America to test suspect chemicals

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THE POSSIBILITY that human exposure to "feminising" chemicals may be responsible for the startling decline in sperm counts is to be subjected to the world's most extensive programme of research.

The United States Environmental Protection Agency (EPA) yesterday published its plans to screen up to 87,000 man-made chemicals in the environment for their ability to mimic the feminising effects of the female hormone oestrogen.

By next spring, the EPA hopes to begin analysing the first 15,000 chemicals on its list with a highly automated battery of tests that will identify those substances that can act like oestrogen and so disrupt the male reproductive system.

Several studies have now confirmed that sperm counts have fallen significantly over the past half century. The first indications came in a study published in 1992 by Danish scientists, which indicated that sperm counts had fallen by about 50 per cent over a 50-year period.

Further research, some of which was established to try to discredit the Danish findings, supported the general conclusion that the quality and quantity of sperm produced by young men were significantly inferior to that produced by men a generation or more ago.

Other research has shown a rise in the incidence of breast cancer and male reproductive disorders that could also be influenced by exposure to environmental oestrogens. A study published yesterday showed that testicular cancer in men between the ages of 20 and 50 has increased by 80 per cent since the Seventies, which some scientists have attributed to exposure to oestrogenic chemicals.

The EPA will begin testing chemicals using in-vitro tests, which are based on inserting the human gene for the oestrogen receptor molecule into a microbe that will emit pulses of light when a chemical binds to it. Further research on animals will then be used to determine the potency of these oestrogenic chemicals in vivo, which more accurately reflects their effects on humans.

The EPA has decided to concentrate on six types of chemical: contaminants in human breast milk, oestrogen-like substances in soya milk, chemicals in waste sites, pesticides, disinfectants and petrol.