Evidence mounts that pollution hurts reproduction

By Kaoruko Sunazawa Copyright 1998 Asahi News Service December 14, 1998

Evidence is mounting that environmental estrogens are interfering with reproduction in humans, a symposium on the health effects of hormone disrupting chemicals heard on Dec. 11.

Speaking at the three-day International Symposium on Environmental Endocrine Disrupters 98 which opened on Dec. 11 in Kyoto, two researchers presented compelling studies suggesting a link between chemical pollution and lower sperm counts and smaller testes even it has yet to be scientifically proven.

"What we can say at this point is at least something wrong is going on causing testis to become smaller," said Kyoto University Associate Professor Chisato Mori.

In separate presentations, Mori, a toxicology expert, and Shanna H. Swan, a research professor at the University of Missouri-Columbia's Department of Family and Community Medicine, reported finding problems with male reproductive systems in Japan, Europe and the United States arising over the last several decades.

More than 1,000 researchers and officials from government and industry from around the world are attending the conference to discuss and share latest findings about a group of chemicals suspected of disrupting animal including human hormone systems.

The symposium, sponsored by Japan's Environment Agency, is intended to complement the first presentation by the Japan Society of Endocrine Disrupters Research, which has displays outlining 100 recent related research results on exhibit at the Kyoto International Conference Hall.

In her presentation to the symposium, Swan said she reviewed 101 sperm count studies conducted between 1934 and 1996 and concluded that sperm density and counts in the United States and Europe appear to have declined.

She cautioned against making a direct connection to environmental estrogens, however, saying she had not ruled out other causes for the phenomenon.

"Linking the decline in sperm density to environmental factors may be premature," Swan said.

More needs to be done to find the irrefutable evidence of the adverse health effects caused by the chemicals, she said.

That, Swan said, is the reasoning behind a joint international project now under way in Japan, Denmark, France, Finland, Scotland and parts of the United States. The collaborative International Study of Semen Quality in Partners of Pregnant Women uses a uniform standard in selecting its test couples and in the style of questionnaires to make research comparisons easier.

The project is expected to monitor sperm counts and will also collect serum samples from men which will be sent to a Danish institute and kept for a long-term studies. The couples selected for the project will also be surveyed in the future, Swan explained.

Meanwhile, Kyoto University's Mori told the forum that autopsies conducted on about 10,000 Japanese men since 1948 show that the weight of testes compared to the body size has declined significantly over the last half century.

Mori said the men's medical records showed that the average heights, which were 157.66 centimeters in 1948, have grown to 165.07 centimeters as of last year. Weight has increased to an average of 57.03 kilograms from 47.8 kilograms 50 years ago.

But, said Mori, the weight of testes in the men in their 20s peaked in the 1980s at 21 grams and has continued to decline since. No other organ in the bodies of the men showed a similar a reduction, he said.

Like Swan, the researcher was cautious about pinpointing endocrine disrupters as the culprit.

Mori also said his studies have found that it took about 10 to 15 years for men born in the 1930s and 1940s to lose 10 percent of their testes weight. In Men born in the 1960s and 1970s, on the other hand, the peak weight of testes lasts only about five years.

Mori said he suspects the speed of maturity of the testes has increased and said it could be linked with women's accelerated puberty.

Discussions were to continue through the weekend exploring the consequences of exposure to suspected endocrine disrupters on the health and reproductive success of wildlife.

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