Recently published research in Occupational and Environmental Medicine concluded that women exposed to chemicals and pollutants (namely synthetic fibers and petroleum products) before their mid-thirties could treble their risk of developing breast cancer after their menopause.
There were more than 1100 fifty to 75 year old women in the sample and 556 of these were diagnosed with breast cancer following menopause in 1996 and 1997. The other 613 women matched for age and date of diagnoses had a range of other types of cancer and served as a comparison group.
A team of chemical and industrial hygiene experts investigated the level of exposure of the sample to about 300 potentially causal substances during their work career. After eliminating factors known to be associated with an increased risk of breast cancer, a link was found between occupational exposure to several of these substances. When the study sample was contrasted with the comparison group the risk of exposure peaked before age 36 and was magnified for each decade of exposure before that age. Results showed that women exposed to acrylic fibers had a seven-fold risk of breast cancer whereas those exposed to nylon fibers had almost a double risk.
When tumors were divided into those responding to different hormones, women whose cancers responded to estrogen but not progesterone were twice as likely to have breast cancer for every 10 year period of exposure to monaromatic hydrocarbons (a byproduct of crude oil) and rayon and acrylic fibers. For the group whose tumors responded to both estrogen and progesterone exposure to polycyclic aromatic hydrocarbons tripled their risk of cancer.
Although the authors concluded these results could be due to chance they are consistent with commonly used theoretical models. However, more research is needed to validate these findings.
