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Female Breast Cancer and the Environment

Breast cancer is the most commonly diagnosed cancer in women in the United States. Breast cancer will develop in approximately one in eight women during their lifetime. The incidence of this disease has changed very little in recent years. The disease usually occurs in women, but men can have breast cancer too.

Only about 47% of breast cancers that occur in the United States can be attributed to established risk factors. Although animal studies indicate that environmental contaminants can cause breast tumors, clear links between environmental exposures (other than ionizing radiation) and human breast cancer have not been established.

Exposure to chemicals such as poly aromatic hydrocarbons, benzene, and organic solvents and secondhand smoke have been suspected in causing breast cancer, but the evidence is weak and more research is needed.

Pesticides and industrial products in food packaging and consumer products concern researchers because of their pervasive presence in the environment, ability to be absorbed by fat, and potential to act as endocrine disruptors. An endocrine disruptor is a synthetic chemical that when absorbed into the body either mimics or blocks hormones and disrupts the body's normal functions. Research continues into the link between these chemicals and breast cancer.

Exposure and Risk

The exact causes of breast cancer are unknown; however, women in certain categories are at increased risk for breast cancer. Known risk factors include:

  • Older age
  • White ethnicity
  • Obesity (after menopause)
  • Dense breast tissue (after menopause)
  • High estrogen levels
  • Unusually tall
  • Early onset of menstruation
  • Later age pregnancy
  • Having no or few children
  • Late onset of menopause
  • Family history of breast cancer
  • Certain genetic mutations
  • Certain types of benign breast disease
  • History of breast cancer
  • Post-menopausal hormone use
  • Heavy alcohol consumption
  • Cigarette smoking
  • Exposure to secondhand cigarette smoke
  • Current or recent use of birth control pills
  • Low levels of physical activity
  • Never breast feeding or short duration of breast feeding
  • Exposure to radiation to the chest
  • Prenatal exposure to diethylstilbestrol (DES)
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Among women whose risk is higher than average, certain drugs may help prevent breast cancer. All women should discuss their risk and screening or prevention options with their doctor.

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