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偽ホルモンーまとめ この文書は、国立野生生物連盟五大湖情報センター506 E. Liberty St., Ann Arbor, MI 48104, April 4, 1994. (Internet: nwfgrlks@igc.apc.org) 313/769-3351; Fax 313/769-1449の報告書「偽ホルモン」のまとめです。 報告書は＄6.00で入手できます。この報告書は、コピーして配布してもかまいません。 健康の基盤―内分泌、免疫系と神経系の相互作用ーが世界中の環境中で人工化学物質のために脅かされている。 「偽ホルモン」化学物質が日常の環境中で複雑な生命組織を脅かすレベルになっていることを示す証拠が沢山出てきている。 人類の生殖能力、子供達の健康、地球上の生物多様性が危機に直面している。 生殖や内分泌撹乱物質として知られる少なくとも48種類は、アトラジン、エンドサルファンなどの農薬；PCB,ダイオキシン、水銀、カドミウム、ヘキサクロロベンジンなどの工業化学物質；消費財から染み出すプラスチックの成分である。 塩素は、これらの約半分近くに入っている。 This report is about the effects on wildlife and people from environmental exposure to such chemicals. It is intended as a compendium for a general reader with a modest understanding of biology and environmental issues. Its objective is to summarize the latest research and point out emerging trends in sceintific findings, as well as new questions being raised. Our conclusions: Current industry practices and consumer habits pose unacceptable risks to life from exposure to toxic chemicals. Government regulations and industry testing of chemicals provide inadequate protection, particularly from risks of exposure to everyday combinations of environmental contaminants that can damage health. Hormone-like chemicals' effects on life are difficult to predict; absolute cause-and-effect relationships are often impossible to prove. Some of the most disturbing evidence, however, comes from Earth's wild kingdom. Contaminant-related damage to a wide range of wildlife species appears to have common features:
Among the most bizzare trends cited in this report are discoveries of sexual anomalies in wildlife. Various forms of "inter-sex" feature of male/female organs are being seen globally in marine snails, fish, alligators, turtles, fish-eating birds, marine mammals and bears. Just as there are major global health problems in a wide variety of wildlife, we see similar trends in humans. In males, sperm counts are down, genital abnormalities in baby boys are up, cancer of the testicles and prostate gland are up. In females, breast cancer now strikes one in nine, with links to environmental chemicals increasingly implicated as a cause. Endometriosis is increasing; in recent primate studies, this painful disease has been linked to dioxin exposure. In children, problems of hyperactivity and aggressive behavior seem to be increasing and overall school performance seems to be decreasing. Human, wildlife and laboratory animal studies have extablished correlations between maternal exposure to environmental pollutants and these types of problems in offspring. As humans in industrial countries such as the U.S. and Canada, all of us typically carry 30-50 parts per trillion (ppt) of dioxin-like pollutants in our bodies (as measured by "toxic equivalency factors," or TEFs, which add up the dioxin-like toxicity of dioxins, furans and PCBs). This is the same range of exposure believed to be affecting some wildlife populations. Our continuing exposure is in the order of 3-10 picograms per kilogram per day, which translates to about 0.2-0.6 ppt per day for a 140-pound person. However, a nursing infant's daily exposure may be 10-20 times higher than that rate. There are at least five ways that environmental contaminants can disrupt vital functions of the endocrine system, whcih includes the organs that produce hormones that control functions such as metabolism, sexual development and reproduction:
The complexities of potential interactions with normal cell functions are remarkable. Natural hormones and hormone copycats have different effects on different parts of the body; can have different effects at differerent stages of development; can have different effects depending on nutritional health, age, genetic pre-disposition and even time of the year or the day that exposure occurs; can vary in their effects, depending on the presence of other chemicals; and can vary greatly in effects among different species. The way scientists identify chemical compounds and describe their effects can be confusing. Not all toxic chemicals behave as hormone copycats. In addition, some chemicals that act as hormone copycats may also produce cancers or other overt toxic reactions. The ways that hormone copycats can interrupt endocrine and other systems are difficult to decipher and separate, which is not surprising, given the exquisite complexities of and interactions among endocrine, immune and nervous systems. The public must continue to be concerned about environmental pollutants that can be acutely toxic or cause cancer and other diseases; nevertheless, the magnitude of potential impacts of hormone copycats warrants