, may be more sensitive to lead-induced adverse cardiovascular effects.
Table 4. Several studies on the association between BLL and renal effects (Government of Canada, 2017).
Markers of kidney
dysfunction
Blood Lead Level
Studies and results
Reduced glomerular
filtration rate*;
Creatinine clearance**
Median BLL of 2.2 µg/dL
Examined in 820 Swedish women (Åkesson, et
al., 2005)
Creatinine clearance
A population of 965 men and
1016 women with mean BLLs
of 11.4 µg/dL and 7.5 µg/dL,
respectively
A 10-fold increase in BLL was associated with
a reduction of 10–13 mL/minute in creatinine
clearance (Staessen, et al., 1992)
*Glomerular filtration rate (GFR) is a test of how well the kidneys are working.
** The kidneys' ability to handle creatinine is called the creatinine clearance rate, which helps to estimate the glomerular filtration rate (GFR)
Creatinine clearance. Creatinine is a waste product from the normal breakdown of muscle tissue.
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Table 5. Several studies on the association between BLL and cardiovascular effects (Government of Canada, 2017).
Blood Lead Level
Studies and results
blood lead and tibia lead
measured in 575 workers
A mean baseline BLL of 31.4
μg/dL and followed over 3
years
Every 10 μg/dL increase in BLL was associated
with an annual increase in systolic blood
pressure of 0.9 mmHg (0.12 kPa), although no
association was found with tibia lead (Glenn, et
al., 2006)
70 occupationally
exposed policemen
followed over 5 years
BLLs exceeding 30 μg/dL
a significant association with systolic blood
pressure (Weiss, Munoz, Stein, Sparrow, &
Speizer, 1986)
systolic and diastolic
blood pressure as well as
hypertension in 339 men
and 345 women (Median
5.2 years follow-up)
mean BLL = 8.7 μg/dL
10548 Caucasian and
4404 African American
individuals
BLLs of ≥ 5 μg/dL
13946 adults in the U.S.
monitored over up to 12
years
BLLs of 3.6 μg/dL
It was determined that BLL had no consistent
effect on blood pressure and also did not
increase risk of hypertension at the levels
studied (< 30 μg/dL) (Staessen, Roels, &
Fagard, 1996)
an increased OR of 1.39 was measured in
African American females.
No effects on blood pressure were attributed to
blood lead in Caucasians.
BLLs of ≥ 5 μg/dL were significantly
associated with higher systolic and diastolic
blood pressure in African American men and
women.
Significant effects on systolic blood pressure in
African Americans,
No effects on Caucasians (Den Hond, Nawrot,
& Staessen, 2002) ; (Scinicariello, Abadin, &
Edward Murray, 2011)
After multivariable adjustment for age, sex,
body mass index, smoking, alcohol
consumption, socioeconomic status and
additional indicators of overall health, hazard
ratios were 1.25 and 1.55 for all-cause and
cardiovascular mortality, respectively (Menke,
Muntner, Batuman, Silbergeld, & Guallar,
2006)
2-2-3-4 Cancer
Epidemiological studies examining the relationship between long-term lead exposure and cancer
and mortality have reported positive and negative results. Epidemiological studies show that lead
is likely to have carcinogenicity when in high dose long term exposure. A few studies show the
strong association between cancer and lead exposure although some others indicate the effects of
other substances in co-exposure. Significant effects for lung, central nervous system, brain, kidney,
and stomach cancers have been found in studies that reported positive associations with BLL.
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2-2-4 Developmental and reproductive toxicity
2-2-4-1- Reproductive health effects
Lead has some adverse effects on the reproductive system in both men and women. In men some
of the major effects are including reduced libido, abnormal reduction in motility and number of
sperm, chromosomal damage, infertility, and abnormal prostatic function. Women are more
susceptible to infertility, miscarriage, premature membrane rupture, pregnancy hypertension and
premature delivery (Flora, Pachauri, & Saxena, 211). Delayed puberty in women seems to be the
most sensitive endpoint, with evidence of adverse effects with BLLs as low as 1.2 μg /dL
(Government of Canada, 2017).
2-2-4-2- Neurodevelopmental effects
Neurodevelopmental effects related to decreased intelligence, attention and performance that are
reported in infants and children exposed to lead early in life. The deleterious effects of lead in
developing children can potentially have lifelong health implications. BLLs as low as 0.8 µg/dL
have been associated with adverse neurodevelopmental effects in children. The effects are
particularly related to decreases in intelligence and may also include alterations in attention and
behaviour (Government of Canada, 2009).
IQ decreases have been reliably linked to limitations in academic achievements and earning
potential, and can serve as a surrogate for many other adverse neurological consequences beyond
the immediate effects of reduced performance on intelligence testing (Government of Canada,
2017).
