Practical Health and Safety Solutions
121 Keedian Drive, East St. Paul, MB R2E 0K3
Phone (204) 668-3141 Fax (204) 654-9583
Email: winnipegairtesting@shaw.ca
Workers Compensation Board of Manitoba
September 2013
RE: EXPOSURES TO CARCINOGENS IN THE AEROSPACE INDUSTRY
RESEARCH AND WORKPLACE INNOVATION PROGRAM 2011
Executive Summary
Winnipeg Air Testing received funding through the WCB Research and Innovation
Program in order to perform testing on worker exposure to carcinogens in the
aerospace industry, given its large presence in Manitoba industry. The study
commenced with an extensive literature review and several agents of concern,
identified in aerospace industry, were noted, such as metal working fluids,
trichloroethylene and hydrazine. There was also historical evidence of increased
cancer rates in workers in the industry based on data from other jurisdications.
Five companies agreed to participate in this study with Winnipeg Air Testing. These
companies were the larger companies in the aerospace industry and have the
majority of the employees and industrial processes in the industry. Initial discussions
with these companies, held to develop sampling strategies, revealed that most had
already identified the risks associated with some of the cancer causing agents and
had therefore previously performed internal investigations in order to substitute these
products with non-cancer causing agents. This revelation greatly reduced the number
of cancer causing agents that had been identified in the literature search; however,
the following cancer causing agents were identified at each of the five companies:
Cadmium
Ethylbenzene
Radiation
Welding fume
Chromium III
Methylene chloride
Crystalline silica
Chromium VI
Nickel
Sulphuric acid
1,2-dichloroethane
Oil mist
Trichloroethylene
Samples for detecting the presence of these cancer-causing agents were collected
using approved analytical methods. Sampling included both airborne and on surfaces
as well as skin exposure testing. Airborne testing was performed to detect the
presence of metals (from welding fumes, plating and painting), hexavalent chromium,
crystalline silica, oil mist, organic solvents (1,2-dichloroethane, ethylbenzene,
methylene chloride, and trichloroethylene) sulphuric acid and radiation (thorium from
welding rods). Surface sampling was performed to detect the presence of nickel,
chromium and acids while skin exposure testing was completed on gloved workers to
detect solvent breakthrough.
Overall, the presence of the tested carcinogens in these aerospace workplaces, in the
majority of the samples collected both airborne and surface, was measured at very low
concentrations that were generally well below the allowable exposure of each of the
tested chemicals.
Only one overexposure was measured for a worker that was using methylene chloride
(organic solvent) during a part cleaning process. As this process is not performed on a
regular basis, additional sampling to could not be performed prior to the completion of
this study. However, additional testing in this area of concern was recently completed
for this workplace to confirm the initial findings determined during this study. If levels
continue to remain elevated, recommendations will be provided to help lower the
worker’s exposure to methylene chloride.
1.0
Background
Funding was received through the WCB Research and Innovation Program in order to
perform testing on worker exposure to carcinogens in the aerospace industry, given its
large presence in Manitoba industry. Several agents of concern were noted in a
literature review that was performed for the application process, such as metal working
fluids, trichloroethylene (TCE) and hydrazine.
Five companies agreed to participate in this study with Winnipeg Air Testing. Initial
discussions with these companies, held to develop sampling strategies, revealed that
most had already identified the risks associated with some of the cancer causing agents
and had already performed internal investigations in order to substitute these products
with non-cancer causing agents. This finding greatly reduced the number of cancer
causing agents that had been identified in the literature search; however, a few cancer
causing agents were identified at each of the five companies, and are summarized in
the following table. The table also provides the carcinogenicity category of each agent
provided by the American Conference of Governmental Industrial Hygienists (ACGIH)
and International Agency for Research on Cancer (IARC):
2
Table 1. ACGIH & IARC Categorized Carcinogenic Agents Tested in the Study
Agent
Cadmium
Chromium (III)
Chromium (VI)
1,2-dichloroethane
(solvent)
Ethylbenzene
(solvent)
Methylene chloride
(solvent)
Nickel
Oil mist
Radiation
Silica (crystalline)
Sulphuric acid
Trichloroethylene
(solvent)
Welding fumes
Carcinogenicity Category
ACGIH
IARC
A2
1
A4
Metallic & compounds – 3
A1
1
A4
2B
A3
2B
A3
2B
Elemental – A5
Soluble inorganic – A4
Pure, highly refined – A4
n/a
A2
A2
Ni compounds – 1
Metallic & alloys – 2B
3
1
1
1
A2
1
n/a
2B
The following provides a description of the ACGIH and IARC categories for
carcinogenicity:
Table 2. Description of ACGIH & IARC Carcinogenicity Categories.
