The Male Fertility Crisis

By Michael Castleman
Published on September 1, 1983
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Illustration by Fotolia/credon2012
Falling sperm counts signal a male fertility crisis.

The effect seems clear: The average sperm count of American males is dropping, and with it male fertility. Studies have indicated that the proportion of men who have 100 million sperm per milliliter (ml) of semen has dropped from 80% in 1929 to 44% in 1950,and all the way down to 22% in 1977! But what is the cause of this problem? Well, for a while, much of the popular news media offered lighthearted speculation that the lowered sperm counts might be related to a society-wide increase in sexual activity (which supposedly left males with depleted reserves) or to widespread use of tight-fitting underwear (which may, indeed, subject heat-sensitive sperm to injurious temperatures by holding them unnaturally close to the body). Nobody thought it amounted to a fertility crisis.

In September of 1979, though, the topic suddenly became less than funny when Robert C. Dougherty suggestedin Chemical and Engineering News that toxic chemicals, not sex or underwear, were the main causes of the decrease in sperm counts. The Florida State University professor found high levels of four toxins in semen samples taken from 132 student volunteers. Three of the seminal pollutants—polychlorinated biphenyls (PCBs), DDT, and hexachlorobenzene—are widely recognized as carcinogens and teratogen’s (substances that cause birth defects by mutating DNA in reproductive cells). The fourth, the wood preservative pentachlorophenol, is quite possibly carcinogenic as well. The students’ most frequent sperm count was 20 million per milliliter of semen. This is an ominously low figure. (Compare it to the 60 million/ml sperm count most prevalent in a 1974 study and 100 million/ml found in 1929!) In fact, a sperm count below 20 million/ml generally indicates a man with a fertility problem. The FSU chemist even said that 23% of the young adults he examined had counts so low that he considered them almost certainly sterile.

Very Vulnerable

Dougherty noted that his findings were suggestive, not definitive. However, since 1775, when Percival Pott reported unexpectedly high rates of scrotal cancer in British chimney sweeps, and soot became the first identified environmental carcinogen, it’s been recognized that the testicles are particularly sensitive to toxic substances. And small wonder: Those reproductive organs contain the body’s highest concentration of genetic material, and this DNA — housed in cells so fragile that millions of them are needed to provide a reasonable chance that one willfertilize an egg — is poorly protected from chemical attack. In addition, carcinogens tend to cause tumors most quickly in tissues composed of rapidly dividing cells — and the cells that cleave the most in adult men are those involved in spermatogenesis. Indeed, the testicles are so sensitive to toxins that Dr. Charming Meyer, chief of the Hazards Branch of the National Institute of Occupational Safety and Health, has suggested that regular employee sperm counts be used to test the safety of industrial chemicals!

Other Culprits

In two regrettable extreme instances, Dr. Meyer’s suggestion has, in effect, been followed. The instances occurred when a pair of chlorinated hydrocarbon pesticides were involved in infertility scandals. Kepone, the first, apparently caused worker sterility at its production plant — Life Sciences Products Company — in Hopewell, Virginia. It was also discharged into the Chesapeake Bay, where it turned up in commercial fish in concentrations high enough to “seriously jeopardize” the local fishing industry, according to the American Journal of Epidemiology. Likewise, workers in Occidental Petroleum’s Lathorp, California plant noticed that men who worked with the pesticide dibromochloropropane (DBCP) became ill and seemed unable to father children. After tests showed that the workers were sterile, California banned DBCP in 1977. Yet the pesticide continued to be used extensively in other states, leaving detectable residues on a variety of fruit crops. In 1979 the Environmental Protection Agency banned its use nationwide, on all crops except pineapples (where it supposedly leaves no residue).

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