Did you read about the groundbreaking breast cancer study released recently? Here's the idea behind this case-controlled occupational research: Study one thousand women with breast cancer in neighboring communities of southern Ontario who work in a variety of occupations including plastics manufacturing and automotive plants. Conduct in-depth interviews and surveys and take exhaustive 10-year work histories to figure out which chemicals the women are exposed to on the job.
At the same time, study another thousand women from the same communities who do not have breast cancer.
Discover that the women who work in plastics and food-canning have a staggering fivefold increase in pre-menopausal breast cancer. Take a look at the chemicals these workers are likely to be exposed to, and what do you find? Endocrine-disrupting compounds -- including phthalates, bisphenol A (BPA) and flame retardants -- that lab studies have shown to cause mammary gland changes and tumors.
In this remarkable Canadian study, published in the peer-reviewed journal Environmental Health, the researchers meticulously eliminated other possible explanations (like smoking, physical activity, alcohol use and reproductive history) and were left with the conclusion that the chemicals the women were exposed to were a decisive factor in increasing breast cancer risk.
This research is about real women working in real high-risk occupations and suffering real breast cancer. That puts a face on biological plausibility, a scientific measure of association between a cause and an outcome. In this study, the science is telling us that exposure to various chemicals classified as endocrine disruptors over a period of time is causally linked to breast cancer. This association is quite plausible not only because the study was especially well done but also because it confirms and adds to the growing, compelling body of evidence that endocrine disruptors are linked to breast cancer.
Unfortunately for these women workers and for all of us (for we too are exposed to some of these chemicals on a daily basis), many industry and government leaders refuse to act based on biological plausibility. Instead, they prefer plausible deniability, saying we need more and more and more evidence -- incontrovertible truth, in fact -- before we take action. They argue that there is no incontrovertible proof of direct harm from any one chemical at the exposure levels that have been codified in the sad and sorry occupational safety regulations of our country and many others around the world. They ignore that these workers, and indeed all of us, are exposed to multiple chemicals, individually and in mixtures, over long periods of time, often including particularly vulnerable stages of life like pregnancy and lactation when harm is more likely. They ignore that low doses of some chemicals such as BPA can do more harm than higher doses at certain stages of development. By ignoring the growing evidence and not taking action on these causal links, they are missing a critical opportunity to prevent this disease in at least some of the hundreds of thousands of women who are diagnosed every year.
This refusal to act based on biological plausibility -- this clinging to plausible deniability -- is unacceptable. These women should not have to face a cancer diagnosis because of the work they do. And none of us should have to face this devastating disease because industry and government failed to protect us.
So will industry and government leaders in Canada and the United States agree that this study provides sufficient evidence that plastics and canning workers who come into daily contact with a range of carcinogens and endocrine-disrupting compounds face life-threatening health risks? Will they take quick, decisive steps to protect these women? Will they work urgently to enforce existing laws and to overhaul our broken chemicals management system so that workers and all of us are protected? While that is certainly plausible, it will take incredible political, social and personal will. I'm calling on our leaders to find that will. These women workers deserve nothing less.