> Environmental and Health Concerns > Carcinogens and Xenoestrogens

Between 1938 and 1971, a wonder drug was prescribed extensively by physicians to pregnant mothers. It was said to prevent miscarriage and premature births. By 1953 it was proved that the drug, an oral synthetic nonsteroidal estrogen called diethylstilbestrol (DES), did not prevent miscarriages.

The drug was prescribed, however, until 1971, when the FDA issued a warning regarding the disastrous consequences on children who were exposed to DES before birth. From epididymal (testicular) cysts, undescended or small testes, to a possible higher incidence of testicular cancer in men exposed to DES as fetuses, to structural reproductive-tract abnormalities and premenopausal clear-cell adenocarcinoma (malignant tumours) in women, DES was every parent’s nightmare. DES has estrogen-like effects and is part of a class of dangerous chemicals called endocrine disruptors.

Endocrine disruptors or xenoestrogens are defined as exogenous (external) substances that can interfere with the functions of the endocrine system, causing adverse health effects in the organism directly exposed to it or in its offspring. According to the authors of Stolen Future: Are We Threatening Our Own Fertility, Intelligence, and Survival? A Scientific Detective Story (Penguin Groups, 1996), there are over 45 chemicals that are known to act as hormone disruptors. These man-made chemicals, routinely and intensively used, and found in herbicides, fertilizers, and plastics, have been discovered to leak hormone-like substances.

Silent Killers

There is a general rule when it comes to buying food: If the ingredient list contains items that are impossible to even pronounce, steer clear. Yet, unbeknownst to many consumers, their shopping carts may contain a sinister collection of harmful, hard-to-pronounce chemicals, which are deemed useful by the agricultural industry: pesticides, fertilizers, and insecticides. All are widely used by conventional agriculture to help crops grow and livestock flourish. Most, if not all, threaten life. Most are endocrine disruptors or xenoestrogens and can easily wreak havoc with the hormonal pathways of both people and animals.

DDT, an organochlorine pesticide widely used in the 1950s and 1960s, has xenoestrogenic effects and strong carcinogenic effects in mice. Its main metabolites, p,p’- DDE and p,p’- DDD are both carcinogenic. Since a lot of the cancers occurring in women are hormonally mediated, there is a high probability that xenoestrogenic substances such as organochlorine pesticides contribute to the onset of cancer. Several early studies showed that the fat tissues of patients with breast cancer had increased concentrations of DDT and its metabolites, an association that has since been disputed but not disproven. Mothers of men with testicular cancer also showed high blood levels of organochlorine contaminants. Studies like these have led scientists to conclude that there may well be a link between environmental chemicals such as pesticides and testicular development problems, including low sperm counts and testicular cancer.

Problematic PCBs

Polychlorinated biphenyls (PCBs), another class of organochlorine chemicals, are now banned due to their deleterious effects on wildlife and human health. Organochlorine chemicals accumulate in the fat tissues of the human body. As with other chemicals present in the environment, PCBs undergo bioaccumulation, and their concentration in the body may exceed that in the environment. PCBs have been defined as endocrine disruptors or xenoestrogens.

Mainly used in paints, plastics, rubbers, pigments, and dyes, PCBs are flame resistant, highly stable, and have electrical insulating properties. PCBs are not easily degradable and can travel long distances in the air, affecting areas and organisms far away from the releasing site. Not only that, PCBs travel up the food chain, so larger organisms ingest larger amounts of PCBs because of prior contamination of their food sources. Although their production was halted in 1976, PCBs are still present in the environment. They are present in meat, fish, shellfish, poultry, milk and dairy products, and fruits and vegetables.

Daniela Ginta, MSc, is a freelance writer. She writes on natural health and parenting topics and teaches science-related topics at a local post-secondary school.

Source: alive #284, June 2006