14 DAY TRIAL // A brand new, daring Montreal study suggests that there is a connection between pollution from traffic and an increased risk of breast cancer in women.
The study has been carried out by researchers from The Research Institute of the MUHC (RI MUHC - Dr. Mark Goldberg), McGill University (Drs. Goldberg, Dan Crouse and Nancy Ross), and Université de Montréal (Dr. France Labrèche).
We all know that traffic emissions pollute the air, the polluted air invades our lungs and if we keep breathing it for a while, then our body gets intoxicated and our health declines.
The researchers have found that the risk of breast cancer, which is the second cause of death from cancer in women, is linked to traffic-related air pollution.
Study co-author Dr. Mark Goldberg, a researcher at The RI MUHC, and his colleagues, got to these results by combining data from several previous studies.
First of all they wanted to chart the pollution in different areas of Montreal, so they used data from their 2005-2006 study, assessing levels of NO2 – nitrogen dioxide, in several parts of the city in 1996 and 1986.
Then they made a map of the home addresses of women who were diagnosed with breast cancer in 1996-1997, and when they combined the data, they found that the incidence of breast cancer was far higher in areas with higher levels of pollution.
Dr Goldberg said that the survey revealed “a link between post-menopausal breast cancer and exposure to nitrogen dioxide (NO2), which is a ‘marker’ for traffic-related air pollution”.
“Across Montreal, levels of NO2 varied between 5 ppb to over 30 ppb, and 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.”
The scientists have been following the increase of breast cancer rates for a while now and they say that “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.”
Even though this new study reached to this worrying conclusion, all the results must be considered with caution, Dr Goldberg says.
The study is not saying that NO2 is what causes breast cancer, as in traffic polluted areas, there are several other gases, particles and compounds, some of which are carcinogenic.
The researchers also say that this type of study can also contain some errors, and even though they tried to account for the majority of them, there are still some areas than can cause problems.
“For example, we don’t know how much the women in the study were exposed to pollution while at home or at work, because that would depend on their daily patterns of activity, how much time they spend outdoors and so on,” explains Dr. Goldberg.
Dr. Labrèche adds that there are several studies in the US that have also shown possible links between air pollution and cancer, but no on is in a position of saying that breast cancer is caused by air pollution.
At most, the possible links deserve further investigation and it can also be a good reason to reduce traffic-related pollution in residential areas.
The study was funded by two research grants: one from the Canadian Cancer Society and another one from the Canadian Institutes of Health Research (CIHR), as reported by AlphaGalileo.