It has been shown in epidemiological studies that BLL, tooth/dentin lead level and, in some cases,
umbilical cord BLL and maternal BLL are associated with adverse neurodevelopmental effects in
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infants and children, including inferior nerve impulses function, poorer academic achievement and
reading or math skills, abnormal behavior, decreased attention or executive functions, as well as
impairments of auditory and visual function. In many of these cases the BLL were reported below
10 µg/dL after controlling for confounding effects (Government of Canada, 2017).
Table 6. Several studies on the association between BLL and reproductive health effects (Government of Canada,
2017).
Blood Lead Level
Studies and results
•
Significant delays in breast and pubic hair
development as well as age at menarche
were observed in African American girls
Delayed breast and pubic hair development
in Mexican American girls
Caucasian girls were not significantly
affected (Selevan, et al., 2003)
600 Caucasian, 805
African American and
781 Mexican American
aged 8–18 years
a mean BLL of 3 µg/dL in
comparison with a BLL of 1
µg/dL
668 pregnant women
every increase in BLL of 5
µg/dL
OR for spontaneous abortion was 1.8 (BorjaAburto, et al., 1999)
489 boys at 8–9 years of
age
above 5 µg/dL
delayed markers of pubertal development based
on genitalia staging and testicular volume
(Hauser, et al., 2008); (Williams, et al., 2010)
•
•
2-3 Water journey: Saint Lawrence River to home faucet
In the 1600’s and 1700’s, Montrealers collected their water from communal wells, public
fountains, and directly from the streams and rivers that flowed through and around the island. It is
estimated that each person used about two bucketfuls (10-17L) per day, compared to the average
of 329 L used daily by each Canadian today (Redpath Museum, 2018).
In 1819, Montreal began to draw water directly from the St. Lawrence River, and this continues to
be the source of drinking water for many Montrealers. In 1856, the city developed three key parts
of its water processing complex: the canal de l’Aquaduc, the Atwater pumping station, and the
McTavish reservoir (Redpath Museum, 2018).
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Today for many Montrealers the source of drinking water is St. Lawrence River. The raw water is
drawn and then subjected to various treatments to make it drinkable for humans. To produce
drinking water from St. Lawrence River, it is put through five main treatment stages. The first
stage is screening, where the raw water passes through a grid to remove large debris including bits
of wood, trash, fish, etc. The next step is coagulation-flocculation-decantation or clarification. It
is common to add alum salt to the water to promote the agglomeration and forming of flakes which
eventually settle down at the bottom of the tanks. The third stage is a filtration process. In a large
basin, the water passes through a filter bed, one meter thick, usually composed of silica sand. This
type of filter removes about 85% of bacteria and retains the suspended solids in the water.
However, viruses, smaller than bacteria, manage to cross this barrier. A form of disinfection of
water is therefore necessary (Ville de Montréal, 2018). The next step is ozonation, in which odors
and tastes are eliminated from the water. Ozone is injected as bubbles at the base of the basin
within which the water circulates. In contact with this gas, organic matter oxidizes, bacteria are
destroyed and viruses become inactive. The last stage in producing drinking water is chlorination
to prevent the proliferation of bacteria in the distribution network (Ville de Montréal, 2018).
Montreal has an impressive network of water mains. With diameters ranging from 100 mm to over
2.74 m, made of different materials such as cast iron, steel, concrete and plastic. The main water
system consists of pipelines that carry water from treatment plants to secondary grids and
reservoirs. The secondary water supply network consists of local distribution networks fed by the
main network. It is from the secondary network that households as well as the industries,
businesses and institutions are supplied with drinking water (Ville de Montréal, 2018).
There are 6 water treatment plants in Montreal, Atwater and Charles J. Des Baillets are the two
main treatment plants with over 527 million cubic meter distribution volume annually (Table 7).
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Table 7. Montreal drinking water plants
average production (Ville de Montréal, 2018).
Average Production
Drinking water plants
(m 3 / day)
Atwater
650,000
Charles J.-Des Baillets
1,136,000
Pierrefonds
80,000
Lachine
65,000
Dorval
30,000
Pointe-Claire
60,000
Sainte-Anne-De-Bellevue
4,000
Lachine
3%
Dorval Pointe-Claire
3%
2%
Pierrefonds
4%
Sainte-AnneDe-Bellevue
0%
Atwater
32%
Charles J.-Des
Baillets
56%
Figure 1. Montreal average drinking water production
(Ville de Montréal, 2018).
The chemical and physical properties of water (Table 8) are important in terms of their impact on
human health. Physical properties such as temperature and pH influence other processes in water
treatment and they affect the rate of corrosion in the distribution system.
Table 8. Basic requirements for drinking water quality (Ersoz & Barrott, 2012).