special public attention. Fetuses and newborns are particularly susceptible to hormone copycats. At these stages, the systems that provide protection against foreign chemicals, the liver enzyme system and the blood-brain barrier are not fully developed. Exposure to hormone-like chemicals early in embryonic or fetal life, for example, can lead to the development of major structural changes in the genital tract, including tumors and other abnormal cell growth. Damage done at this stage can be permanent and irreversible. Often, the cause is difficult to determine because the parents may show no obvious adverse effects associated with exposure to hormone copycats, and the damage to the offspring may not reveal itself until maturity. No component of the chain of life is safe -- from minute "water fleas" in backyard ponds to polar bears at the north end of the globe. The table on the next page shows the general trends during the last 50 years in uses of chlorinated organic chemicals and pesticides around the world. Note that peak use appears to have occurred in the 1960's and 1970's, when today's generation of young adults was being born to parents who were exposed as adolescents. The second table summarizes general trends of pollution-related declines and abnormalities in the wildlife kingdom. (NOTE: THE TWO TABLES ARE AVAILABLE IN THE ORIGINAL DOCUMENTS THAT CAN BE ORDERED.) Many of these declines of bird, fish, reptile and mammal populations are correlated to exposures to pollutants capable of disrupting endocrine functions. Chemicals frequently blamed include PCBs, DDT and dioxins. Nevertheless, definitive links between specific chemicals and many wildlife maladies have not been proven because animals are exposed to so many chemicals. For example, alligators in Florida's Lake Apopka don't reproduce well. Males have abnormally small phalluses. Pesticide pollution (DDE and dicofol) is blamed. Around the Great Lakes, bald eagle reproduction is low and an unusual number of baby eagles are born with crossed beaks. The parent eagles' diet of PCB-contaminated fish and birds appears to be the cause. In other cases, combinations of pollutants in the food chain appear responsible. Beluga whales in the St. Lawrence River, swimming in the toxic chemicals discharged from the Great Lakes and from Quebec rivers, are vanishing. They suffer from tumors and a variety of health ailments. And in some cases, the causes are speculative or unknown, such as the wholesale disappearance of frogs and toads in the mountains of the western U.S. since the 1970s. There is recent evidence that pollution-causing thinning of the earth's ozone layer may be a cause. Other scientists suspect that air-borne pollutants, including pesticides that drift from farms, are a factor harming amphibian health, but the truth remains unproven. Slowly, we are awaking from a state of denial. Hormone copycats are ubiquitous in pesticides, building materials, consumer products and environmental pollutants, and largely beyond our individual control. The reality of what is happening in the environment and the personal costs of pollution are dawning on us. These are not someone else's problems. The average man today produces only half as much sperm as his grandfather did. He is far more likely to contract certain cancers, including prostate and testicular cancer. The average woman today is twice as likely to contract breast cancer as her grandmother. What will be the odds of these and other maladies afflicting our grandchildren? The public's concern about cancer has guided policy decisions on pollutants, and to an extent, the resulting regulations have provided some protection from hormonal effects. The regulations are inadequate, however, because impacts on wildlife have been observed at levels of contamination far below those that cause cancer. The hormone-like potency of many of these contaminants is unknown. Some solutions exist today. We recommend in this report that federal environmental and food safety laws be revised to contend with sublethal effects of long-term exposures to combinations of chemicals that impair endocrine, immune and nervous systems. Regional programs, such as the U.S. Environmental Protection Agency's proposed Great Lakes Water Quality Initiative, can help lead the way. A phase-out of most uses of chlorine as an industrial feedstock has been recommended by the U.S.