SPERM DECLINE PLAYED DOWN.

Reports of human ‘extinction’ may be exaggerated

Plummeting sperm counts could spell the extinction of the human species? Um, not quite.

Stories this week about a study reporting sperm counts among Western men have fallen by more than half in less than 40 years had researchers warning of a fertility “crisis” and others offering tips on how men could counteract the “shocking” and “all-time low” sperm slump by, among other things, eating tomatoes and pomegranates.

However, a Canadian expert in human sperm pathophysiology says semen analysis tests are among the most poorly performed medical laboratory tests on the planet, with a margin of error as high as 50 per cent.

Yes, all sorts of “nasty” things in the environment are undoubtedly affecting male fertility, says Vancouver’s David Mortimer, president and co-owner of Oozoa Biomedical, an international consulting company in reproductive biology. But it’s not necessarily time to get our shorts in a twist.

The new study, appearing this week in the journal Human Reproduction Update, is billed as the first systematic review and meta-analysis of trends in sperm counts.

Researchers from the Hebrew University-Hadassah Braun School of Public Health and Community Medicine and the Icahn School of Medicine at Mount Sinai, New York, analyzed 185 studies involving nearly 43,000 men from six continents and 50 countries who provided semen samples from 1973 to 2011.

Overall, they found a 52.4-per-cent drop in sperm concentration, and a 59.3-per-cent decline in total sperm count among men from Western countries (North America, Europe, Australia and New Zealand), with no sign of a levelling-off in recent years.

No significant declines were found in men from South America, Asia and Africa, where few studies were published before 1985.

The fall-off in Western sperm counts has implications beyond fertility and human reproduction, the authors warned, citing recent studies linking lower sperm counts with an increased risk of diabetes, heart disease and premature death.

Co-lead author Dr. Shanna Swan, of the department of environmental medicine and public health at Mount Sinai, said the team decided not to throw men with known good sperm counts (those who had fathered a child) into the mix with men who had never tried to get a woman pregnant.

Instead, they separated out the fertile from males whose fertility status was unknown (so-called “unselected” men, mainly college students or men being screened for the military in Europe.)

In the unselected men from Western countries there was a more than 50-per-cent decline in sperm count over the 39 years of the study, from 99 million sperm per millilitres of semen to 47.1 million/ml.

However, while the average sperm count for all men dropped from 92.8 million/ ml, to 66.4 million/ml, that’s still considered within the “normal” range needed to conceive, the NHS Choices reported.

In addition, the researchers analyzed sperm counts but not sperm motility and morphology, partly because that information was missing in older studies.

Still, Swan believes declining semen quality is a signal “something very wrong” is happening at a very basic level in male development, including prenatal exposure to phthalates, a group of hormone-disrupting chemicals most recently found in the cheesy powder in boxed mac ’n’ cheeses. According to Swan, phthalates have been known to decrease testosterone in early fetal life at the time the genitals are forming.

Her co-author Dr. Hagai Levine went further, telling the BBC falling sperm counts may foretell “the extinction of the human species.”

That’s a tad premature, others argue. Mortimer, a past president of the Canadian Fertility and Andrology Society, said sperm motility and morphology are far more important parameters.

“Am I concerned there are things in the environment affecting male fertility? Absolutely,” Mortimer said.

“Does a 50-per-cent decrease change fertility? Not enormously,” he said, adding that a far more significant factor in declining fertility rates is women waiting longer to have babies.

Mortimer also cautioned that studies linking low sperm counts with an increased risk of early death don’t prove cause-and-effect, just an association.