Study after study reveals that sperm counts in men the world over seems to be dropping precipitously. "Somehow, this chance encounter never goes amiss in populous countries. We are prolific breeders. But something is going wrong", says M L Shah, fertility expert based in Baroda, Gujarat, whose private practice has grown five folds in providing childless couples with a child, in the last ten years. "Most of the problem lies with men — specially over stressed executives. Chemical exposures at work could also have a significant role in infertility. Unfortunately we have no data".

The January 1997 edition of the British Medical Journal reported that researchers in Edinburgh, Scotland, found that men born after 1970 had a sperm count 25 per cent lower than those born before 1959–an average decline of 2.1 per cent a year.¹ A 1995 study of Parisians also found a 2.1 per cent annual decline over the past 20 years.² And in the most comprehensive analysis of all, covering nearly 15,000 men from 21 countries, Danish scientists discovered an alarming plunge of nearly 50 per cent in average sperm counts over the past half-century. In 1976 in the town of Seveso in Italy an industrial accident released dioxin into the local population. Since then the fertility rates in the population had fallen, birth defects had increased manifold, and more girls were being born in the population than in other parts of Italy. None of these studies are without their critics, and a handful of others show either no decline or some localised increase.

Not only do sperm counts seem to be dropping, but the quality of sperm — the percentage of healthy, vigorous cells versus malformed, sluggish ones — appears to be in serious decline as well. Doctors have also noted an increase in the incidence of testicular cancer and undescended testicles. Together, these factors add up to a significant drop in male fertility. "In the 1960s," says Mohan Khartare of In-vitro Fertility Research Foundation, Nagpur, "only about 5–10 per cent of the men who came for consultation had a fertility problem. Today that number is up to 50 per cent. This is a cause of grave concern. But an even graver concern is that there is no one finding out the cause of it."

Infertility risk factors

Cigarette smoke Sperm counts of smokers' are on an average 13-17 per cent lower than non-smokers Pesticides Exposure to pesticides results in reduced sperm count and an increase in abnormally shaped sperms Air pollution Men living in industrial and polluted towns have 6 times more abnormal sperm than men living in clean areas Chemicals Sperm count drops in men exposed to chemicals like DDT, PCB's, dioxins and some petroleum by-products Food additives Food additive like monosodium glutamate (MSG) cause infertility in animals Anaesthesia Animals exposed to the anaesthesia —enflurane show 50 per cent higher sperm damage rate than those not exposed to enflurane Occupational exposure Men who work in aircraft industry, textile dyes, plastic industries, welding or handle paint, chemical solvents or even antibiotics are more at risk of having abnormal sperms.

Just what these causes might be is still largely a mystery. Stress, smoking and drug use are all known to be involved. So is the fact that men are having children later in life, when sperm counts naturally fall off, as well as the increase in sexually transmitted diseases. Even the shift in underwear fashion from boxers to briefs has been offered as an explanation (see box: Infertility risk factors).

Another hypothesis states that a wide range of reproduction-related ills may be caused by chemical pollutants in the environment, including dichlorodiphenyltrichloroethane (DDT), polychlorinatedbiphenyls (PCBs), and a number of other synthetic substances. The idea is that exposure to even traces of these chemicals in the womb can interfere with proper development of the reproductive system, leading to serious consequences years or decades later. Male infertility is just one part of the problem, these pollutants may also be responsible for a rise in breast and other cancers in humans, along with aberrant mating behaviour and genital malformations in animals (minuscule penises among pesticide-contaminated Florida alligators, for example). Chemical manufacturers dismiss these speculations, arguing that nobody has come close to showing a cause-and-effect relationship. In fact, the evidence for a chemical-infertility link does remain largely circumstantial.

What scientists do know is that water, air and soil all over the world are tainted with small amounts of many of these chemicals. They know that once the pollutants get inside the body, they can bind with receptors that normally recognise oestrogen and other natural hormones. They know that these hormones are crucial to the development of a normal reproductive system. And they know that at least in laboratory tests on animals — vanishingly small amounts of industrial chemicals, delivered at just the crucial stage of foetal development, can "feminise" a male embryo, producing smaller testicles, low sperm output and a miniaturised or missing penis.

But until 1992 scientists didn’t know of any convincing evidence that men were experiencing reproductive problems on a large scale. Then came the groundbreaking report by a Danish endocrinologist, Niels Skakkebęk of the National University Hospital in Copenhagen. Skakkebęk and his colleagues did what is called a meta-analysis: they combined the results of 61 separate studies of sperm count and quality over the past 50 years in men around the world, and found that the average sperm count had fallen from about 113 million per ml in 1938 to 66 million in 1990.³ After Skakkebęk’s paper appeared it immediately became apparent that environment is sending a very strong signal that something was seriously wrong.

But not everyone accepts the link between environmental oestrogens and reproductive ills. Some researchers have questioned study methods and find them to be speculative. Other researchers have shown that sperm counts in Finland and France have remained the same. What scientists on both sides of the debate can do, is step up the pace of research. If sperm counts are dropping, even in only part of the world, it would be prudent to figure out why. And if they turn out to be declining everywhere, better to know sooner than later. Extrapolating from Skakkebęk’s admittedly controversial data, it’s conceivable that the average man will be infertile within a century. Even if things are only half as grim, it would be bad news indeed for the human race.

No comebacks
Chemicals mimic human hormones (called endocrine disruptor) or disrupt their functioning. Endocrine disruptors can cause an effect using more than one mechanism for example, DDT acts by bypassing receptors to stimulate a complex mixture of cell signalling proteins leading to cell growth and division. DDT also acts as an antagonist at androgen receptors. These influence growth and development of many organs and regulate reproductive processes. Oestrogen is predominantly a female sex hormone but does play a secondary role in the male. When the ratio of oestrogen to testosterone in the male is too high, feminisation occurs. The reverse too occurs though rarely. Oestradiol is the most abundant and potent of the oestrogen hormones in women of reproductive age. Often these hormones interplay changing the probability of safe conception, or a healthy baby. Chemicals that cause this damage can also persist to impair the growth of the foetus or poison the womb, permanently (see box: Sperm speak).