“It looked like a scatter-gram,” said Dolores Lamb, president-elect of the American Society for Reproductive Medicine. “If you followed the linear, downward trajectory that the researchers had drawn through it – it said all men would be infertile by around 2010 … if the line continued.”
Along with a reduction in male fertility, they wrote that the falling counts coincided with a troubling rise in abnormalities of male genitalia – testicular cancer, undescended testicles and misplaced urethras. Together, it looked to them like a collection of new disorders striking males, one they would later call “testicular dysgenesis syndrome.” And the speed of it suggested an environmental culprit.
Bottom of the animal kingdom
In the days before Viagra, when issues around male sexual health were still in the closet, these findings stoked anxieties: Man's fertility had been measured, and he was falling short.
Yet, said Dr. Lamb, a fertility expert at Baylor College of Medicine in Houston, “people had a field day with this graph. Some researchers did their own analysis and said it wasn't a downward trajectory, but a U-shape, that something catastrophic happened to sperm counts in the 1970s – maybe something to do with Saturday Night Fever – and that things were on the upswing.”
Bernard Robaire, a professor of pharmacology and expert in male reproduction at McGill University in Montreal, calls it “the worst statistically analyzed study that I've seen.”
Yet even Dr. Robaire feels that “it was a good thing because it got people talking about men's health.”
And so began a flurry of studies to investigate if human sperm was truly headed for extinction.
For Richard Sharpe, the world's interest in testes could not have come sooner. An expert in male reproductive health at the University of Edinburgh, Dr. Sharpe is troubled by the health of human testes. For the size of them, he says, men don't produce nearly enough sperm, and most of what they do make is useless – only 5 to 15 per cent is viable. For other male animals – “dogs, cats, sheep, mice, rats, cows, rabbits” – the ratio is nine out of 10: “We're in League Division 7, and every other animal is in League 1.”
At the time of the Danish report, he and Dr. Skakkebaek were leading proponents of the idea that overexposure to the female hormone estrogen had put male reproductive health in peril.
The hypothesis suggests that estrogens found in everyday foods such as milk and soy, along with synthetic estrogens in pollutants, were wreaking havoc with male reproductive systems. It seemed to jibe with reports at the time of testicular cancer rising more than two-fold, news of fish (and other wildlife) becoming feminized and vexing reports, one of them from Canada, that the number of male children being born was lagging behind the number of females.
But studies since have not borne out the estrogen threat and most scientists have largely abandoned the idea, Dr. Sharpe included. Neither has research revealed any one environmental contaminant to explain lower sperm counts in the general population. Dr. Sharpe still suspects a combinations of chemicals play a role, but studies have yet to identify them.
Instead, he says, he now feels that the best predictor of a man's reproductive health is what happened with his mother while he was still in her womb.
Geography is destiny
Researchers trying to confirm the falling-sperm-count story were finding different answers all over the map. Numbers looked higher in Finland than Hong Kong, Scotland and parts of Africa. Recent Finnish numbers have fallen, while Sweden's are stable. Counts look good in France, and bad in Thailand. The U.S. tally plots east over west, with sperm counts higher in New York and lower in California.
“There's a difference between countries, there's a difference between men living in different parts of countries. There is just so much variation,” Dr. Jarvi says. But he says no one can explain if it reflects differences in geography, temperatures, environment or genetics.
What's more, with all the things that can foul up sperm counts, experts say most studies to date are unreliable, including the Danish report that raised the flag in the first place.
Follow us on Twitter: