Occupational exposure to certain chemicals in young women may raise their risks of breast cancer after menopause.  France Labreche, from Institut de Recherche Robert Sauve (Quebec, Canada), and colleagues examined 556 women with breast cancer, ages 50 to 75 years, matching them to a comparable number of women who served as controls. The team discovered an increased risk of breast cancer with occupational exposure to certain chemicals. In particular, exposure to synthetic fibers, common in the textile industry, carried a sharply elevated risk of postmenopausal breast cancer. For each 10-year increase in duration of exposure before age 36, acrylic fibers were associated with a nearly eight-fold risk of breast cancer, and nylon fibers were associated with a doubled risk.  The team also found associations with breast cancer for early exposure to polycyclic aromatic hydrocarbons (PAHs) from petroleum and other sources. When they analyzed breast cancer by tumor status, the researchers found that exposure to PAHs from petroleum tripled the risk of breast cancer among those with estrogen- and progesterone-positive tumors. Writing that: “Certain occupational exposures appear to increase the risk of developing postmenopausal breast cancer,” the researchers posit that: “Breast tissue is more sensitive to adverse effects if exposure occurs when breast cells are still proliferating. More refined analyses, adjusting for hormonal receptor subtypes and studies focusing on certain chemical exposures are required to further our understanding of the role of chemicals in the development of breast cancer. “