Results show 38,000 workers were occupationally exposed to ionizing radiation in 2005; 57% of these workers were male. The largest industrial group exposed was medicine*, where exposure was from the use of ionizing radiation for diagnostic and therapeutic purposes. More women than men were exposed to ionizing radiation in the medical industry while more men were exposed in all other industries listed. On an occupation basis, the largest groups exposed were medical radiation technologists (3,000) and nurses (1,600).
*Data from the National Dose Registry is not available by industry in the same way as census data, hence industry names here do not match those used in other occupational estimates. In addition, proportions of industry exposed numbers are not included, also due to data incompatibility.
Data Sources & Methods
The 2005 National Dose Registry (NDR) survey data were used in developing the occupational estimates for ionizing radiation. The survey contains ionizing radiation exposure monitoring data for over 150,000 Canadian workers collected in 2005 and the results are available in two separate NDR annual reports published in 2006 and 2007.
Prevalence Estimate Method
CAREX defines exposure to ionizing radiation as having an annual ionizing radiation dose of > 0 mSv (millisievert) in the 2005 NDR survey.
The number of workers with measured dose of > 0 mSv in the 2005 NDR survey was totalled to obtain the number of exposed workers in Canada. Exposure in different industries was calculated by counting the total number of exposed workers in different job categories in the survey. Exposure proportion in each industry was calculated by dividing the total number of workers reported in different job categories by the number of exposed workers in each job category. Assuming that the job category exposure proportions are similar for all jobs in all provinces, the number of exposed workers by province was calculated by multiplying the exposure proportions in different industries with the number of workers sampled in each job category in each province (available from the survey), then adding the number of exposed workers across all job categories for each province.