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.
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!
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).
Still, the DBCP that had already been applied didn't go away. Instead, two years after California declared its ban, the persistent hydrocarbon turned up in 100 wells that supply drinking water to area farm communities. As a result, some state officials have suggested that all contaminated wells be plugged; others feel such action would be impractical. At this point, then, nothing has been done about the situation, so DBCP-contaminated water continues to flow into thousands of San Joaquin Valley homes and into irrigation systems that supply water to the nation's leading vegetable-growing region.
Another infamous man-made chemical is dioxin. This potent herbicide — best known as an ingredient in Agent Orange — is one of the most toxic substances on earth. (It causes severe reproductive deformities in monkeys at concentrations of 50 parts per trillion!) Dioxin may or may not reduce the quantity of sperm production, but it clearly seems to have an effect on its quality. Over a million American soldiers are estimated to have been exposed to the herbicide during the Vietnam War, and their children have shown an unexpectedly high rate of birth defects.
Nor is that Asian country the only place that this particular toxin has been used. The chemical 2,4,5-T, which contains 500,000 parts per trillion of dioxin, wassprayed on national forests and highways, power lines, and railroad rights-of-way across the U.S. for years. In fact, seven million pounds of 2,4,5-T was used for such purposes annually until the EPA responded to evidence that the herbicide has caused abnormally high rates of miscarriage and fetal death among women who lived near sprayed areas. [EDITOR'S NOTE: See our interview Bonnie Hill: Oregon Environmental Activist for a full report on that topic.] And even today the EPA permits spraying of two million pounds of 2,4,5-T a year on range- and rice lands.
Worse still, the catalog of genotoxins—substances that cause sterility, sperm abnormalities, or testicular cancer — includes far more than chemical pesticides and herbicides. Another guilty substance is plutonium. Not only is it one of the most potent carcinogens on earth, it appears to accumulate in the testicles (in much the same way, for instance, that radioactive iodine collects in the thyroid gland). Before 1945, no trace of this manmade element existed on earth, but aboveground atomic weapons tests have dispersed an estimated 10,000 pounds of the radioactive genotoxin into the atmosphere. It is believed that all people on earth today carry detectable levels of plutonium in their bodies. In 1980 Dr. Carl Johnson, an epidemiologist at the University of Colorado Medical School, released results of a survey of cancer rates around the Rocky Flats nuclear weapons plant (a facility which has recorded many routine, and accidental, airborne plutonium releases in the last 25 years). Using National Cancer Institute data, Johnson found that overall cancer rates were 24% higher in men living downwind from the plant than in those living upwind. And the most striking difference concerned testicular cancer: The men living upwind had 17 cases of this disease, while those living downwind had 401.
Then again, there's the much less well known genotoxin DES (diethylstilbestrol), the synthetic estrogen that has caused vaginal cancer in some women whose mothers took the hormone while pregnant. A couple of years ago, this drug was linked to testicular cancer in DES sons. A scientist at Memorial Sloan-Kettering Cancer Center in New York found that 10% of that institute's testicular cancer patients had documented histories of DES exposure (a rate three times that which could normally be expected). DES sons also showed elevated rates of sperm abnormalities, infertility, and undescended testicles. Nor are DES users and their offspring the only people who have been exposed to this synthetic estrogen. It was routinely added to about 80% of the animal feed produced in the U.S. from the 1950's until the U.S. Food and Drug Administration banned its use early in 1980, because residues were being found in a variety of meats.
DES is much less commonly recommended for pregnant women, but 10% of all American women still take phenobarbitalduring pregnancy, to combat nausea. (During the 1960's and 70's, 25% of our nation's expectant mothers used the drug.) Yet Dr. Sumner Yaffeof Bethesda, Maryland's Center for Research for Mothers and Childrenfound that when pregnant rats were given the anticonvulsant, only 60% of their male offspring and just 40% of the female ones were able to sire or bear normal babies! Many antibiotics, among them penicillin and tetracycline, also suppress sperm production. Yet according to a 1974 report in the American Journal of Urology this effect is "seldom discussed" in the medical literature. And as DES once was, antibiotics today are fed in large quantities to the vast majority of feedlot-fattened livestock. In fact, in April 1981 the General Accounting Office reported that 14% of commercially sold meat and poultry is contaminated with illegal antibiotic residues and/or unhealthful hormones (such as anabolic steroids).
The list of genotoxins goes on and on. The element lead — like plutonium—accumulates in the testicles, causing genetic damage to sperm by disrupting the zinc metabolism necessary for normal spermatogenesis.
And although cigarette advertising associates tobacco smoking with virility, a growing body of research supports the opposite: that smoking reduces sperm counts. Heavy use of marijuana has also been linked to similar effects. Even regular intake of caffeine may have sperm- and offspring-damaging impact!
During the 1950's, doctors said that 10% of U.S. couples were infertile, and that organic problems in the male partners accounted for only 10% of those problems. Today, a sixth — over 15%—of our nation's married couples are reportedly infertile, and male dysfunctions are said to account for 30 to 40% of the difficulties. (However, since infertility has traditionally been blamed on women, this increased observance of male dysfunction in couples could reflect a belated recognition of long-ignored facts as well as a new biological trend.)
There is also some evidence suggesting that men with low sperm counts are more likely to produce offspring with birth defects. Erik Jansson, an environmentalist with Friends of the Earth (who's working on anti-birth-defect legislation), notes that artificial insemination of women with frozen sperm from third-party donors results in a birth defect rate of 1% or less — in sharp contrast to the overall American birth defect rate of 4.5 to 6%. Jansson states that "the most important reason for the dramatic fall in birth defects with third-party donors of sperm is that the artificial insemination laboratories accept only men with high sperm counts." (The FOE staffer has also concluded that the same findings "suggest that American men are presently responsible for between 78 and 83% of all birth defects in the United States"!)
In addition, testicular cancer rates have doubled in whites and tripled in blacks since 1950, according to the National Cancer Institute. Furthermore, the disease has been striking men earlier in life. A century ago, most victims were fairly elderly, men. By the late 1950's, however, men under 25 accounted for 12% of the cases; today, such young adults constitute 25% of the victims! In fact, although testicular cancer accounts for only %1 of all cancers in men, it has become the most common solid tumor in males aged 15 to 34.
The Thread Of Life
Every man alive today is being exposed to pollutants that are known to diminish his reproductive capacity. And the number of involuntary "chemical vasectomies" (and other male reproductive disorders) clearly seems to be on the rise. So the conclusion is all too plain: Unless reproductively toxic substances are removed from the environment, many people now in infancy may encounter substantial difficulty in obeying one of their most fundamental biological injunctions: to be fruitful and multiply.
EDITOR'S NOTE: Michael Castleman is managing editor of
Medical Self-Care. MSC's Spring 1983 issue focused on men’s health, and included a resource-filled article providing help for couples coping with infertility problems.
On the political side, Friends of the Earth has organized a coalition that's currently proposing federal legislation to help prevent birth defects.This bill would include measures to reduce the exposure of men to toxic substances.