"See you later, alligator. Here comes the silent spring".
By Eline E. Haenebalcke and John J. Wielgus, Professor of Biology
Rachel Carson’s book of the early 1960’s (Silent Spring) was astounding. It warned of the consequences of the ubiquitous use of the pesticide DDT, predicting that it would linger in the environment, become chemically transformed into innumerable compounds, and have diverse, far-reaching environmental effects. Not only was Carson correct in her environmental assessment, her monumental work stands as one of the factors responsible for the establishment of the Environmental Protection Agency, the Endangered Species List, and a worldwide environmental ethic that we now take for granted. Subsequently DDT was banned, we learned how to respect and protect the environment, and all should now be under control, right? Wrong! Unfortunately, there is mounting evidence that not only is DDT poisoning still with us, but also that many currently used compounds are persisting in the environment as specific biological activators. The growing list of problems includes shrunken alligator penises, decreasing sperm counts in men, altered cancer rates, and other reproductive organ pathologies such as increased cases of endometriosis.
University of Florida wildlife biologist Louis Guillette rang the first alarm bell after several years of studying the alligator population in Florida’s Lake Apopka. It was known that thousands of gallons of DDT-containing pesticide had been spilled into the lake in 1980 and he had expected that this wildlife population would be damaged by the accident and that hunting the reptiles would have to be curtailed. The alligators had other problems besides dodging alligator cowboys, however. Lake Apopka male alligators’ penises were only 25% their normal size and their testosterone levels were so low they were likely to be sterile. It was already known that a major breakdown product of DDT, called DDE, acted in the same manner in some systems as does the female sex steroid estrogen by binding to and activating the estrogen receptor. Spurred by his findings at Lake Apopka, Guillette preformed some scientific detective work and announced to a congressional panel "I think we have a problem here… every man in this room is half the man his grandfather was". Guillette referred to a 1991 Danish study which concluded that since 1938 sperm counts of men in the United States and 20 other countries have declined by an average of 50 percent, enough to threaten the fertility of these men. Was it DDE causing this declining fertility? We now know that there are at least 50 compounds which have "gender bending" hormonal activity and with which we are in frequent contact. The list is astonishing. For example, vinclozin, a fungicide used on fruit, binds to the receptor for testosterone, causing laboratory rats to become hermaphrodites. Dioxin, produced when chlorine-containing compounds are burned, mimics estrogen, as does a common plastic called p-nonylphenol. Polycarbonate, used to make water jugs, leaches out bisphenol-A, another molecule with estrogenic activity. Polycarbonate is also commonly used to make baby bottles, endangering the gender-specific developmental programs being played out in young brains. Polychlorinatedbiphenyls (PCBs), necessary for transformer construction, bind to the receptors for the thyroid hormones, also critical for the development of the neonatal brain. These and other compounds also have the nasty habit of persisting in the environment and working their way into the food chain, ending up in human adipose tissue and, eventually, even in mother’s milk. Most alarmingly, such compounds have been shown to affect mitotic activities of cells, making some tissues more susceptible to the cancer state. For example, prostate cancer is known to be estrogen sensitive and this cancer has risen 126 percent since 1973, according to the National Cancer Institute, even after adjusting for the aging of the population. Women also appear to be at increased environmental risk. Mary Wolff of Mount Sinai School of Medicine reports that unusual amounts of DDE are found in women with breast cancer. In one study women who had the highest DDE levels were four times as likely to develop the disease, when compared to those with lower concentrations.
It should be pointed out that much of the evidence regarding these "hormonal impostors" is still controversial and that cause and effect relationships are established only in a few cases with laboratory animals. Nonetheless, it seems that "silent spring" is still very much with us, and that we must return to the environmental drawing board. Perhaps careful screening of all new chemical products should be required, in a way similar to the registration procedure for pharmaceuticals under the Food and Drug Administration. Or perhaps "environmental impact studies" should be required for all novel chemicals, such as is required by the Environmental Protection Agency for construction on pristine land. Whatever the possible solutions it is clear that there is more than ever a need for environmental vigilance and an acceptance of our very real biological connection with our planet. In other words, it really is proving impossible to live a healthy life on an unhealthy planet. Just ask an alligator.