Dichloromethane Occupational Exposures

Dichloromethane Occupational Exposures

Overview

Inhalation is the most important route of occupational exposure, however dermal absorption is also possible.[1] CAREX Canada estimates that approximately 22,000 Canadians are exposed to dichloromethane in their workplace.

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The largest industrial groups exposed are automotive repair and maintenance, followed by building finishing contractors and plastic product manufacturers. Other important industries that are likely exposed include building equipment contractors and personal and household goods maintenance and repair.

The largest exposed occupational groups are motor vehicle body repairers, followed by painters and decorators, construction traders helpers and labourers, and machinist and machining and tooling inspectors. Other occupations that may be exposed include furniture refinishers and chemical manufacturers.[1] Workers may be exposed when spraying urethane foam, removing paint or varnish from equipment or furniture, or using products that use dichloromethane as a propellant or degreasing agent.

Prevalence Estimate

Results show that approximately 22,000 Canadians are exposed to dichloromethane in their workplaces; 85% of these workers are male. The largest industrial groups exposed are automotive repair and maintenance, building finishing contractors and plastic product manufacturers, building equipment contractors, and personal and household goods maintenance and repair.

The largest exposed occupational groups are motor vehicle body repairers (3,900 workers exposed), painters and decorators (1,900 workers exposed), construction traders helpers and labourers (1,700 workers exposed), and machinist and machining and tooling inspectors (1,200 workers exposed).

The number of workers exposed to dichloromethane decreased by approximately 3,200 workers from 2006 to 2016 (a 13% decrease). This was primarily driven by a decrease in the total number of workers in the plastics manufacturing industry.

Workers exposed to dichloromethane by industry in 2016

Workers exposed to dichloromethane by region in 2016

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

* = < 50 workers

Level of Exposure

In total, approximately 22,000 Canadians are exposed to dichloromethane in their workplaces. The majority of workers exposed to dichloromethane are in the low exposure category. A substantial number of dichloromethane-exposed workers are at risk for moderate and high exposure.

Workers exposed to dichloromethane by exposure level in 2016

Level of exposure by industry

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

For example, in the automotive service technicians industry, all of the workers fall into the low exposure category. However, machine operators in the chemical, plastics and rubber processing industry are mostly in the high exposure category (76%). 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 dichloromethane 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 dichloromethane (DCM) were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains over 5,100 measurements for DCM 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 DCM 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 DCM as inhalation or dermal exposure at work to levels significantly greater than those encountered in outdoor or indoor air due to short term use of formulated products.

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

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

Exposure Level Method

CAREX uses available workplace exposure measurements in the CWED to create exposure level categories by industry and occupation. For dichloromethane, 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 25 ppm (which is ½ of the current occupational exposure limit for dichloromethane),

OR

  1. There are at least 10 individual samples in the CWED, AND
  2. 4. 20% or more samples have a value higher than 50 ppm (which is the current occupational exposure limit for dichloromethane).

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. 2. 20% or more samples have a value higher than 50 ppm (which is the current occupational exposure limit for dichloromethane).
Sources

1. National Toxicology Program (NTP). 14th Report on Carcinogens for Dichloromethane (2016) (PDF)

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