Aesthetic requirements
✓ Turbidity
✓ Color
✓ Taste
✓ Odor
Human health related requirements
✓ Elimination of pathogens and toxic substances
✓ Limitation of problematic ions
✓ Limitation of radionuclides
Economical requirements
✓ Hardness
✓ Corrosion
✓ Iron and manganese
2-3-1 Source of lead in drinking water
The history of lead water pipes dates as far back as ancient Rome. The Romans used lead in their
water distribution systems as they regarded lead as the father of all metals and were completely
unaware of the negative health impacts. In 1983, a Canadian research scientist, Jerome
Nriagu, argued in a paper that the collapse of Roman civilization was likely hastened as a result
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of lead poisoning from different sources including vessels used for food and drink, however the
main source was lead pipes used in potable water supply. More recent research (Delile et al 2014)
although finding measurable quantities of lead in the sediments from the Tiber River and the
Trajanic Harbour (the maritime port of imperial Rome) that reflect the relative wealth of difference
times, have questioned whether this quantity would have been sufficient to result in sufficient
health impacts to have been the main cause of the Roman Empire’s fall.
Although Canadian municipalities started phasing out the use of lead in service lines to properties
in the 1960s, the National Plumbing Code permitted the use of lead until 1975 and lead solder until
1986. So today lead can be found in household plumbing materials such as pipes, fixtures, service
lines, and soldering. It may enter potable water through several points on its way from water
treatment plants to the point of consumption. The use of lead in valve parts or gaskets in treatment
plants, in older distribution mains, and service lines, all are potential sources. In dwellings, pipe
fittings, compounds, soldered joints and brass fixtures are also possible sources of lead (Figure 2).
Two types of building in Montreal might have lead in their water pipelines as per Ville de
Montreal:
1. Buildings that were built between 1940 and 1950 commonly known as wartime housing. The
water service connection running from these buildings to the city’s water supply system might be
made of lead. If that’s the case, it means that the standard has probably been met, but the risks of
non-compliance with the standard are higher (Ville de Montreal, 2017).
2. Buildings with fewer than eight units, built before 1970. The water service connection running
to the city’s water supply system from these buildings might be made of lead. However, even if it
is, this doesn’t mean that the standard hasn’t been met (Ville de Montreal, 2017).
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2-4 Canadian Drinking Water Regulations
As water can become contaminated by different pollutants and substances, the Federal
Government of Canada sets regulations to address the health risks due to (poor) water quality:
“To address this risk, Health Canada works with the provincial and territorial governments to
develop guidelines that set out the maximum acceptable concentrations (MAC) of these substances
in drinking water. These drinking water guidelines are designed to protect the health of the most
vulnerable members of society, such as children and the elderly. The guidelines set out the basic
parameters that every water system should strive to achieve in order to provide the cleanest, safest
and most reliable drinking water possible.” (Government of Canada, 2018)
Figure 2. Main sources of lead in drinking water (Health Canada, 2018).
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Among all the pollutants, heavy metals have severe health effects if they are found above
maximum acceptable concentration in drinking water. Most of the exposure to these metals is from
water consumption.
Heavy metals may enter the water system due to anthropogenic activities. There are maximum
acceptable concentrations, MAC determined by five different health organizations across the
world are shown in Table 9. The presence of heavy metals at any level below MAC is considered
safe.
Lead exists in the environment both naturally and as a result of human activities. Canadians are
exposed to small amounts of lead in water, food, air, soil and consumer products. Lead has
historically used in plumbing because of its special properties. Food and drinking water are the
primary sources of lead exposure for average adult populations.
Table 9. Heavy metals MAC from different health organizations (mg/l or ppm).
Element
Aluminium
Antimony
Arsenic
Barium
Boron
Cadmium
Chloride
Chromium
Copper
Fluoride
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Sodium
Uranium
Zinc
WHO
0.2
0.02
0.01
0.7
0.5
0.003
250
0.05
2
1.5
0.010
0.4
0.006
0.07
0.01
200
0.015
3
EU
0.2
0.005
0.01
1
0.005
250
0.05
2
1.5
0.2
0.010
0.05
0.001
0.02
0.01
200
-
EPA
0.05 to 0.2
0.006
0.01
2
0.005
0.1
1.3
4
0.015
0.002
0.05
0.030
-
CDPH
0.2
0.006
0.01
1
0.005
0.05
1.3
2
0.015
0.002
0.1
0.05
20 pCi/L
-
Health Canada
0.006
0.01
1
5
0.005
0.05
1
1.5
0.3
0.010
0.001
0.05
200
0.02
5
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Due to the harmful health effects caused by high lead concentrations in drinking water, which is
covered in this study, the MAC for lead in drinking water is currently 0.010 mg/L (ppm).