ACGIH
IARC
A1 – Confirmed Human Carcinogen
A2 – Suspected Human Carcinogen
A3 – Confirmed Animal Carcinogen
A4 – Not Classifiable as a Human Carcinogen
A5 – Not Suspected as a Human Carcinogen
1 – Carcinogenic to Humans
2A – Probably carcinogenic to humans
2B – Possibly carcinogenic to humans
3 – Not classifiable as to its carcinogenicity to humans
4 – Probably not carcinogenic to humans
The literature review that was performed, which included a review of ACGIH TLV
documentation, had identified various types of cancer associated with the agents listed
in Table 1. The following table provides a summary of the cancer types associated with
each agent.
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Table 3. Cancer Types Associated with Agents Tested in the Study.
Agent
Cancers
Cadmium
Chromium (III)
Chromium (VI)
1,2-dichloroethane
Ethylbenzene
Methylene chloride
Nickel
Oil mist
Lung and prostate
Lung
Lung, gastro-intestinal tract
Non-Hodgkin’s lymphoma, liver
Liver, kidney
Lung, liver
Lung & nasal passages
Bladder, prostate
Upper digestive tract, lymphoma, non-Hodgkin’s lymphoma,
prostate
Lung
Lung, laryngeal
Bladder, ovarian, kidney, liver, prostate, rectal
Central nervous system, lung, prostate, skin
Radiation
Silica (crystalline)
Sulphuric acid
Trichloroethylene
Welding fumes
2.0
Methodology
2.1
Airborne Chemicals
Worker exposure to airborne chemicals was evaluated using primarily personal
monitoring and some area monitoring. The sampling pumps worn by welders were
located on the workers so as to collect air from their breathing zone using “in-mask”
sampling systems for welders. The sampling pumps worn by the other workers and
placed for area samples were also located on the workers so as to collect air from the
workers’ breathing zone.
The samples were collected using normal industrial hygiene sampling pumps. The
sampling pumps were calibrated both before and after the survey to ensure a reliable
flowrate. The flowrates used for each chemical and laboratory analytical method has
been summarized in the following table.
Chemicals
Metals scan (includes welding
cadmium and chromium III)
Hexavalent chromium
Crystalline silica
fumes,
nickel,
Oil mist
Organic solvents (1,2-dichloroethane, ethylbenzene,
methylene chloride, trichloroethylene)
Sulphuric acid
Radiation (thorium)
Flowrate
(LPM*)
2.0
Analytical Method
NIOSH** Method 7300
2.0
2.75
2.0
NIOSH Method 7600
NIOSH Method 7602
or 7500
NIOSH Method 5026
0.2
NIOSH Method 1501M
0.2
2.0
NIOSH Method 7903
NIOSH Method 7300
*LPM = litres per minute, **NIOSH = National Institute of Occupational Safety & Health
4
The metals samples were analyzed for 14 metals. The use of a metal scan in this
manner is useful in fully evaluating the metal present in a complex work environment.
This type of analysis ensures that no metal component of the exposure is missed and it
can also demonstrate analytically that other suspect metals are not present in the
workplace environment.
Silica samples are based on the respirable fraction of airborne silica dust. Accordingly,
a cyclone was placed in front of the cassette for these samples that allow only the
respirable fraction of the airborne dust to reach the filter for subsequent analysis.
2.2
Surface Sampling – Nickel, Chromium & Acids
Chromium surface wipe samples were collected based on the methodology described
in NIOSH 9100 “Lead in Surface Wipe Samples”. The surface samples were collected
using GhostWipesTM (Environmental Express) and a 10cm x 10cm square plastic
template.
The wipe samples were analysed using EPA (Environmental Protection Agency)
Analytical Method 6010C.
3M Chromate Check swab were also used to detect the presence of chromium on
various surfaces.
Acid surface samples were collected from various surfaces using a cleaner/developer
solution and colourimetric SWYPEs.
2.3
Skin Exposure Solvent Sampling
Skin exposure to solvents was determined using Permea-Tec Sensors that were
attached on the worker’s dominant hand, after gloving, in three different areas: thumb,
middle finder and palm. The workers were then asked to double glove the hand with
the sensors and proceed to perform normal working tasks throughout a period of
approximately one hour. Solvent breakthrough would be detected by a colour change
from the sensors.
