Tetrachloroethylene Occupational Exposures

Tetrachloroethylene Occupational Exposures

Overview

Inhalation is the most important route of occupational exposure to tetrachloroethylene.[1]

CAREX Canada estimates that approximately 11,000 Canadians are exposed to PERC in their workplaces.

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The largest industrial groups exposed include dry cleaning and laundry services, printing and related support activities, and traveller accommodation. The largest occupational groups exposed to tetrachloroethylene include dry cleaning, laundry and related occupations, printing press operators, metalworking and forging machine operators, and labourers in metal fabrication. Workers performing metal degreasing, producing fluorocarbons, and producing chemicals are also at risk of exposure totetrachloroethylene.[2]

Prevalence Estimate

Results show that approximately 11,000 Canadians are occupationally exposed to tetrachloroethylene (often referred to as perchloroethylene, or PERC); 62% of these workers are male. The largest industrial groups exposed include dry cleaning and laundry services and printing and related support activities (where tetrachloroethylene is a common solvent in printing inks and is also used in the preparation of flexoprint plates and washing rollers). There are notable differences in industrial groups by sex; the largest number of women exposed is in dry cleaning and laundry services (1,300 women exposed, or 66% of all workers exposed in this industry). In printing support, the industry with the largest number of exposed men, only 400 women are exposed (21% of all workers exposed).

When examining exposure to tetrachloroethylene by occupation, the largest groups of workers exposed include dry cleaning, laundry and related occupations (1,400 workers exposed), printing press operators (1,200 workers exposed), metalworking and forging machine operators (740 workers exposed), and labourers in metal fabrication (700 workers exposed).

The number of workers exposed to tetrachloroethylene decreased by approximately 3,700 workers from 2006 to 2016 (a 25% decrease). This was primarily driven by a decrease in the number of workers in the manufacturing industry, and in particular, in printing and related support activities, fabric mills, and textile product mills.

Workers exposed to tetrachloroethylene by industry in 2016

Workers exposed to tetrachloroethylene by region in 2016

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

* = < 50 workers

Level of Exposure

In total, approximately 11,000 Canadians are exposed to tetrachloroethylene (PERC) in their workplaces. The majority of workers exposed to PERC are in the low exposure category. A smaller number of PERC-exposed workers are at risk for moderate exposure, but few are at risk of high exposure.

Workers exposed to tetrachloroethylene by exposure level in 2016

Level of exposure by industry

Identifying industries with either 1) workers exposed to high levels of PERC or 2) a larger number of workers exposed to PERC 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 PERC. These results highlight industries with the most number of workers, as well as industries with the highest levels of exposure. 

For example, in the printing industry, all of the 1,900 workers fall into the low exposure category. However, in the personal and laundry services industry (where dry cleaning businesses are situated), a majority of the workers are in the moderate exposure categry. 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 tetrachloroethylene 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 tetrachloroethylene were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains approximately 5,000 measurements for tetrachloroethylene 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 tetrachloroethylene 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 tetrachloroethylene as inhalation exposure at work to levels above those expected in the general environment (this may not include people who live above dry-cleaning establishments that use PERC, however).

To determine the number of workers potentially exposed to tetrachloroethylene 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 tetrachloroethylene.

  1. Occupations and industries at risk of possible exposure to tetrachloroethylene 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 tetrachloroethylene.

Exposure Level Method

CAREX uses available workplace exposure measurements in the CWED to create exposure level categories by industry and occupation. For tetrachloroethylene (PERC), 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 12.5 ppm (which is ½ of the current occupational exposure limit for tetrachloroethylene),

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 25 ppm (which is the current occupational exposure limit for tetrachloroethylene).

Category 3: High 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 25 ppm (which is the current occupational exposure limit for tetrachloroethylene).
Sources

1. International Agency for Research on Cancer (IARC). IARC monograph summary, Volume 63 (1995) (PDF)
2. National Toxicology Program (NTP). 14th Report on Carcinogens for Tetrachloroethylene (2016) (PDF)

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