A Canadian based study investigated the impact of air pollution in eight Canadian provinces from 1975 to 1994, based on measurement of nitrogen dioxide (NO2) and satellite observations. Nitrogen dioxide is a marker of traffic-related air pollution.
The study participants consisted of over 3,400 women and revealed an association between the risk of breast cancer and nitrogen dioxide. For post-menopausal women, the risk increased by 10% for each increase of 10 parts per billion (ppb) of NO2. The risk for premenopausal women increased by 32% for every additional 10 ppb of NO2.
“Air pollution is a complex mixture comprising hundreds of chemicals, some of which are toxic or carcinogenic,” said co-author Mark Goldberg, an environmental epidemiologist at McGill University. “NO2 is not carcinogenic, in itself, but it is an excellent marker for traffic-related air pollution.
“This study estimates the association between air pollution and breast cancer, but causality is far from established,” Goldberg cautions. “Many more studies would be needed in order for us to be able to make causal judgments.”
Exposure to traffic-related air pollution and the risk of developing breast cancer among women in eight Canadian provinces: A case–control study
Perry Hystad, Paul J. Villeneuve, Mark S. Goldberg, Dan L. Crouse, Kenneth Johnson, the Canadian Cancer Registries Epidemiology Research Group