3.0
Results
3.1
Airborne Chemicals
The results of airborne chemicals were compared to the 2012 Threshold Limit Values
(TLVs). TLVs represent time-weighted average airborne concentrations to which it is
believed that a worker can be exposed, 8 hours per day, 40 hours per week, without
adverse effect. TLVs have been adopted in the Safety and Health legislation as the
allowable exposure guidelines in Manitoba.
5
3.1.1 Welding Fume Metals
Welding typically generates a possible exposure to a number of different metals. Any
possible additive effects resulting from exposure to different metals were considered in
the exposure calculation. If a worker is exposed to more than one agent that produces
the same physiological response or acts upon the same organ of the body, the
combined effect of the total exposure must be considered. The chemicals were grouped
into common health effects. The dominant health effect was used in interpreting the
significance of the exposures. That is to say that the health effect which recorded the
highest sum of exposure relative to the permissible exposure limit was the dominant
health group.
For the study, a total of 39 welders were tested for welding fume metals. Overall,
exposure to metals for the welders were not elevated and ranged from 3 to 62% of
the allowable exposure.
TIG welding was performed by 30 welders that had exposures ranging from 3 to 41%
of the allowable exposure. Local exhaust ventilation (LEV) was present for 23 of
these welders, which had metals exposure ranging from 3 to 24% of the allowable
exposure. Exposure to the remaining 7 TIG welders that did not have LEV ranged
from 10 to 41% of the allowable exposure.
MIG welding was performed by 5 welders, two of which had LEV present at their
workplace. Metals exposures for the 2 welders having LEV were both 6% of the
allowable exposure, while exposures for the remaining 3 welders (no LEV) ranged
from 10 to 62% of the allowable exposure.
A combination of TIG and MIG welding was performed by 4 welders that did not have
LEV. Metals exposure for these 4 welders ranged from 17 to 31% of the allowable
exposure.
3.1.2 Paint & Plating Metals
The presence of chromium (III) was identified in one of the paints used at one of the
facilities used for this study. As such, two area samples of airborne chromium (III) were
collected in the Paint Department. Chromium (III) exposure in both area samples was
0.3% of the allowable exposure.
Carcinogenic metals (nickel, cadmium, chromium (III) and hexavalent chromium (VI))
were used in various plating processes in some of the tested facilities. Two personal
and four area samples were collected for hexavalent chromium, all of which had
concentrations that were less than the analytical level of detection or <0.6% to <0.8% of
the allowable exposure.
6
Three area samples were also collected for chromium (III) in a Plating department that
used chromium based plating baths. The concentration of all samples was less than the
analytical level of detection or <0.3% of the allowable exposure.
Six personal and four area samples were also collected in a Plating department that
used chromium, nickel and cadmium-based plating baths. Any possible additive effects
resulting from exposure to different metals were therefore considered in these exposure
calculations. Personal exposures varied from 6 to 8% of the allowable exposure, while
area exposures varied from 6 to 16% of the allowable exposure.
3.1.3 Crystalline Silica
A total of 18 workers were tested for crystalline silica exposure. Overall, the silica
exposure for all workers varied from less than 10% to less than 20% of the allowable
exposure, which signifies that all silica concentrations were below the analytical level
of detection.
3.1.4 Oil Mist
One personal and two area samples for oil mist were collected as part of the study.
The oil mist exposure for the two areas and one personal sample was less than 3%
of the allowable exposure, which signifies that all exposure concentrations were
below the analytical level of detection.
3.1.4 Organic Solvents
Six personal and twelve area samples for organic solvents were collected, with the
following solvents of specific interest for this study: 1,2-dichloroethane, ethylbenzene,
methylene chloride, and trichloroethylene.
The presence of 1,2-dichloroethane was detected in eight of the area samples, ranging
from 1.5 to 45.6% of the allowable exposure. Its presence was also detected in four of
the personal samples, ranging from 2.2 to 7.2% of the allowable exposure.
The concentration of ethylbenzene in all personal and area samples was below the
analytical level of detection.
The presence of methylene chloride was detected in five area samples, ranging from
0.4 to 13.7% of the allowable exposure. Its presence was also detected in three
personal samples, ranging from 0.5 to 141.6% of the allowable exposure. No local
exhaust ventilation was present in the area that yielded the highest personal exposure
value.
The presence of trichloroethylene was detected in two area samples, ranging from 3.5
to 4.1% of the allowable exposure. Its presence was also detected in one personal
sample and was at 4.8% of the allowable exposure.
