In the1990s a study was conducted of PCB and DDE (a breakdown product of DDT) in 15,000 New York City women who had had mammograms. The blood of breast cancer patients contained 35% more PCB and DDE than that of healthy women, and the women with the highest DDE levels were four times as likely to have cancer than women with lowest levels. In 1993 Dr. Devra Davis and others reported on an investigation of estrogen mimics and breast cancer: “Established risk factors for breast cancer, including genetics, account for at best 30% of cases…Recent epidemiological studies have found that breast fat and serum lipids (fats) of women with breast cancer contain significantly elevated levels of chlorinated organics compared with non-cancer controls As the proportion of inherited breast cancer in the population is small, most breast cancers are due to acquired mutations.” Dr. Sarah Janssen, a staff scientist at NRDC, stated that more than 70% of breast cancer cases appear to be rooted in lifestyle or environmental causes, rather than genetics, and more than 200 chemicals are known either to alter or to cause tumor formation in rodent breast tissue. In most cases, if a rodent gets breast cancer from a specific chemical, a woman will also.
The linkage between breast cancer and environmental toxins is supported by the Breast Cancer Fund’s 2010 report, “The State of the Evidence: the connection between breast cancer and the environment.” Laboratory evidence supports at least three biological mechanisms that may link environmental pollutants and breast cancer. Chemicals that show these types of biological activity are ubiquitous environmental pollutants which are common in workplaces, consumer products, and building materials. Many of these chemicals are so-called endocrine disrupters or hormone disrupters because they mimic or otherwise alter the activities of natural hormones, especially estrogens (e.g., estradiol and progesterone). These substances also affect a wider group, including testosterone, adrenal hormones, and thyroid hormones. Despite the lack of a formal classification of many of these chemicals as carcinogens (i.e., known to produce cancers in humans), a substantial body of scientific literature implicates many of these chemicals in the current high rates of breast cancer…Bisphenol-A (BPA) has been associated with an increased risk of breast and prostate cancer, reproductive and neurological disorders. CDC researchers have measured BPA in 93 percent of urine samples from 400 adults. It has been found in the blood and urine of pregnant women, in amniotic fluid of pregnant women, and in placental tissue and umbilical cord blood at birth. BPA is an endocrine-disrupting chemical that, even in very small amounts, can affect health, particularly when exposure occurs during gestation and early in life. Doses in parts per billion and even parts per trillion have been shown to have effects on laboratory animals and human breast cells. Mammary cells are more susceptible to the detrimental effects of hormones and chemicals during early stages of development, from the prenatal period through puberty and adolescence, and on until a woman’s first full-term pregnancy. Prenatal exposures of mice to BPA led to the appearance of neoplastic (precancerous) lesions in the mammary glands.”
Postscript for the men. There is a natural inclination to inquire about links of prostate cancer to environmental toxics, and I haven’t seen any. A June 2011 note by the Mayo Clinic staff states that the cause is not known; it is simply stated that it begins with abnormal DNA in some cells of the prostate.