Exposure to certain chemicals and pollutants before a woman reaches her mid-30s could treble her risk of developing post-menopausal breast cancer, suggests research published in Occupational and Environmental Medicine. Women exposed to synthetic fibers and petroleum products during the course of their work seem to be most at risk, the researchers say.
The researchers based their findings on more than 1100 women, 556 of whom were diagnosed with breast cancer in 1996/7 in Montreal, Canada, when aged between 50 and 75. A team of chemists and industrial hygienists then set about investigating the women's levels of exposure to around 300 different substances throughout the course of their employment history.
Interestingly, the risk peaked for exposures before the age of 36, and was magnified with each additional decade of exposure before this age. This resulted in women occupationally exposed to acrylic fibers running a seven-fold risk of breast cancer, while those exposed to nylon fibers almost doubled their risk.
The researchers say the findings are consistent with the theory that breast tissue is more sensitive to harmful chemicals if the exposure occurs when breast cells are still active - in other words, before a woman reaches her 40s.
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Source: British Medical Journal