7
3.1.5 Sulphuric Acid
Five personal and nine area samples for sulphuric acid were collected. The exposure
to all personal and area samples was less than the analytical level of detection, ranging
from <14 to <35% of the allowable exposure.
3.1.6 Radiation during Welding (thorium)
The airborne concentration of radiation was measured for a group of seven welders
that use a radioactive thorium rod. Radiation exposure to all seven welders was less
than the analytical level of detection.
3.2
Surface Sampling
Manitoba’s Safety and Health legislation has not adopted acceptable surface level
guidelines for chemicals, given that surface samples are rarely used to evaluate
workers’ exposure profiles, resulting in insufficient data to develop appropriate
acceptable surface levels.
As such, the surface wipe sample results were compared to recommended
acceptable surface levels obtained from the Brookhaven National Laboratory (BNL),
Safety & Health Services Division, Industrial Hygiene Group, Surface Wipe Sampling
Procedure (May 10, 2011). BNL has developed surface wipe criteria levels for
various metals, which have been calculated based on the ratio of TLV and the United
States Department of Labor’s Occupational Safety and Health Administration (OSHA)
Permissible Exposure Limit (PEL) (i.e. TLV/PEL airborne) to the US Department of
Energy’s Beryllium housekeeping criteria.
3.2.1 Metals Surface Sampling (chromium and nickel)
A total of eighteen surface samples were collected to detect the presence of
chromium in some of the Plating departments. Only one sample yielded a
concentration that was above BNL’s Acceptable Surface Level value.
Eleven surface samples were also collected to detect the presence of nickel. The
concentration of nickel on all samples was below BNL’s acceptable level value.
3.2.2 Acid Surface Sampling
Four area samples were selected and surface tested for the presence of acids at one
of the study locations. The areas were selected based on the location of the acid
baths and in areas where workers may not be wearing protective gloves, such as
hand railings at access points to the acid baths. Acids were detected in two of the
four samples.
8
3.2.3 Radiation Surface Sampling
Some of the companies work on engines and airplane components from military or
international sources. Some parts were received that had been used in the area of
the disabled nuclear reactors in Japan. The concern was that some of the parts may
have surface contamination of radioactive material on them when they enter the
plant.
Surface testing was performed on 6 components as they come in over time during
the study. None of the units had elevated radiation levels or measurable surface
contamination on them.
As this was identified as an ongoing need, a system was put in place to allow the
company to perform the tests in-house on an as needed basis. The components of
the in-house system were as follows:




procedures to assess and record the results of an assessment
numerical guidelines for acceptable readings and elevated readings
procedures to be followed in the event of finding an elevated result on a
component
recommendations for equipment to be used to perform the assessments
The company has since purchased the radiation detection equipment and the
program is now operating in-house as suspect units are received.
3.3
Skin Exposure Solvent Sampling
Eleven workers were selected and fitted with Permea-Tec Sensors in order to detect
potential solvent breakthrough from the gloves used at the time of this survey. For all
workers, no breakthrough was detected from the Permea-Tec Sensors.
4.0
Conclusion
Overall, the presence of the tested carcinogens in these aerospace workplaces, in the
majority of the samples collected both airborne and surface, was measured at very low
concentrations that were generally well below the allowable exposure of each of the
tested chemicals.
Only one overexposure was measured for a worker that was using methylene chloride
(organic solvent) during a part cleaning process. As this process is not performed on a
regular basis, additional sampling to could not be performed prior to the completion of
this study. However, additional testing in this area of concern was recently completed
for this workplace to confirm the initial findings determined during this study. If levels
continue to remain elevated, recommendations will be provided to help lower the
worker’s exposure to methylene chloride.
9
The results of the surface testing also suggests that the cleaning procedures used by
these aerospace facilities is adequate, as the presence of the various chemicals tested
were generally detected at very low concentrations. The results of this study also
indicates the importance of wearing adequate gloves in areas located both near and
further away from plating baths.
The findings of this study clearly indicates that the aerospace industry in Winnipeg has
gone to great lengths to either eliminate or reduce the number of carcinogens used by
workers throughout the various processes used at these facilities.
Sincerely
Winnipeg Air Testing
Per
Douglas N. Wylie, CIH, ROH, CRSP,CRM
Occupational Hygienist
Léo Jr. Nicolas, M.Sc.,CIH,P.Ag.
Occupational Hygienist
10