However, Health Canada recently proposed to reduce this amount to 0.005 mg/L (ppm):
“A maximum acceptable concentration (MAC) of 0.005 mg/L (5 µg/L or ppb) is proposed for total
lead in drinking water, based on a sample of water taken at the tap and using the appropriate
protocol for the type of building being sampled. Every effort should be made to maintain lead
levels in drinking water as low as reasonably achievable (or ALARA).” (Government of Canada,
2017)
Following Health Canada’s regulation, “in Quebec concentration of lead in drinking water may
not exceed 0.010 mg/L. Drinking water distribution system officials, including those of
municipalities, are responsible for ensuring that this standard is applied” (Gouvernement du
Québec, 2019).
2-5 Flint water crisis
The Flint water crisis is one of the infamous examples of lead leaching into drinking water. For
more than 45 years, the City of Flint purchased drinking water with optimized corrosion control
from the Detroit Water and Sewer Department (DWSD). In April 2014 as a cost saving measure,
the city switched drinking water lines to the Flint River temporarily without implementing
corrosion control, exposing 100,000 residents to the lead contaminated drinking water. Less than
one year later, collected water samples from city dwellings revealed drastically rising lead levels
in the drinking water corresponding to increasing water discoloration.
Several studies have shown that the destabilization of corrosion scales can cause lead and iron
problems if deposits begin to dissolve or detach into the water (Figure 4). Switching water to a
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different source changed the chemistry of water flowing down to the distribution network and the
water system will move toward a new equilibrium.
Before 2014, Flint was getting its water from the Detroit Water & Sewerage Department. Lake
Huron was the water source which was treated before sending it to Flint. Looking to lower the
city’s water costs, Flint officials decided in 2013 to take water from local authority, which was
building its own pipeline from the lake. Shortly after that, Detroit offered a short-term agreement
to Flint, which was declined by the city officials. As an interim solution, while waiting for the new
pipeline to be finished, Flint began taking water from the Flint River and treating it at the city’s
own plant.
Figure 4. Formation and destabilization of
protective scales: (a) corrosion inhibitors (e.g.,
PO43−) control the release of metals from
plumbing through the formation of protective
scales and (b) without corrosion inhibitors
previously formed protective scales can
become unstable and deteriorate resulting in
high lead and iron in water (Pieper, Tang, &
Edwards, 2017).
Figure 3. Foul-tasting, discolored water started coming out of
Flint’s taps in the summer of 2014 (Torrice, 2016).
In early 2015, the reports of high lead levels in drinking water started making news. A pediatrician
at Hurley Children’s Hospital, in Flint, released data showing that the number of Flint children
with elevated levels of lead in their blood had increased since the water change. The percentage of
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affected kids went from 2.4% to 4.9%. With evidence of lead contamination mounting, Flint
switched back to the Detroit water in October (Torrice, 2016).
What happened was that the iron, lead, and copper distribution pipes are corroded. This corrosion
occurs when oxidants, such as dissolved oxygen or chlorine disinfectant, react with elemental iron,
lead, or copper in the pipes. Flint, as an old city, relies on lead service lines. These lines connect
the mains water pipes to the homes’ water meters.
The inside surface of the pipes has a scale or passivation layer which protects the pipe’s metals
from corrosion and oxidation by the water. If the chemistry of the water is not optimized, then this
protecting layer may start to dissolve, or mineral particles may begin to flake off the pipe’s scale.
This exposes bare metal, allowing the iron, lead, or copper to oxidize and leach into the water
(Torrice, 2016).
As shown in Figure 4 with the presence of corrosion inhibitors, orthophosphates, the lead scales
develop on the surface of the pipes and this avoids the lead leaching into the water. That is the
reason why corrosion control plans includes orthophosphates in their corrosion compound to
encourage the formation of lead phosphates, which are largely insoluble and can add to the pipes’
passivation layer (Torrice, 2016).
Another important corrosion solution is controlling the water pH and alkalinity. With the absence
of phosphates and relatively low pH the water can start to leach high levels of lead from the pipes.
That was another issue regarding water treatment in Flint. The pH dropped from 8 to almost 7.3 in
less than a year and exacerbated the situation (Torrice, 2016).
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3 Methodology
A field study examined the lead concentrations in municipal drinking water (tap water) of
McDonald Engineering Building located in McGill University downtown campus, Montreal,
Quebec. The objective of the field study was to determine the range of lead concentrations in the
drinking water in order to assess compliance with regulatory guidelines and also to investigate the
factors that influence the lead concentration in drinking water. Ten water samples were selected
as a subset from a previous sample collection that was undertaken to check copper levels in McGill
University downtown campus buildings. The lead level analysed by ICP-MS technique. The
results are presented and correlated against the copper level, as copper is often used as an indicator
for lead.
