Researchers from the University of Sterling in Scotland conducted a study in Canada of 1,100 women, half of whom had already been diagnosed with breast cancer. The researchers found that women with the disease were nearly three times more likely to have been farm workers, most during adolescence.
Toxic pesticides and other farm chemicals may be responsible for changes in the women's developing breasts that eventually led to breast cancer, the researchers concluded, because developing breast tissue is especially vulnerable to exposure to toxins during teenage years.
According to professor Andrew Watterson, a researcher in the study, roughly 4 percent of all cancers are related to a woman's occupation. Watterson and colleagues found that the risk of breast cancer was highest among women who worked or lived on farms during adolescence, then went on to work in the auto or health industries.
According to the study's authors, certain chemicals involved in farm work, as well as chemicals in the auto and health industries, could be linked to cancer.
"Nurses and other healthcare workers are potentially exposed to ionizing radiation... drugs, anesthetic waste gases, and viruses possibly associated with cancer risk," the researchers wrote. "A number of hormonally active chemicals are, or have been, used in medicine and laboratory work." The study's authors added that a wide range of solvents is commonly used in the car manufacturing business.
However, cancer epidemiology specialists are skeptical of the study, which claims environmental chemicals are partly responsible for rising breast cancer rates. Henry Scowcroft, science information officer at Cancer Research UK, says Watterson's study involved too few subjects to draw any firm conclusions.
"Breast cancer is on the rise in Western society," Scowcroft said. "All the available scientific evidence shows this increase is largely down to changes in lifestyle factors. Scientists have also looked at whether environmental toxins might also contribute to the increase in breast cancer, but have found no conclusive link."
Watterson and his team of researchers have acknowledged that the link between farm and other environmental toxins and breast cancer should be more thoroughly studied.