The industry with the largest number of workers exposed is recreation and amusement, which includes work at chlorinated swimming pools. Other industries with high numbers of workers exposed include services to building and dwellings (which includes specialized cleaners for swimming pools), sewage and other water systems, other schools and instruction industries, and pulp and paper mills.

The largest exposed groups by occupation are program leaders and instructors in recreation, specialized cleaners, chemical technologists and technicians, and water and waste plant operators.

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 chloroform were collected from several sources:

1. The Canadian Workplace Exposure Database (CWED) contains less than 50 measurements for chloroform exposure. These measurements were collected during the years 1982 to 2001 in British Columbia workplaces.
2. Canadian and US scientific peer reviewed publications that addressed chloroform 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 chloroform as inhalation exposure at work to levels which significantly exceed ambient background levels.

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

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