Are they killing us?
Daniela Ginta, MSc
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. These man-made chemicals, routinely and intensively used, and found in herbicides, fertilizers, and plastics, have been discovered to leak hormone-like substances.
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.
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.
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.
In 1987 the International Agency for Research on Cancer (IARC) classified PCBs as probable carcinogens, with sufficient evidence of carcinogenicity in animals but limited evidence in human studies. The Environmental Protection Agency (EPA) also classified PCBs as probable carcinogens in 1996. A recent study published in Environmental Health Perspectives (January 2006) has confirmed a higher incidence of brain cancer in people who held jobs that exposed them to PCBs. Women who are exposed to PCBs have a high risk of developing both melanomas and brain cancer. Studies show a higher incidence of deaths from different types of cancers in people who are exposed to PCBs.
A Necessary Evil?
Plastics, so widely used, are yet another major source of xenoestrogens. Some of the estrogen mimics that leak from plastics and plasticizers include bisphenol-A (BPA) and phthalates. BPA is used in flame retardants and resins; the latter is found in dental fillings, water containers, baby bottles and other types of polycarbonate bottles, and food and beverage linings. Repeated use of plastic food containers is associated with BPA leaking into the food. Microwaving plastic containers makes xenoestrogens leak even more into the food or drinks they contain. Several studies have shown that prenatal exposure to BPA in rats resulted in reduced daily sperm production, increased prostate gland size in male offspring, and appeared to cause accelerated growth and puberty.
Phthalates are present in medical equipment made with polyvinyl chlorine plastics, as well as baby mattresses, and they are also found in paints and personal care products. Two studies published in 2003 by a Harvard team showed an association between phthalates and DNA damage in human sperm, and more recent studies have established a link between prenatal exposure to this type of xenoestrogens and male reproductive-tract defects.
How Low is Too Low?
Although still contentious, the issue of declining sperm output is not to be ignored, according to a study published in Human Reproduction in 2001. Men exposed to pesticides had higher blood estradiol concentrations than appropriate controls who were less exposed, and their sperm output was below the limit for male fertility. Scientists concluded that environmental factors may be a cause for infertility and even worsen fertility problems that already exist.
A larger, more disputed study published in 1992 by a team of Danish scientists analyzed data on human sperm concentrations from a number of studies published over a 50-year span and concluded that the average male sperm count had dropped 45 percent from 1940 to 1990.
Since lifestyle and sexual behaviour could not explain the big difference in numbers, a better explanation is that environmental estrogens—chemical xenoestrogens—are responsible for declining sperm levels and decreased fertility rates.
Minimize Your Exposure to Xenoestrogens
Source: Thanks to Dr. Cristine Craig, ND, for providing the majority of these tips.