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 / Chromium III / Chromium VI / 1,2-dichloroethaneEthylbenzene / Methylene chloride / Nickel / Oil mist
Radiation / Crystalline silica / Sulphuric acid / Trichloroethylene
Welding fume
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):
Table 1. ACGIH & IARC Categorized Carcinogenic Agents Tested in the Study
Agent / Carcinogenicity CategoryACGIH / IARC
Cadmium / A2 / 1
Chromium (III) / A4 / Metallic & compounds – 3
Chromium (VI) / A1 / 1
1,2-dichloroethane (solvent) / A4 / 2B
Ethylbenzene (solvent) / A3 / 2B
Methylene chloride (solvent) / A3 / 2B
Nickel / Elemental – A5
Soluble inorganic – A4 / Ni compounds – 1
Metallic & alloys – 2B
Oil mist / Pure, highly refined – A4 / 3
Radiation / n/a / 1
Silica (crystalline) / A2 / 1
Sulphuric acid / A2 / 1
Trichloroethylene (solvent) / A2 / 1
Welding fumes / 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 / IARCA1 – Confirmed Human Carcinogen / 1 – Carcinogenic to Humans
A2 – Suspected Human Carcinogen / 2A – Probably carcinogenic to humans
A3 – Confirmed Animal Carcinogen / 2B – Possibly carcinogenic to humans
A4 – Not Classifiable as a Human Carcinogen / 3 – Not classifiable as to its carcinogenicity to humans
A5 – Not Suspected as a Human Carcinogen / 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.
Table 3. Cancer Types Associated with Agents Tested in the Study.
Agent / CancersCadmium / Lung and prostate
Chromium (III) / Lung
Chromium (VI) / Lung, gastro-intestinal tract
1,2-dichloroethane / Non-Hodgkin’s lymphoma, liver
Ethylbenzene / Liver, kidney
Methylene chloride / Lung, liver
Nickel / Lung & nasal passages
Oil mist / Bladder, prostate
Radiation / Upper digestive tract, lymphoma, non-Hodgkin’s lymphoma, prostate
Silica (crystalline) / Lung
Sulphuric acid / Lung, laryngeal
Trichloroethylene / Bladder, ovarian, kidney, liver, prostate, rectal
Welding fumes / Central nervous system, lung, prostate, skin
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 / Flowrate (LPM*) / Analytical MethodMetals scan (includes welding fumes, nickel, cadmium and chromium III) / 2.0 / NIOSH** Method 7300
Hexavalent chromium / 2.0 / NIOSH Method 7600
Crystalline silica / 2.75 / NIOSH Method 7602 or 7500
Oil mist / 2.0 / NIOSH Method 5026
Organic solvents (1,2-dichloroethane, ethylbenzene, methylene chloride, trichloroethylene) / 0.2 / NIOSH Method 1501M
Sulphuric acid / 0.2 / NIOSH Method 7903
Radiation (thorium) / 2.0 / NIOSH Method 7300
*LPM = litres per minute, **NIOSH = National Institute of Occupational Safety & Health
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.
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.
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.
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.