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. Last Updated: 07/27/2016

Scientists Fear Pollution Can Lower Sperm Count

LONDON -- Men will start becoming sterile by the middle of next century if their sperm count keeps falling at the high rate reported in a new British research paper, the researchers say.

Based on a study by the government-funded Medical Research Council of 577 men in Scotland, it said those born after 1970 were found to have a sperm count on average 24 percent lower than those born 12 years earlier.

The study was published in Saturday's issue of the British Medical Journal, advance copies of which were available Friday.

Dr. Stewart Irvine of the council's reproductive biology unit in Edinburgh who headed the research program in the Scottish capital said the sperm count levels found in the study are not yet low enough to affect fertility.

"There is as yet no evidence that male fertility is declining but the absence of evidence is not evidence of absence. It may or may not be," he wrote.

But he said if the fall continues at the rate noted in the Edinburgh study, men could start becoming sterile by the mid-21st century. "Clearly if the trend were to continue in the same way, the population would be compromised," he wrote.

He added in a BBC radio interview Friday: "If the downward trend continues at the rate it is going at the moment -- and that's a big if -- then one would expect that boys being born in the middle of the next century might be running into problems,"

Recent studies in the United States, Europe and elsewhere have also shown a fall in the sperm count. The cause of the fall is still disputed but researchers say environmental estrogens are a prime suspect. These are chemicals that mimic the female sex hormone estrogen and are found in substances ranging from detergents to plastic wrappers.

The BBC quoted Dr. Charles Tyler, a researcher at Britain's Brunel University studying the effect of estrogens in the environment on trout as saying when the fish were exposed to them they became practically hermaphroditic.

Tyler told the BBC in an interview: "There is very strong evidence now to show that there are chemicals out in the environment which can affect sexual development."

A French study published last year in the New England Journal of Medicine found that sperm counts of donors at a Paris sperm bank had dropped by one-third over the previous two decades. That study was conducted by Dr. Jacques Auger and others from Cochin Hospital Group in Paris.

The French researchers raised a variety of possible explanations, including male fetuses' exposure to estrogen in the womb as well as environmental pollution and unspecified changes in diet and lifestyles.

Many factors can affect sperm counts, including the way the counting is done, the time since last ejaculation and the donor's age. Men's sperm counts are higher if they have not ejaculated recently, and they go down as they get older.