In Harm's Way

Tuesday, March 29, 2011

Risk experts sometimes joke about an apocryphal tourist, lounging on the beach at Lake Michigan, who hears a rumor about a shark sighting and decides to split. He quickly polishes off his six-pack, lights up a cigarette, and, without fastening his seat belt, speeds off in a top-heavy SUV with bald tires while texting his girlfriend.

(There are no sharks in the Great Lakes, by the way.)

Those of us devoted to raising the consciousness of the American public about health and science are clearly failing. How else to explain the plethora of common, serious mistakes of omission and commission? Consider these extraordinarily antisocial or self-destructive examples:

• One-third of mothers answering a recent survey admitted that they did not plan to have their kids vaccinated against the flu. Worse, more than a quarter of health care workers polled also said they intended to avoid the shot.

Such behavior is unwise and irresponsible. Flu not only causes misery and economic losses, but it’s also a killer—of thirty-six thousand in an average year in the United States. The more people who are immunized, the greater the herd immunity, a kind of biological barrier to the spread of the disease.

• An astonishing 40 percent of women who chronically take medicine that is “contraindicated in women who are or may become pregnant”—based on evidence that the risks of birth defects outweigh any potential benefits of the medication—fail to practice birth control as prescribed.

Their drug-refill patterns suggest that their compliance with oral contraception is no better than that of all women eighteen to forty-four years old. They are, therefore, at high risk of having babies with birth defects.

• Women who have a high risk of breast cancer can reduce their risk substantially by taking drugs of two types—selective estrogen receptor modulators and aromatase inhibitors—yet only one-fifth or fewer of eligible women take one of the effective drugs.

• A recent study of 1.6 million women insured by Medco Health Solutions found that on average only about half got an annual mammogram. The frequency was highest for those fifty to sixty-four years old, but still low at an average of 54 percent.

• Hypertension, or high blood pressure, is a common but symptom-free illness that is a major cause of heart attacks, strokes, and kidney disease—yet only 10 percent of patients take their blood-pressure-lowering medication as prescribed for more than one year.

• In addition, asthmatics, diabetics, and even AIDS patients have all been shown to lower the dose or frequency of their therapy, or to skip it altogether.

• Shoveling snow leads to an average of about 11,500 serious injuries and medical emergencies treated in emergency rooms every year, according to a March 2010 study that analyzed data from one hundred hospitals from 1990 to 2006. The most common kinds of injuries were acute musculo-skeletal exertion (53.9 percent), followed by slips and falls (20 percent) and being struck by a snow shovel (15 percent).


While they indulge in such high-risk behavior, many of these people worry about activities or products that pose only de minimis, or negligible, risks. These include contact with minuscule amounts of chemicals that have been in widespread and safe use for decades.

One high-profile target lately has been bisphenol A (BPA), a component of certain plastics. BPA makes products as diverse as electrical boards, contact lenses, water bottles, and cans strong yet flexible and resistant to breakage. Another is chromium-6, which a recent study by an environmental activist group found in the tap water of thirty-one out of thirty-five cities in its nationwide sample. But although such studies—in which one looks for a certain chemical in the air, water, or humans’ bodies—are increasingly common, for various reasons their significance is questionable. First, analytical techniques have become so sensitive that they can detect amazingly minuscule amounts of almost anything. Second, even if a substance is found in our bodies, its mere presence does not mean the substance is harmful. That applies even to chemicals that can be deadly at high levels. Consider botulinum toxin, for example, which in food can cause botulism, a particularly lethal form of food poisoning. In tiny amounts, however, it is a valuable pharmaceutical, used to treat muscle spasms and remove wrinkles. Its brand name is Botox.

How worried should we be about chromium-6? It can be harmful if inhaled, and probably if ingested in large amounts. Water with high concentrations of chromium-6 fed to rodents causes gastrointestinal tumors, indicating that it is a carcinogen—in those species. But rodents are not little humans with tails. Toxicological findings often fail to translate well from one rodent to another, let alone from rodents (which are very prone to certain kinds of cancers) to humans.

