SPERM production, the essence of masculinity and the essential male component for the survival of the human species, is in rapid decline, according to a new study published this month.
The issue of declining sperm count, with its implication for the continued fertility of men, is so hot that the United Nations is holding a special conference in Washington this month to investigate it.
The study quoted in the British Medical Journal says normal sperm production (spermatogenesis) decreased in Finnish men from 56.4 per cent in 1981 to only 26.9 per cent in 1991. That's a deterioration in sperm production by more than half in only a decade.
What's more, there was a dramatic increase - from 8 per cent to as much as 20.1 per cent - in the number of men who had no mature sperm cells (complete spermatogenic arrest) while those with partial spermatogenic arrest increased from less than a third (31.4 per cent) to almost half (48.5 per cent).
The study also found that testicles are decreasing in weight, have become increasingly scarred and had smaller seminiferous tubules (the tubes in the lobes of the testes) than only a decade ago.
The study, by a University of Helsinki team headed by Dr Jarkko Pajarinenwas, was enough to fuel the neuroses of the chirpiest doomsday brigade. It was based on post mortem tests of 528 men aged between 35 and 69, half who died in 1981 and the rest in 1991. But what do other scientists make of it?
Dr Louise Drudy, scientist at the Royal College of Surgeons in Dublin, says: "Although the study shows a difference in spermatogenesis between the two groups of men at necropsy, it does not provide direct clinical evidence that spermatogenesis has deteriorated". In other words, the study on dead, men, suggests sperm count is deteriorating but doesn't prove it.
Prof Lewis Smith, director of the Institute for Environment and Health at Leicester University says that while the study is not conclusive "there's enough evidence to take the issue seriously".
Mr Ted McDermott, Consultant Urologist at the Meath and St James's hospitals in Dublin, is cautious about it. He notes the report says nothing about when they took the biopsies. He believes results could vary depending on how long after death the biopsies took place.
But the report cannot be dismissed. In 1992 the British Medical Journal published a paper reviewing more than 60 scientific papers over 50 years on alleged declining sperm count. It found that sperm count had almost halved from 1940 to 1990. Though some have contested these findings, others have confirmed them.
It also claimed that semen production had fallen, that there was an increase in testicular cancer, and suggested an increase in testicles failing to descend and congenital defects.
So, if it's true that sperm counts are deteriorating, what could be causing it?
The usual suspects fall generally into men's behaviour and environmental factors. Tight under pants, smoking cigarettes, drugs, too much booze or coffee and frequency of ejaculation have been taken in for questioning.
Environmental suspects include toxins, chemicals, industrial solvents and xenoestrogens (oestrogen like substances which mimic female hormones).
Gwynne Lyons, pollution consultant with the Worldwide Fund for Nature, says that higher predators - humans included - are at risk from oestrogen mimicking substances. "If you expose rats to these they decrease their testicle weight and reduce their sperm output."
She says that if seals are fed fish from polluted seas their pup production can decrease. Otters in the polluted Lower Columbia River in the US have smaller penises and testicles than those from non polluted areas. All Florida panthers, she says, now have undescended testicles.
Ms Lyons blames DDT pesticides, PCBs (industrial chemicals), phthalates used to soften plastics and bisphenol A used in polycarbonate plastics and in food tins. She says: "More men are being pushed into the infertility region. Epidemiological studies have shown that men in the 1990s have lower sperm count than before. We ignore these warning signals at our peril. We don't have the luxury of being able to wait for proof."
THE last word goes to a character in P.D. James's novel, The Children of Men, a book inspired by a report of declining sperm production in men: "Of the four billion life forms which have, existed on this planet, three billion, nine hundred and sixty million are now extinct. We don't know why. Some by wanton extinction, some through natural catastrophe, some destroyed by meteorites and asteroids. In the light of these mass extinctions it really does seem unreasonable to suppose that Homo sapiens should be exempt. Our species will have been one of the shortest lived of all, a mere blink, you nay say, in the eye of time."