Trichloroethylene Occupational Exposures

Trichloroethylene Occupational Exposures

Overview

Inhalation and dermal contact are the most important routes of occupational exposure to trichloroethylene.[1]

CAREX Canada estimates that approximately 7,600 Canadians are exposed to trichloroethylene in their workplaces. The largest industrial groups exposed are personal and household goods repair and maintenance, fabricated metal product manufacturing, and printing and related support activities. The largest occupational groups exposed are industrial painters, coaters, and metal finishing process operators; tailors, dressmakers, furriers and milliners; metalworking and forging machine operators; and labourers in metal fabrication. Many of these occupations involve metal degreasing; workers who degrease metals tend to be the most heavily exposed occupational group.[1]

Prevalence Estimate

Results show that approximately 7,600 Canadians are exposed to trichloroethylene (TCE) in their workplaces; 68% of these workers are male. The largest industrial groups exposed are personal and household goods repair and maintenance (where upholsterers and furniture refinishers are exposed by using TCE as a spot treatment or cleaning solvent), fabricated metal product manufacturing, and printing and related support activities.

The largest occupational groups exposed are industrial painters, coaters, and metal finishing process operators (1,100 workers exposed); tailors, dressmakers, furriers and milliners (1,000 workers exposed); metalworking and forging machine operators (760 workers exposed); and labourers in metal fabrication (720 workers exposed).

The number of workers exposed to trichloroethylene decreased by approximately 2,300 workers from 2006 to 2016 (a 23% decrease). This was primarily driven by a decrease in the number of workers in the manufacturing industry.

Workers exposed to trichloroethylene by industry in 2016

Workers exposed to trichloroethylene by region in 2016

Click the second tab to view total number of workers exposed.

* = < 50 workers

Level of Exposure

In total, approximately 7,600 Canadians are exposed to trichloroethylene in their workplaces. The majority of workers exposed to TCE are in the low and moderate exposure category. A small number of trichloroethylene-exposed workers are at risk for high exposure.

Workers exposed to trichloroethylene by exposure level in 2016

Level of exposure by industry

Identifying industries with either 1) workers exposed to high levels of trichloroethylene or 2) a larger number of workers exposed to trichloroethylene is important in guiding cancer prevention efforts to prioritize exposed groups and target resources most effectively.

The table below shows the number of workers exposed by industry group and level of exposure to trichloroethylene. These results highlight industries with the largest number of exposed workers, as well as industries with the highest levels of exposure. For example, in the repair and maintenance industry, most of the workers fall into the moderate exposure category, and has a large number of workers exposed in that industry. Depending on the goals of a prevention campaign, exposure reduction in the large industrial group might be a useful strategy, or reducing exposure to those at highest risk of exposure could be seen as a priority.

Workers exposed to trichloroethylene by exposure level and industry in 2016

*Numbers may not add up due to rounding

Methods and Data

Our Occupational Approach page outlines the general approach used to calculate prevalence and exposure level estimates for workplace exposures.

Data Sources

Data used in developing the occupational estimates for Trichloroethylene (TCE) were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains approximately 1,600 measurements for TCE exposure. These measurements were collected during the years 1981 to 2004 in Ontario and British Columbia workplaces.
  2. Canadian and US scientific peer reviewed publications that addressed TCE exposure in Canada and the United States.
  3. Grey literature including technical reports from governments and international bodies.

Prevalence Estimate Method

CAREX defines exposure to TCE as inhalation or dermal exposure at work to levels likely to exceed non-occupational exposure from urban air or due to the use of household products that contain TCE (i.e. hobby adhesives, cleaners, and sealants).

To determine the number of workers potentially exposed to TCE at work, CAREX occupational exposure experts used methods previously established in other peer-reviewed CAREX projects in Europe. A series of steps were taken to assign exposure proportions to occupations and industries at risk of exposure to TCE.

  1. Occupations and industries at risk of possible exposure to TCE were identified using any combination of data sources described above.
  2. The total number of workers in each identified occupation and industry intersection was obtained from Statistics Canada 2016 census data.
  3. A percentage of workers exposed was assigned to that occupation and industry intersection. Percentages were determined by consultation with existing evidence in the data sources, previously established methods from the Europe CAREX estimates and the expert judgement of CAREX occupational hygienists.
  4. The number of workers in the identified group is multiplied by the assigned percentage to calculate the prevalence estimate of workers exposed to TCE.

Exposure Level Method

CAREX uses available workplace exposure measurements in the CWED to create exposure level categories by industry and occupation. For trichloroethelyne, these categories are:

Category 1: Low Exposure

A group of workers (people in the same job category and industry) is put in this exposure category for one of two reasons:

  1. The are no valid measurements, but a hygienist identified this group as typically exposed during literature and other reviews;
  2. There are valid exposure measurements in the CWED and a hygienist review determined that exposure is plausible; AND EITHER:
    1. There are less than 10 samples available in the CWED, OR
    2. There are ≥10 measurements available but they do not meet the criteria for Moderate Exposure.

Category 2: Moderate Exposure

A group of workers is put in this exposure category if:

  1. There are at least 25 individual samples in the CWED, AND
  2. 20% or more samples have a value higher than 5 ppm (which is half the current occupational exposure limit for trichloroethylene).

OR

  1. There are at least 10, but less than 25, individual samples in the CWED, AND
  2. 20% or more samples have a value higher than 10 ppm (which is the current occupational exposure limit for trichloroethylene).

Category 3: High Exposure

A group of workers is put in this exposure category if both these criteria are met:

  1. There are at least 25 individual samples in the CWED, AND
  2. 20% or more samples have a value higher than 10 ppm (which is the current occupational exposure limit for trichloroethylene).
Sources

1. International Agency for Research on Cancer (IARC). IARC monograph summary, Trichloroethylene, Volume 106 (2014) (PDF)

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