3-1 Field survey
McDonald Engineering building, located in McGill University downtown campus, built in 1907,
and renovated in 1998, has been selected for this test. For the purposes of this report, the objective
of the sampling protocol is to determine possible exposure to lead in drinking water for the
consumers including the staff and students.
Note that a sampling protocol to assess the possible intake of lead will not capture the highest
concentrations of lead or the full contribution of lead from the lead service line. As discussed
earlier the concentration of lead in the water varies considerably as a result of factors including
contact time of the water to the lead containing parts of plumbing (stagnation), water chemistry,
and temperature. In this case two different types of samples were collected from the outlets:
stagnated, and one or five minute flushing. It should be noted that there is a large contribution of
particulate lead to the total lead concentration when water is left to stagnate for as little as 30
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minutes (Government of Canada, 2017). Flushed samples will identify lead leaching from any
fittings in the service line or other parts of the plumbing.
3-2 Sampling procedure
Prior to this study, 237 water samples were collected to test copper level in 6 different McGill
downtown campus buildings, 24 samples were from McDonald building. A stagnant and a running
water sample were taken from each sampling location. According consumption frequency, highuse water outlets from 1st and 4th floors were selected for sampling to improve the possible
identification of lead exposure.
Figure 5. McDonald Engineering building, McGill downtown campus
(Canadian Architecture Collection, 2019).
The aim of sampling was undertake lead analysis at points of consumption. Therefore the 10
samples of this collection were from different outlets from which water might be consumed:
kitchen tap, washroom tap, and water fountains (Figure 6). The collection of the samples took
place on Nov 2nd and 6th, 2018.
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First draw samples were taken in the morning to test the impact of week night stagnation. The
flushing samples were taken to compare with the stagnated samples and to check the effects of any
nearby lead fitting close to the tap (Table 10).
PH and temperature were also measured immediately after the samples were collected using a pH
6+ meter kit (Cole Parmer Oakton). All samples were taken in 125ml wide-mouth glass bottles
and preservation was performed by adding 5% nitric acid to maintain the pH below 2 to make sure
all the possible lead particles in every sample dissolve.
Table 10. Drinking water samples collected from different outlets.
Sample number
Stagnated / Flushed
MD-1-1-B-S
Stagnated
MD-1-1-B-1F
1 Minute Flushed
MD-4-3-S-S
Stagnated
MD-4-3-S-5F
5 Minute Flushed
MD-4-4-W-S
Stagnated
MD-4-4-W-5F
5 Minute Flushed
MC/D-B-1-F-S
Stagnated
MC/D-B-1-F-1F
1 Minute Flushed
MD-1-1-W-S
Stagnated
MD-1-1-W-1F
1 Minute Flushed
Description
Water fountain 1st floor
Water tap coffee room at 4th floor
Water tap washroom 4th floor
Water fountain at 1st floor McDonald-McConnell
Water tap washroom 1st floor
Figure 6. Water samples drawn from different water outlets in the building.
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3-3 Analyzing lead
As the concentration of the lead in drinking water was expected to be 1-40 ppb, the applicable
technique to analyze would be inductively coupled plasma-mass spectrometry (ICP-MS). This
method not only offers extremely low detection limits in the sub parts per trillion (ppt) range, but
also enables quantification at the high parts per million (ppm) level (Thomas, 2008). In this study
ICP-MS was utilized to measure the lead concentration of the collected samples at Eurofins
Environment Testing.
3-3-1 ICP-MS principles of measurement
The structure of the equipment is shown in Figure 7. Different compartments have different tasks
from the nebulizer to the detector which are explained briefly as follows.
Nebulizer: The sample, which usually must be in a liquid form, is pumped at 1 mL/min, usually
with a peristaltic pump into a nebulizer, where it is converted into a fine aerosol with argon gas at
about 1 L/min (Thomas, 2008).
Spray Chamber: The fine droplets of the aerosol, which represent only 1–2% of the sample, are
separated from larger droplets in this chamber (Thomas, 2008).
Plasma Torch: plasma is formed by the interaction of an intense magnetic field passing through
a copper coil on a tangential flow of argon gas, at about 15 L/ min flowing through a concentric
quartz tube (torch). This has the effect of ionizing the gas, which when seeded with a source of
electrons from a high-voltage spark, forms a very-high-temperature plasma discharge (~10,000 K)
at the open end of the tube (Thomas, 2008).
Interface Region: One of the most critical parts (vacuum of 1–2 torr), consists of two metallic
cones (usually nickel), called the sampler and a skimmer cone, each with a small orifice (0.6–1.2
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mm) to allow the ions to pass through to the ion optics, where they are guided into the mass
separation device (Thomas, 2008).
