Air pollution has already been linked to a range of health problems. A new Canadian study suggests pollution from traffic may put women at risk for another deadly disease. The study, published in the journal, Environmental Health Perspectives, by researchers from The Research Institute of the MUHC, McGill University and Université de Montréal links the risk of breast cancer – the second leading cause of death from cancer in women – to traffic-related air pollution.
“We’ve been watching breast cancer rates go up for some time, “says study co-author Dr. Mark Goldberg, a researcher at The RI MUHC. “Nobody really knows why, and only about one third of cases are attributable to known risk factors. Since no-one had studied the connection between air pollution and breast cancer using detailed air pollution maps, we decided to investigate it.”
Goldberg and his colleagues approached the problem by combining data from several studies to create two air pollution “maps” showing levels of nitrogen dioxide (NO2), a by-product of vehicular traffic, in different parts of the city in 1996 and 10 years earlier in 1986.
Then, they charted the home addresses of women diagnosed with breast cancer in a 1996-97 study onto the air pollution maps. Their findings were startling. The incidence of breast cancer was clearly higher in areas with higher levels of air pollution.
“We found a link between post-menopausal breast cancer and exposure to nitrogen dioxide (NO2), which is a ‘marker’ for traffic-related air pollution”, says Goldberg. “Across Montreal, levels of NO2 varied between 5 ppb to over 30 ppb. We found that risk increased by about 25 per cent with every increase of NO2 of five parts per billion. Another way of saying this is that women living in the areas with the highest levels of pollution were almost twice as likely to develop breast cancer as those living in the least polluted areas.”
Dr. France Labrèche, of the Université de Montréal said, “From a public health standpoint, this possible link also argues for actions aiming at a reduction of traffic-related air pollution in residential areas.”