Results show that 7,200 Canadians are exposed to vanadium pentoxide in their workplaces; 94% of these workers are male. Industries with the greatest numbers of exposed workers are fabricated metal products, boiler, tank and shipping container manufacturing, services to buildings, iron and steel mills and ferro-alloy manufacturing, and oil and gas extraction.
When exposure is examined by occupation, boilermakers and welders are groups with greatest number of workers exposed to vanadium pentoxide (3,800 and 1,000 exposed, respectively). Exposure during welding activities, however, is expected to be low. Other important jobs are specialized cleaners (this represents people who are contract cleaners for boilers and flues), labourers in mineral and metal processing and utilities, industrial mechanics, and artisans and craftpersons (exposed via the use of vanadium pentoxide in glass).
Data Sources & Methods
Data used in developing the occupational estimates for vanadium pentoxide were collected from several sources:
- The Canadian Workplace Exposure Database (CWED) contains approximately 600 measurements for vanadium pentoxide 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 vanadium pentoxide exposure in Canada and the United States.
- Grey literature including technical reports from governments and international bodies.
Prevalence Estimate Method
CAREX defines exposure to vanadium pentoxide as inhalation or dermal exposure to the compound above levels encountered in the general environment.
To determine the number of workers potentially exposed to vanadium pentoxide 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 vanadium pentoxide.
- Occupations and industries at risk of possible exposure to vanadium pentoxide 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 vanadium pentoxide.