Ion Optics: So these parts function is to electrostatically focus the ion beam toward the mass
separation device, while stopping photons, particulates, and neutral species from reaching the
detector (Thomas, 2008).
Figure 7. ICP-MS diagram (Thomas, 2008).
Mass Analyzer: allows analyte ions of a particular mass-to charge ratio through to the detector
and to filter out all the nonanalytic, interfering, and matrix ions (Thomas, 2008).
Ion Detector: The final process is to convert the ions into an electrical signal with an ion
detector. The ions emerge from the mass filter, they impinge on the first dynode and are converted
into electrons. As the electrons are attracted to the next dynode, electron multiplication takes place,
which results in a very high stream of electrons emerging from the final dynode. This electronic
signal is then processed by the data-handling system in the conventional way and converted into
analyte concentration using ICP-MS calibration standards (Thomas, 2008).
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4 Results and discussion
The analysis of 10 drinking water samples was performed by Eurofins Environment Testing
Pointe-Claire using ICP-MS. The lead level in this data set has a median of 1 ppb which is below
the Canadian drinking water proposed MAC. In general, all the water taps and fountains meet the
safe lead level for drinking. Descriptive statistical parameters are shown in Table 12.
Table 11. ICP-MS results for the water samples collected from McDonald Engineering building, McGill downtown
campus.
Sample
number
MD-1-1-B-S
date
time
Pb (ppb)
Cu (ppm)
pH
Temperature
2018-11-02
6:21
<1
0.18
7.8
14.3
MD-1-1-B-1F
2018-11-02
6:24
<1
0.16
7.78
18.9
MD-4-3-S-S
2018-11-06
7:38
1
0.54
8.04
22.6
MD-4-3-S-5F
2018-11-06
7:44
<1
0.25
8.05
21
MD-4-4-W-S
2018-11-06
7:47
31
0.45
7.95
24.9
MD-4-4-W-5F
2018-11-06
7:54
3
0.31
7.87
30
MC/D-B-1-F-S
2018-11-02
6:52
<1
0.3
7.71
13.9
MC/D-B-1-F-1F
2018-11-02
6:54
<1
0.21
7.88
13.9
MD-1-1-W-S
2018-11-02
6:13
1
0.36
7.79
23.4
MD-1-1-W-1F
2018-11-02
6:17
1
0.32
7.81
22.2
All the water samples had lead levels that met the proposed MAC except MD-4-4-W-S (located in
ladies washroom on the fourth floor), which contained 6 times more lead than the standard
regulation concentration. This concentration suggests that there might be a lead fitting only inside
the plumbing structure of the ladies’ washroom on this floor, as the other samples showing
extremely low levels.
The 1st floor water fountain as well as the water fountain located on the 1st floor of the McDonaldMcConnell wing lead level were lower than the detection limit. The water tap in the coffee room
on the 4th floor was also safe in this regard.
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Two different scenario are presented in order to perform the data analysis.
1- All the samples with lead level less than 1 ppb are replaced by zero. Correlation analyses
measured the strength of relationship between two variables, lead and copper concentrations. As
the data sample set is small for this study, a ranked correlation between the paired data samples
was undertaken to determine if there is any identifiable relationship between the lead and copper
levels of the samples.
The median concentration of the data sample in this scenario is 0.5 ppb. The maximum lead level
was measured 31 ppb. The effect of flushing for five minutes is significant in this specific sample
as the concentration drops by a factor of ten.
Kendall’s tau and Spearman’s rank correlation coefficient were calculated using SPSS. The results
of this non-parametric correlation test is shown in Table 13. As found in both methods, the p-value
or significance level are high, which means there is statistically significant positive correlation
between lead and copper concentration.
The same test was run for pH and temperature to identify a correlation with the lead concentration.
There was no relationship between the lead level and pH measurements, however a strong positive
correlation with temperature has been found (Table 14).
2- All the samples with lead level less than 1 ppb were replaced by 1 ppb. The same procedures
were applied for this data set as well. The results only showed positive correlation between lead
concentration and temperature by Spearman’s method. No relationship has been found between
this modified data set and pH or copper concentration.
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Table 12. Descriptive analysis of the dataset.
Pb (ppb)
pH
Temperature (C)
Cu (ppm)
Valid
5
10
10
10
Missing
5
0
0
0
Mean
7.40
7.868
20.51
.308
Median
1.00
7.84
21.6
.305
Mode
1
7.71a
13.90
.16a
Std. Deviation
13.221
.113
5.309
.119
Variance
174.800
.013
28.188
.014
Minimum
1
7.71
13.9
.16
Maximum
31
8.05
30
.54
25
1.00
7.787
14.2
.202
50
1.00
7.84
21.6
.305
75
17.00
7.972
23.775
.382
N
Percentiles
a. Multiple modes exist. The smallest value is shown
Table 13. Kendall’s Tau and Spearman’s Rank Correlation Coefficient for copper and lead for the first scenario.
