Endocrine-disrupting chemicals have become a topic of public concern because they could potentially cause cancer and male infertility. But evidence for a human health problem is hard to find
Endocrine disruptors—or 'gender benders' as they are often referred to by the public—have become the focus of environmentalists and public health advocates who decry a slow poisoning of humans and the environment by the chemical and consumer goods industries. The term is a rather broad label for substances that are able to interfere with hormone receptors or hormonal pathways in the cell. Endocrine disruptors have caused serious public concern, because their interaction with the hormone system could potentially wreak havoc with prenatal and early development and affect a wide variety of organs. Theo Colborn, a researcher for the World Wildlife Fund, painted a bleak picture of their effects at a 2001 meeting of the US Department of the Interior: "... these chemicals can undermine the development of the brain, and intelligence and behaviour, and the endocrine, immune and reproductive systems. ... there is now a growing collection of studies revealing that some of these chemicals can affect our children's ability to learn, to socially integrate, to fend off disease and to reproduce" (Colborn, 2001).
However, as public fear mounted, the evidence for a creeping epidemic caused by endocrine disruptors in the environment remained elusive
In fact, early observations on wild and laboratory animals showed that some compounds that are able to interact with receptor molecules, in particular with the oestrogen receptor, exert effects on the reproductive system of these animals. These observations were accompanied by reports on the increasing incidence of breast and prostate cancer and declining male fertility, and it was only a matter of time before the press took up the issue and parents became concerned about this slow poisoning of their children. However, as public fear mounted, the evidence for a creeping epidemic caused by endocrine disruptors in the environment remained elusive. Although most scientists now acknowledge that many substances can have an effect on the human endocrine system, more recent analysis has shown that many of the claims about health effects were either exaggerated or based on flawed analysis of observations. As Stephen H. Safe, Professor of Veterinary Physiology and Pharmacology and of Biochemistry and Biophysics at Texas A&M University (College Station, TX, USA) put it: "The hypothesis is okay, but we don't even have a problem."
The scientific chapter of the endocrine disruptor story began in the early 1990s with a 'hypothesis' article in The Lancet in which Richard M. Sharpe from the MRC Reproductive Unit at the University of Edinburgh, UK, and Niels E. Skakkebaek from the Department of Growth and Reproduction at the University of Copenhagen, Denmark, wrote, "exposure to exogenous oestrogens, ... during foetal and neonatal life can lead to an increase in reproductive disorders" (Sharpe & Skakkebaek, 1993). On the basis of a meta-analysis of more than 60 studies published between 1940 and 1990, they suggested that abnormalities in the development of male sex organs and a 50% decline in sperm count could be attributed to exposure to oestrogens in utero. The finding that the prescription of an artificial oestrogen, diethylstilboestrol, for pregnant women from the 1940s to the 1970s had caused an increased rate of cervical cancer among the daughters of these women further supported Sharpe and Skakkebaek's hypothesis, and the fear that men could also be affected did not seem so far-fetched.
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