Highlights
- There are 3,540 to 6,510 new cancer cases each year in Ontario from exposure to 23 environmental carcinogens.
- Three environmental carcinogens—solar ultraviolet radiation, radon and fine particulate matter—accounted for over 90% of the total number of cancer cases from environmental exposures.
- These findings may inform policy and legislative priorities.
According to a new report called Environmental Burden of Cancer in Ontario, 3,540 to 6,510 new cancer cases each year in Ontario are from exposure to 23 environmental carcinogens. Over 90% of these cancer cases are the result of exposure to solar ultraviolet (UV) radiation, radon and fine particulate matter.
Solar UV radiation causes all major skin cancer types, including melanoma, the most fatal skin cancer.[1]The report, which was released by Cancer Care Ontario and Public Health Ontario, shows that an estimated 2,090 to 2,990 cancer cases per year are from solar UV radiation exposure in Ontario, representing, on average, about 80% of the province’s melanoma cases.
Radon is a naturally-occurring radioactive gas that is released during the decay of uranium in soil and causes lung cancer.[1][2]Ontarians are primarily exposed to radon from inhaling air inside buildings.[2] An estimated 1,080 to 1,550 cancer cases per year are from environmental radon exposure, which represents, on average, about 10% of Ontario’s lung cancer cases.
Fine particulate matter (PM2.5), which is defined as particles less than 2.5 micrometers in diameter and is one component of outdoor air pollution, has been classified as carcinogenic in humans, specifically causing lung cancer.[3]An estimated 290 to 900 cancer cases per year in Ontario are from environmental PM2.5. Exposure is caused by inhaling outdoor air pollution[4]from various sources, primarily motor vehicles and industrial facilities.
Eight other carcinogens each had an estimated burden of 10 or more cancer cases per year: arsenic, acrylamide, diesel particulate matter, asbestos, formaldehyde, second-hand smoke, TCDD (2,3,7,8-tetrachlorodibenzo-para-dioxin) and chromium (VI). The remaining 12 carcinogens examined in the report were estimated to each result in a burden of less than 10 cancer cases per year.[*]
The report examined exposure to these carcinogens from different sources, including being in the sun, breathing indoor and outdoor air, eating food, drinking water and ingesting indoor dust (relevant for small children). Workplace exposures were not assessed, even though many of them intersect with the environmental carcinogens examined in this report (e.g., exposure to asbestos in Ontario occurs primarily in the workplace). This report also did not assess exposures from specific behaviours (e.g., actively smoking cigarettes, use of tanning equipment).
Solar UV radiation, radon and PM2.5 are key areas of focus for prevention, given the large number of new cancer cases they are estimated to be responsible for. Potential interventions to reduce population exposure are outlined in the table below.
| CARCINOGEN | POTENTIAL INTERVENTION TO REDUCE EXPOSURE |
|---|---|
| UV |
|
| Radon |
|
| PM2.5 |
|