Kendall's tau_b
Cu (ppm)
Pb (ppb) (< 1 ppb = 0)
Cu (ppm)
Correlation Coefficient
1
.632*
Sig. (2-tailed)
.
0.019
10
10
Correlation Coefficient
.632*
1
Sig. (2-tailed)
0.019
.
N
10
10
Correlation Coefficient
1
.806**
Sig. (2-tailed)
.
0.005
10
10
Correlation Coefficient
.806**
1
Sig. (2-tailed)
0.005
.
10
10
N
Pb (ppb)
Spearman's rho
Cu (ppm)
N
Pb (ppb)
N
* Correlation is significant at the 0.05 level (2-tailed).
** Correlation is significant at the 0.01 level (2-tailed).
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Table 14. Kendall’s Tau and Spearman’s Rank Correlation Coefficient for temperature and lead for the first
scenario.
Kendall's tau_b
Pb (ppb)
Pb (ppb) (< 1 ppb = 0)
Temperature
Correlation Coefficient
1
.800**
Sig. (2-tailed)
.
0.003
10
10
Correlation Coefficient
.800**
1
Sig. (2-tailed)
0.003
.
N
10
10
Correlation Coefficient
1
.914**
Sig. (2-tailed)
.
0
10
10
.914**
1
Sig. (2-tailed)
0
.
N
10
10
N
Temperature
Spearman's rho
Pb (ppb)
N
Temperature
Correlation Coefficient
* Correlation is significant at the 0.05 level (2-tailed).
** Correlation is significant at the 0.01 level (2-tailed).
Table 15. Kendall’s Tau and Spearman’s Rank Correlation Coefficient for temperature and lead for the second
scenario.
Kendall's tau_b
Temperature
Pb (ppb)
Pb (ppb) (< 1 ppb = 1)
Temperature
Correlation Coefficient
0.548
1
Sig. (2-tailed)
0.051
.
N
10
10
Correlation Coefficient
1
0.548
Sig. (2-tailed)
.
0.051
10
10
Correlation Coefficient
.685*
1
Sig. (2-tailed)
0.029
.
N
10
10
Correlation Coefficient
1
.685*
Sig. (2-tailed)
.
0.029
10
10
N
Spearman's rho
Temperature
Pb (ppb)
N
* Correlation is significant at the 0.05 level (2-tailed).
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The sample number in this study was not large enough to extrapolate the results to the city of
Montreal. In order to make a representative sampling of
lead levels for Montreal, it is
recommended to divide the city into different zones based on the age of the buildings and time of
development of the areas. As lead was used in water pipes until 1975 and in soldering up to 1986,
separating the buildings by the year of construction will be useful to explore potential exposure.
Sampling all houses and buildings in the municipalities where it is suspected to have lead material
in their plumbing system, will provide a comprehensive representation of lead exposure.
Due to the small sample number in this study the results will not provide robust statistical values.
In addition the samples were taken from a very small number of buildings which do not represent
all buildings in which people work (due to the range in characteristics such as age of building,
geometry of distribution system, and water quality variation).
The positive correlation found between lead and copper is due to copper having been observed to
play a role in lead release in plumbing. Copper deposition onto lead surfaces in certain water
conditions (chlorinated and chloraminated) increases lead release. The copper deposits are
assumed to act as small galvanic connections on the lead surface. The solubility of copper is
directly correlated to copper deposition and release of lead (Federal-Provincial-Territorial
Committee on Drinking Water, 2018).
The correlation of lead with temperature indicates that with higher temperature the solubility of
the element increases as do many other metals. It is worth mentioning that the scales on lead pipes
vary and the pattern of lead release and temperature dependency sometimes vary based on lead
composition (Masters, Welter, & Edwards, 2016).
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There was no correlation between pH and lead level in this sample dataset. However the absence
of corrosion control in addition to low pH is the main concern for higher lead release (more study
is required to fully understand the process). In this sample set , the small number would have led
to a lack of correlation and, in addition, the pH range found was very small and slightly basic (the
range was [7.78 – 8.05], average = 7.87 and standard deviation = 0.11).
Another criteria that can be used to divide the city into sampling zone is to base it on the is the
potential lead exposure of vulnerable people, children in this case. To reach a robust and reliable
output regarding health impacts, it is recommended to sample drinking water from schools and
day cares in order to find the exposure to younger individuals as the health effects are more
damaging.
