Results show that more than 8,000 Canadian workers are potentially exposed to polychlorinated biphenyls (PCBs) at work; 97% of these workers are male. Industries with the largest numbers of exposed workers include specialty trade contractors (where most of the electricians are captured) and electric power generation, transmission and distribution. Other industries with notable worker exposure to PCBs are transportation equipment manufacturing and mining and oil and gas extraction (many industrial electricians are captured in both industries).
When exposure is examined by occupation, important occupational groups with the largest number of exposed workers include industrial electricians (3,000 exposed), electrical power line and cable workers (1,200 exposed), contractors and supervisors in electrical and telecommunication trades (1,100 exposed), electrical mechanics (800 exposed), and electricians (700 exposed).
Data Sources & Methods
Data used in developing the occupational estimates for polychlorinated biphenyls (PCBs) were collected from several sources:
- The Canadian Workplace Exposure Database (CWED) contains approximately 200 measurements for PCBs exposure. These measurements were collected during the years 1981 to 2004 in Ontario and British Columbia workplaces.
- Canadian and US scientific peer reviewed publications that addressed PCBs exposure in Canada and the United States.
- Grey literature including technical reports from governments and international bodies.
Prevalence Estimate Method
CAREX defines exposure to PCBs as inhalation exposure at work to levels likely to exceed non-occupational exposure via indoor or outdoor air.
To determine the number of workers potentially exposed to PCBs 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 PCBs.
- Occupations and industries at risk of possible exposure to PCBs were identified using any combination of data sources described above.
- The total number of workers in each identified occupation and industry intersection was obtained from Statistics Canada 2006 census data.
- 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.
- The number of workers in the identified group is multiplied by the assigned percentage to calculate the prevalence estimate of workers exposed to PCBs.