Estrogen is a female reproductive hormone; it is involved in the development of female sexual organs and the regulation of a woman's monthly cycle. Many environmental chemicals compete with, or mimic, estrogen. This means that they can be absorbed into human bodies and can affect certain tissues and organs in a similar fashion as estrogen. But they do not break down in the body the way that natural hormones do. On the contrary, synthetic estrogens are stored in fatty tissues, they can persist for a long time, and they can be present at much higher levels than their naturally produced counterparts. Because of their properties as a female reproductive hormone, artificial chemicals that act as estrogen-like hormones can impact parts of the body which are most sensitive to hormonal fluctuations - the reproductive organs of both men and women. The growth in serious disorders in male reproduction is now being traced to increasing levels of exposure to synthetic estrogen-like hormones.
Dr. Theo Colburn, a senior scientist with the World Wildlife Fund, believes these effects center on the hormonal, or endocrine system. "As I began looking again at the literature closely there were at least 16 top predator species in the Great Lakes that were showing reproductive problems, population decline, fertility problems, immune problems, all developmental problems - offspring, young chicks born with adult plumage. Something went wrong during that embryonic development..."
According to Professor Louis Guillette of the Department of Zoology at the University of Florida: "In every [alligator] nest there was something wrong with the eggs. The scientists found traces of a weak estrogenic chemical, DDE, which was contaminating the eggs." Today, 75% of the alligator eggs are dead or infertile. Males that do survive are demasculinized, with a high level of a female hormone, and low levels of male hormones. 25% have a penis that is so small that they can not mate, and they will never reproduce. "Similar changes have been found in the turtles from this lake. Many males have become inter-sexed (hermaphroditic) with reproductive organs more like a female, with high levels of female hormones." 20% of the animals in Lake Apopka have this inter- sex condition. "We are not finding normal males."
In the United Kingdom, hermaphroditic fish are found near sewage outfalls. In an experiment, male fish were left for three weeks in cages at 28 different sewage outfalls throughout Britain. The astounding results were that when these fish were tested they were found to have huge amounts of female hormones in their blood. "These males in effect were changing sex." Nonyl phenol was found in both the river water (50 micrograms per liter or higher) and in the sewage outfalls. Tests on fish confirmed that nonyl phenol produces a very high estrogenic effect on male fish. In addition, studies of rats have found decreased testicle size in male rats exposed to 30 micrograms per liter of nonyl phenol.
Fortunately the International Body for Water Quality has initiated plans to phase out nonyl phenol by the year 2,000. But nonyl phenol and kelthane are by no means the only estrogen-like chemicals. According to Dr. Theo Colburn: "It isn't just one product that's causing the problem. It's a host of products. It's the construction material that we are using, it's the plastics we're using. It's not only the pesticides and it's not only the chemicals that we've released in the past that we've banned and restricted, but they're still out there. In essence what we have to do now is to make sure that we revisit every piece of legislation that's coming up for reauthorization to make sure that we include not only cancer as a risk element but that we include these transgenerational health effects: the effects on the developing endocrine, immune and nervous system which are all linked."
Chemicals known to disrupt the endocrine system and act as estrogen-like hormones include: DDT and its degradation products, DEHP (di(2- ethylhexyl)phthalate), dicofol, HCB (hexachloro-benzene) kelthane, depone, lindane and other hexachlorocyclohexane congeners, methoxychlor, octachlorostyrene, synthetic pyrethroids, triazine herbicides, EBDC fungicides, certain PCB congeners, 2,3,7,8,-TCDD and other dioxins, 2,3,7,8-TCDF and other furans, cadmium, lead, mercury, tributyltin and other organo-tin compounds, alkyl phenols (non-biodegradable detergents and anti-oxidants present in modified polystyrene and PVCs), styrene dimers and trimers, soy products, and laboratory animal and pet food products. (Reference: Advances in Modern Environmental Toxicology, Vol. 21, Chemically-Induced Alterations in Sexual and Functional Development: The Wildlife/Human Connection, 1992, Princeton Scientific Publishing Co.)
Much of this material was originally broadcast on the BBC "Horizon" TV program in 1993 and rebroadcast in the United States as a BBC/ Discovery production in September 1994. The video copy is available for loan only ($2.90 within U.S., more overseas) from Ellen and Paul Connett, Waste Not, 82 Judson, Canton, New York 13617 U.S.A. Telephone 315- 379-9200, Fax 315-379-0448.