New report estimates burden of cancer in Ontario from environmental carcinogens

Between 3,540 and 6,510 new cancer cases in Ontario each year result from environmental factors, says a new report from Cancer Care Ontario and Public Health Ontario (PHO).

The report, Environmental Burden of Cancer in Ontario, estimates how many new cancer cases occur each year in the province as a result of exposure to cancer-causing agents, or carcinogens, that exist in our environment. The estimated burden of cancer from environmental carcinogens is significant, particularly when compared to other known cancer risk factors. The report found that environmental carcinogens represent roughly twice the cancer burden from drinking alcohol and about one-half the cancer burden from smoking.

"This report focuses on cancer-causing agents that Ontarians are exposed to every day simply by breathing, eating, drinking and being in the sun," says Dr. Ray Copes, chief ofenvironmental and occupational health, PHO. "Interestingly, three main carcinogens stand out as being particularly important - ultraviolet (UV) radiation from the sun, radon gas, and fine particle (PM2.5) air pollution."

The report ranks 23 environmental carcinogens according to the estimated annual number of new cancer cases in Ontario that each carcinogen would be associated with at current exposure levels. Key findings include:

• 2,090 to 2,990 new cancer cases from UV radiation in sunlight;
• 1,080 to 1,550 new cancer cases from radon;
• 290 to 900 new cancer cases from fine particles in outdoor air pollution.

"Understanding the factors that affect our cancer risk is an important step on the path to a healthier future. By focusing prevention efforts on the carcinogens associated with the highest number of new cancer cases, we can significantly reduce the environmental cancer burden in Ontario," says Alice Peter, director, population health & prevention, Cancer Care Ontario. "With this report, we can effect change through awareness of these environmental carcinogens; this will require the coordinated efforts and expertise from all levels of government, scientists, industry experts, non-governmental organizations and Ontarians."

Environmental Burden of Cancer in Ontario is the fifth report in Cancer Care Ontario's Cancer Risk Factors in Ontario series, and the first produced jointly by Cancer Care Ontario and PHO in the series.