Several analytical methods such as graphite furnace atomic absorption spectrometry (GFAAS),
inductively coupled plasma-optical emission spectrometry (ICP-OES), and inductively coupled
plasma mass spectrometry (ICP-MS) are available for determination of lead concentration.
However, measuring heavy metals in water samples is difficult because of the low concentrations.
Low precision, low sample throughput, and requiring high level of operator skills are some of the
limitations for GFAAS. However it has great detection limit for lead (around 1 ppb), requires very
small sample size, and has low spectral interference.
ICP-OES has the ability to analyse multiple elements at the same time with high precision but the
main drawback for measuring lead with this method is the high detection limit (50 ppb) which is
not acceptable for this study.
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ICP-MS can measure all the samples and elements simultaneously, is easy to use, and has high
sensitivity with minimum detection limit of 1 ppb for lead. The main disadvantages of this method
is the high cost of the instrumentation.
Samples collected for this study are expected to contain very low lead levels. In order to detect
these low levels, a technique with suitable detection limit must be selected in order to explore the
lead concentration. Only the above lead measurement techniques are approved by the EPA. In this
study ICP-MS is utilised as the minimum detection limit for lead is 1 ppb and the instrument was
available for this purpose (via a commercial laboratory).
A similar study conducted by Deshommes, et al. (2016) at a large scale on lead levels in 78,971
water samples collected in four Canadian provinces from elementary schools, daycares, and other
large buildings were analyzed to provide lead concentration distributions. Maximum lead
concentration reached 13200 ppb and 3890 ppb after more than 6 hours and 30 min stagnation
periods, respectively, and the medians were calculated as 2.9 and 1 ppb, respectively.
Comparing the lead levels results from McDonald Engineering Building to Deshommes, et al.
(2016) report (Figure 8) shows the concentration of the lead in drinking water falls in 80th
percentile of this data set.
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Figure 8. Distribution of lead concentrations in the tap water of large buildings serving adults (7-99 yrs.) dataset
(Deshommes, et al., 2016).
The Government of Quebec also conducted 23,158 lead analyses from over 3,022 distribution
systems. All regulated water distribution networks should be controlled annually for lead
concentration and the number of samples to be taken per year is based on the number of people
served. The maximum lead concentration in these samples was 977 µg/L. 393 (1.7%) of the
analyses carried out exceeded the current standard of 10 µg/L while the median of results
exceeding the standard was 16 µg/L. 845 (3.6%) samples had higher concentrations than the
proposed Canadian recommendation of 5 µg/L (Government of Canada, 2017).
5 Conclusion
Lead in drinking water has adverse effects on human health, particularly for children, affecting
their intellectual abilities and behaviour. Due to its toxicity, lead has irreversible harmful effects
on neurological, cardiovascular, renal, and reproductive systems.
Lead has been used in drinking water distribution and plumbing systems for a long time as well as
in paints and as an additive in gasoline. A major reduction in the allowable levels of lead in
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products such as paints and its removal from gasoline mean that the primary sources for exposure
are through food and water.
Lead is present in drinking water as a result of dissolution from natural sources or from residential
or institutional plumbing systems containing lead in pipes, fitting solders or service connections.
Lead may be dissolved at rates that depend on several factors, such as water chemistry, and the
stagnation time. According to the Canadian Drinking Water Guidelines lead level in drinking water
should be as low as reasonably achievable as science cannot identify a level under which lead is
no longer associated with adverse health effects. The main strategy to reduce lead levels in drinking
water is to remove all the lead containing pipes, service lines, and fitting solders. Additionally,
flushing the tap water is promoted as a low cost approach to reducing lead exposures from drinking
water.
In the field study section of this report, the lead concentrations measured in drinking water in the
MacDonald Engineering Building of McGill University downtown campus in samples from 10
water outlets had values ranging from less than 1 ppb to 31 ppb.
In general, lead in tap water would not contribute to elevated lead exposure for the staff and
students working and studying in this building. The analysis also revealed an observation of
concern for the washroom tap on 4th floor (31 ppb). However, staff or students do not use the
washroom taps to fill their water bottles regularly so this might not pose any health risk.
A positive correlation was found between copper and lead and between temperature and lead when
the lead samples having concentrations less than 1 ppb were set to zero. There was no statistically
significant correlation between lead concentration and pH levels in the samples having pH levels
in the range of [7.78, 8.05].
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In conclusion, to minimize the exposure to lead from drinking water originating from plumbing
systems, it is recommended to consume the water after an appropriate period of flushing to reduce
the risk of any dissolved or particulate lead. Also cold water should be used for drinking and
cooking as the low temperature decreases the chance of any chemical reactions between the
plumbing system and the running or stagnated water. Last but not least, it is recommended to
utilize home water filtration system or portable pitchers to minimize any particulate heavy metal
introduced into drinking water.
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