|
| Main
| français
| CWHN home |
|
Download the PDF (456 KB, 22 Pages)
Safety and the Precautionary Principle Public Health vs. Profit Lessons from the Past - Ongoing Risks
|
|
Beyond DES – Hormones in the Environment This article is based on excerpts from Hormonal Pollution Alert: Protecting our Long-Term Health, Protecting the Environment by Ellen Reynolds, DES Action Canada
DES (diethylstilbestrol) exposure is often viewed as a health issue unique to those exposed to the drug and an issue that is no longer relevant. This is far from the truth. DES exposure and long-term exposure to any synthetic hormone concerns a much broader population than those directly exposed to DES. In fact, the entire population is exposed to synthetic hormones like DES, from sources such as chemical pollution, medicines, plastics, paints, and pesticides on food. Many synthetic chemicals in the environment are harmful to our health. Some are so-called "hormone disrupters" and mimic synthetic estrogens like DES. There has been strong evidence about the effects of these substances, but many questions are still unanswered.[1] By serving as a "human-effect model", the DES-exposed population demonstrates the potential effects of long-term exposure to synthetic hormones on the entire population and suggests answers to many of these questions. Animal studies linking DES and estrogen exposure to cancer date as far back as 1963.[2] The prevailing belief at the time, however, was that the effects found in animal studies did not translate to the human population. When cancer was eventually found in DES daughters, it was clear that the animal studies did in fact predict these cancerous changes much earlier. It had also been mistakenly accepted that the placental barrier was a protective guard for the embryo and fetus and that only radiation had the power to pass that barrier. Both DES and thalidomide proved that theory wrong. In both cases, the timing of the drug was a crucial factor. Some women took only very low doses (two or three tablets) of thalidomide during weeks five to eight of pregnancy, a crucial development period for the arms and legs of the fetus. Most of their babies were born with limb deformities or without limbs. Many women who were prescribed DES only took a small quantity of the drug during a critical period of sexual development of the fetus. Children exposed in utero before the 10th week of pregnancy experienced structural deformities and a greater risk of developing vaginal cancer. The DES tragedy demonstrates a unique lesson about longterm effects. The delayed and often hidden effects of DES exposure clearly illustrate the need for comprehensive testing of the long-term safety and effectiveness of prescription drugs. These effects also point to links between disease and long-term exposure to environmental synthetic hormones or endocrine distrupters This article is based on excerpts from Hormonal Pollution Alert: Protecting our Long-Term Health, Protecting the Environment by Ellen Reynolds, DES Action Canada long-term exposure to environmental synthetic hormones or endocrine disrupters. Endocrine Disrupters: What are They? Endocrine disrupters include many of the chemicals used in the production of plastics, pesticides, pulp, and paper. They are also produced as unintentional chemical by-products of industrial processes or waste incineration from landfill sites or toxic waste dumps. Endocrine disrupters are found in the air, water, and soil, and they accumulate in the fat tissue of wildlife and humans. From the list of known endocrine disrupters, the top 12, socalled Persistent Organic Pollutants, or POPs, have been identified by United Nations Environmental Programme as extremely toxic and are currently targeted for reduction and elimination internationally.[4] Very low levels of these toxic substances can affect drastic changes that may lead to cancer, problems with the nervous system, the immune system, and the reproductive system, especially for the fetus and young children. POPs "bio-accumulate" and magnify in concentration up the food chain. Endocrine disrupters interfere with the endocrine system in various ways, generally resulting in either an increase or decrease in the normal hormonal levels in the bloodstream. They may mimic or block hormones such as estrogen (female hormone) or androgen (male hormone) or interfere in other ways, including affecting the thyroid function. The end result is a mechanism that scrambles chemical messages (hormones) resulting in a variety of adverse health effects. Generally, the effects on wildlife include: the feminization of males, masculinization of females, deformities of reproductive organs, enlarged thyroid, birth defects, behavioural changes, weakened immune systems, and increased vulnerability to disease, including cancer. The most pronounced effects on wildlife are found in top predators due to bio-accumulation which is, of course, of great concern to humans as we are at the top of the food chain. Studying these effects on humans is made extremely difficult in an environment that is saturated with the natural hormones of our bodies and synthetic hormones from chemicals and medicines. Another problem is that there is no "control group" or unexposed group to use as a reference— everyone on the planet is exposed to endocrine disrupters. For this reason, it is extremely unlikely that scientists will ever be able to scientifically prove the exact connection between endocrine disrupters in the environment and the specific effects on humans. Some endocrine disrupters will cause an adverse effect in extremely low doses while higher doses will have no apparent effect. The reason for this is timing: by disrupting natural hormonal timing at critical moments of development, endocrine disrupters can potentially change the course of development and have drastic, life-long consequences. Certain hormone-related cancers have been linked to endocrine disrupters: prostate cancer (a 126% increase between 1973 and 1991 in the U.S.), breast cancer (1 in 9 women will develop breast cancer in her lifetime in North America), uterine cancer, ovarian cancer, and testicular cancer.[5] Also, cases of non-Hodgkin’s lymphoma, a cancer that can originate anywhere in the body, has almost tripled since the 1950s and is found in areas of high herbicide use, affecting farmers, herbicide applicators, and golf course supervisors.[6] Endocrine disrupters are the suspected cause of many problems related to fertility and the female reproductive system. Problems such as infertility, ectopic pregnancy, miscarriage, endometriosis, and lactation failure have all been linked to exposure to endocrine disrupters in animal studies. Endometriosis, a reproductive disease characterized by the growth of endometrial cells outside the uterus, has also been linked to endocrine disrupters. The Precautionary Principle For people who have been exposed to DES, many questions remain about further exposure to synthetic estrogens or other synthetic hormones. For example, it is unknown how DES daughters react to oral or injectable contraceptives, fertility drugs, or hormone replacement therapy. For this reason, specialists suggest it may be safer to avoid further exposure to synthetic hormones when possible. Based on the experience of the DES-exposed population and the harmful effects of this government-approved drug, drug regulators should be applying the precautionary principle to long-term drug testing and safety, and governments should be applying it to the regulation of synthetic hormones in the environment. Hormonal Pollution Alert: Protecting our Long-Term Health,
Protecting the Environment first appeared in the form of a
public education resource kit containing 10 fact sheets. It
also appeared, in part, in the DES Action Newsletter, Issue
65, Spring 2001. Both documents are available from DES
Action Canada, 5890 Monkland Avenue, Suite 203,
Montreal, Quebec H4A 1G2, toll-free 1-800-482-1-DES,
http://www.web.net/~desact.
NOTES [1] For an elaboration of this issue, see Colborn T, Dumanoski D, Myers JP. Our Stolen Future. New York: Dutton, 1996. [2] Dunn T, Green, A. Cysts of the epididymis, cancer of the cervix, granular cell myoblastoma, and other lesions after estrogen injection in newborn mice. Journal of the National Cancer Institute 1963;31:425-38. [3] United Nations Environmental Programme (UNEP), 1998. [5] Epstein SS. The Politics of Cancer Revisited. USA: East Ridge Press, 1998. [6] Steingraber S. Living Downstream: An Ecologist Looks at Cancer and the Environment. New York: Addison-Wesley, 1997; 52-53. |
| This page updated |
