HUGE DROP IN SPERM COUNTS REPORTED.

Byline: Brigid Schulte Knight-Ridder Tribune News Wire

After years of conflicting studies and disputes about whether human sperm counts are decreasing, a definitive report says the verdict is clear: Sperm counts in the United States and Europe have dropped enormously in the last 60 years.

The report found that sperm counts in the United States have fallen an average of 1.5 percent per year since the 1930s, a far sharper decline than earlier studies have found. The drop in Europe is twice as steep. Results were inconclusive for Asia, South America and the rest of the world.

``My hope is, this study will change the question of concern from if there is a decline, to why there is a decline,'' said Dr. Shanna Swan, chief of the reproductive epidemiology section at the California Department of Health and the principal author of the report. ``I think it's time we looked at that.''

The study is in today's issue of a journal published by the National Institutes of Health, the federal government's prestigious medical research agency.

Falling sperm counts in the last half century, Swan said, are associated with higher rates of certain types of cancers of the male reproductive system and a growing number of unusual birth defects. Fertility rates in the United States, although declining, have not yet been associated with the lower sperm counts.

No one knows what is causing the decline, but studies on lab animals suggest that low sperm counts and reproductive problems may stem from being exposed to certain chemicals while in the womb.

``Is the sky falling in? I don't think so. Even though sperm counts have declined, even gone down to about 60 million sperm per milliliter, it's still 60 million. You only need one to make a baby,'' she said. ``But it is a red flag for increasing problems we see in other areas.''

For those with low sperm counts to begin with, Swan said, the falling sperm count could play a role in making them infertile.

Swan, who serves on the National Academy of Science's panel looking into hormonally active agents in the environment, is publishing her report in Environmental Health Perspectives, a monthly health journal of the National Institute of Environmental Health Sciences, a branch of NIH.

The controversy Swan attempts to put to rest started in 1992, when a group of European scientists looked at 61 studies and asserted that from 1938 to 1990 sperm counts around the world dropped from 113 million sperm per milliliter - about 18 droplets from an eyedropper - to 66 million sperm per milliliter, a decline of about 1 percent per year.

But just as soon as the study was published, critics attacked, blasting the way the study was done and asserting that sperm counts had not declined. Other studies emerged, with contradictory conclusions. In Seattle, for instance, researchers found no drops in sperm count. In New York, they found slight increases over the years. And in Paris and Denmark, researchers found precipitous declines.

The argument about what was really happening raged on.

``The main problem that has gotten in the way of really focusing on how to deal with this decline is arguments about methodology and how you analyze the data,'' said Dr. C. Alvin Paulsen, author of the Seattle report. ``That has sort of blinded people's vision.''

So Swan went back to the 1992 study and, taking the criticism into account, reanalyzed it.

``When I first looked at it, I was actually skeptical. It had been so widely criticized, and I thought it was probably too simple,'' Swan said. ``If the criticisms were correct, the decline would flatten out. So I was extremely surprised that, rather than going away, the decline got stronger in the U.S. and Europe.''

While the report deals with averages and global trends, Swan is the first to admit that geography may play a far more important role. Sperm counts may be falling in one area or in one country and constant or rising in another. The important thing now, she said, is to find out where and why.

Paulsen agreed.

``There's definitive evidence that sperm counts are falling in certain areas of the world, but it isn't uniform,'' he said. ``But something is going on. The most compelling data resides in fish that throughout their lives live in water and are exposed to contaminants.''

Several wildlife studies have found that, in waters contaminated with hormone-disrupting plastics, PCBs or other chemicals, some male fish do not develop proper genitalia.

Sperm counts, studies show, are falling in Denmark, but holding constant in Finland. Denmark, too, is showing higher rates of testicular cancer and certain hormone-related birth defects. One study in London showed falling sperm counts in one water district, one high in metabolites found in oral contraceptives, and constant sperm patterns in other water districts.

Similarly, the Centers for Disease Control report testicular cancers, prostate and breast cancers are on the rise in the United States.