Chemical Villains: A Case Umproved : Health: A new book blames ‘hormone mimicking’ compounds for a host of societal ills, but its scientific base is shaky.

As a physician, I learned a fundamental rule of medicine: “Do no harm.” But after practicing medicine for 40 years, training medical students for 30 years and serving a four-year term as the nation’s top health official, I would add another guiding principle: “Do not needlessly alarm.”

I believe this second credo should also be the basis for public discussion of the new book “Our Stolen Future,” by zoologists Theo Colborn and John Peterson Myers and journalist Dianne Dumanoski. According to the authors, certain synthetic chemicals are mimicking reproductive hormones and are the catch-all culprit for a host of societal ills that range from allegedly declining sperm counts to increased rates of breast and prostate cancer, gang violence, hyperactivity in children and possibly even lower IQ scores.

But just as physicians must be judicious in explaining the probabilities of various diagnoses to their patients, we would do well to take a moment to sit back and put the book’s claims into perspective.

Taken as a whole, it’s important first to remember that the vast majority of its allegations are unproved--which the authors admit. While a scientific case built on inferences drawn from innuendo, data extrapolations and hypotheses may be sufficient for the authors and their publisher, most physicians, toxicologists and other scientists see a huge difference between theory and convincing evidence.

Nowhere is this discrepancy more apparent than in the book’s contention that sperm counts are declining at such an alarming rate that human males’ ability to reproduce may be in danger of extinction. To the contrary, the totality of scientific research on this issue presents a far different picture. According to a growing number of studies, there has not been a decrease in global sperm count and quality. In fact, since 1970, there may actually have been increases in some places. For real-world verification of these findings, one need only to look to the explosive growth in world population that is adding 90 million people per a year to the planet--most of which is occurring, ironically, in countries that still use some of the chemicals vilified by the book, including DDT.

No one disputes that there are serious global environmental health issues that must be addressed. However, the authors of the book rely on isolated incidents of health effects, particularly in animals, that have resulted from massive doses of chemicals. Through extrapolations and leaps of faith, the authors extend their hypotheses to people in everyday life. Unlike the Lake Apopka alligators the book cites, few people live in a toxic waste site. The extreme examples cited in the book simply do not reflect the infinitesimal background levels of chemicals in daily life.

The authors also fail to mention that hormone-mimickers occur naturally, most notably in fruits and vegetables. According to some scientists, these can be as much as a thousandfold higher than the synthetic chemicals in our diet. A recent report by the National Research Council of the National Academy of Sciences concluded that Americans should be less concerned about pesticide residues and more concerned about eating fewer calories and fats.

The book does not distinguish between the hypothetical risks of synthetic chemical use and the real risks the world would face without them. For example, DDT, one of the leading “chemo-villains” in the book, is still used to control mosquito populations in some parts of the world, where it prevents thousands, perhaps millions, of deaths from malaria every year. With the increasing demands of global population growth, a safe and plentiful food supply would not be possible without crop protection programs that include the use of pesticides. And without plastics, our food, medicines and blood supplies could not be protected and kept sanitary.

Equally troubling from a public health perspective is the book’s failure to establish priorities for dealing with these alleged risks. What would be the consequences of devoting millions of scarce scientific research dollars to investigate the alleged effects of hormone-mimicking chemicals? Would this detract from efforts to find cures for major killers such as heart disease, cancer and AIDS.

Protecting public health can be a difficult balancing act. The key lies in setting responsible priorities so that we can channel resources and energies into efforts that will yield the greatest good for the greatest number.

With reports of potential new health threats surfacing almost daily, how can we as a nation make sure our that public health priorities remain on track?

* By making a commitment to risk assessment that includes an evaluation of hypothetical versus real risks, and costs versus benefits.

* By allocating resources to priorities that will achieve the maximum good for the most people.

* By providing the public with solid, verifiable information that people can use to make personal health decisions for longer and healthier lives.

No one can argue that the book’s theories do not warrant more investigation. Important research is under way by a number of groups, including the National Academy of Sciences. But while we are waiting for the answers, it’s essential that we not be misled by the authors’ good intentions nor needlessly alarmed by their unproved allegations.

Synthetic chemicals may seem like the obvious culprit for some of what ails us, but as a nation we must take care to keep our public and personal health priorities straight, particularly when the full weight of scientific evidence does not support the charges and the real-world risks far outweigh hypothetical ones.