-Canada International Joint Commission in response to these problems. Recently, President Clinton, in his proposal for reauthorization of the Clean Water Act, recommended a study on reducing and eliminating chlorine in several industries. Fundamental changes far beyond anything being seriously contemplated by government regulators are needed in chemical use and management on farms, in industries and in homes. For example, "integrated pest management" is a step toward reducing farmers' reliance on chemical poisons on crops. Bioassay tests that detect hormone-like characters of chemicals must be approved by federal agencies and adopted for everyday regulatory use. Chemicals that fail such bioassays should not be sold or used. We recommend that decisions to phase out ("sunset") individual chemicals and classes of chemicals must be based on the weight-of-evidence, not on a judicial standard of guilt beyond reasonable doubt. The burden of proof must be on chemical makers and users to establish the safety of exposure to mixtures of chemicals in the environment prior to sale and use. Chlorine-based chemicals should be targeted first for sunsetting. Finally, it is up to ordinary people to change public policies regarding chemical use, management and regulation. Not too long ago, for example, the pleasures of smoking were viewed as innocent and a sign of affluence and status. No longer. That same change in our innocence about exposure to endocrine-disrupting chemicals is urgently needed. Unlike tobacco smoke, pollution doesn't always seem to vanish when the smoking stops. It often persists, building up in the environment and our food chain, and affects future generations. We delay change at great peril. Warnings are clear from the wildlife kingdom and from scientists: "... Unless the environmental load of synthetic hormone disruptors is abated and controlled, large scale dysfunction at the population level is possible." (Wingspread Statement, 1991) This Wingspread Statement warning came from a meeting of 21 experts from diverse disciplines from the U.S., Canada and Europe. Included were noted scientists in the fields of toxicology, wildlife population biology, epidemiology, psychiatry, anthropology and cell biology. The Statement was agreed upon by all the scientists present; each month evidence mounts in support of the scientists' unanimous conclusions. A few of the scientists most closely monitoring wide-scale changes in wildlife and humans are starting to sound an alarm. We should listen to them carefully. Dr. Louis J. Guillette, Jr. and his colleagues at the University of Florida, for example, have focused their wildlife toxicology research on alligator and turtle reproductive problems caused by exposure to pesticides. How does Dr. Guillette view the global implications of the emerging research on effects from environmental pollutants? Here's what he recently said on the documentary, Assault on the Male, produced by BBC television and expected to be televised in 1994 by The Discovery Channel: "Imagine if, for the last 50 years, we had sprayed the whole earth with a nerve gas. Would you be upset? Would I be upset? Yes, I think people would be screaming in the streets. Well, we've done that. We've released endocrine disruptors throughout the world that are having fundamental effects on the immune system and on the reproductive system. We have good data that show that wildlife and humans are being affected. Should we be upset? Yes, I think we should be fundamentally upset. I think we should be screaming in the streets." -- Dr. Louis J. Guillette, Jr.; Professor & Scientific Director; Biotechnologies for the Ecological, Evolutionary & Conservation Program; University of Florida - Gainsville. This report was prepared by the National Wildlife Federation's Great Lakes Natural Resource Center (GLNRC). The author is Wayne A. Schmidt, GLNRC Research Specialist. Portions of this report are revised from a previous GLNRC publication: Hormone Copycats: New Pollution Threat to the Great Lakes Environment (Aug.16, 1993), written primarily by Ann Lukens, MPH, formerly a GLNRC intern and graduate of the University of Michigan's School of Public Health. We are indebted to Dr. Theo Colborn, senior scientist with the World Wildlife Fund, for assistance in compiling information used to prepare this report. This report is part of the GLNRC's Great Lakes Water Quality Project. Primary funding is from the Joyce Foundation, with additional support provided by the George Gund Foundation and the C.S. Mott Foundation. The interpretations and conclusions of this report represent the views of the National Wildlife Federation and not necessarily those of any of the contributors, reviewers, funding organizations, their trustees or officers. All information Copyright ｩ1997,1998, 1999,
2000, 2001 PPNF. All rights reserved. page last modified: 01/18/2001 |
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