Woman's exposure to synthetic fibers and certain oil byproducts before mid-thirties triples a woman's risk of breast cancer after menopause, Canadian study says.

France Labreche of the National Institute of Public Health in Montreal found a strong link between higher rates of risk and exposure to several common synthetic materials, found in textile factories and other industrial settings.

Breast tissue is more susceptible to chemical toxins in women under 40.

Women occupationally exposed to acrylic fibers ran a seven-fold risk of breast cancer, while exposure to nylon fibers nearly doubled the risk.

Among breast cancer patients, those whose tumors responded well to estrogen treatment, but not progesterone treatment, were more than twice as likely to have breast cancer for every decade they were exposed to so-called monaromatic hydrocarbons -- a byproduct of crude oil -- and to acrylic or rayon fibers.

Exposure before the age of 36 to another class of hydrocarbons found in petroleum products tripled the risk for women whose tumors responded to both types of hormone treatment.

Estrogen and progesterone are both naturally-occurring hormones used in breast cancer treatment.

Compared to the non-breast cancer group, the risk peaked before the age of 36, when still-active cells in breast tissue are thought to be more sensitive to harmful chemicals.

Could wearing rayon and acryl clothes also pose a risk of breast cancer? There's no word about it.

Yet.