It is useful to consider what California regulators have to say about chromium-6. They have proposed a “Public Health Goal” (PHG) for chromium-6 of 0.06 parts per billion (ppb) in water, which is the estimated “one in one million” lifetime cancer risk level. That means “for every million people who drink two liters of water with that level of chromium-6 daily for seventy years, no more than one person would be expected to develop cancer from exposure to chromium-6.” They picked this very conservative, very low level because “the ‘one in one million’ risk level is widely accepted by doctors and scientists as the ‘negligible risk’ standard.”

But you would never know that from the hyperbolic pronouncements of the Environmental Working Group, which inaccurately called the proposed California PHG for chromium-6 a “safe maximum recently proposed by California regulators” and decried the fact that water in twenty-five of the thirty-five cities tested was found to contain higher concentrations. For their own purposes—that is to say, alarmism and fear mongering (and fund-raising)—they completely ignored California regulators’ blunt admonition that “a PHG is not a regulatory standard. It is only one step in the process of developing an enforceable standard that is set by the California Department of Public Health for drinking water that public water systems must meet.”


But let’s put aside for a moment the hand-waving about the distinction between goals and standards and rodents and humans. We have the advantage of data from what amounts to a long-term, real-world experiment in which humans were exposed over a long period to chromium-6 in groundwater. This was in Hinkley, California, where the Pacific Gas & Electric Company was accused of leaking chromium-6 into the town’s groundwater for more than three decades. Eventually, the company paid $333 million in damages to more than six hundred townspeople and pledged to clean up the contamination. The litigation made a celebrity of activist and paralegal Erin Brockovich, whose story was made into a film starring Julia Roberts.

Even if a substance is found in our bodies, its mere presence doesn’t mean the substance is harmful.

But here’s the denouement that both the litigation and the film missed: a California Cancer Registry survey released last year failed to find a disproportionately high number of cancers in Hinkley. To the contrary: from 1996 to 2008, 196 cancers were identified among residents of the census tract that includes Hinkley—more than 10 percent fewer than the 224 cancers that would have been expected, given its demographic characteristics.

Such surveys are probably not highly accurate, but this one does tell us that if chromium-6 in water is a human carcinogen, it’s certainly not a potent one.

The latest flap over exposure to chemicals was precipitated by an article published by an activist professor at the University of California, San Francisco, who used a database developed by a branch of the federal Centers for Disease Control and Prevention. She found, not surprisingly, that “pregnant women in the United States are exposed to multiple chemicals. Further efforts are warranted to understand sources of exposure and implications for policy making.” But she was not able to draw any conclusions about any possible harm that might have occurred because the database was not structured to determine whether the measured levels of a chemical constitute a hazard either individually or cumulatively. (However, the researcher’s conclusory statements to the media seemed clearly to exceed the limitations of her findings.)

A survey last year failed to find a disproportionately high number of cancers in Hinkley, the town made notorious by Erin Brockovich.

As New York Times environmental writer Andrew Revkin observed, the database is “focused on what is detectable in urine and blood samples” and “is aimed at identifying research questions, but not particularly useful in answering them.” The CDC warns that the “National Exposure Report does not provide health or toxicity information, state- or community-specific data, specific product or environmentally related information, or regulatory guidelines or recommendations,” and that “just because we can detect levels of an environmental chemical in a person’s blood or urine does not necessarily mean that the chemical will cause effects or disease.”

But the spin by the researcher and the media on these rather banal findings derived from the database suggested the sky is falling and children are being poisoned in utero. Similarly, chemophobic activists and cynical (or gullible) politicians continue to cite the “proven” dangers of BPA, chromium-6, and a host of other chemicals. News programs are replete with activists’ warnings about one chemical or another. They and their enablers in the media have carried on an aggressive campaign against “toxic chemicals,” aiming their propaganda especially at parents, scaring them about insidious threats to their children’s health.

In the end, we return to the problem that people frequently make unwise choices: eschewing drugs that prevent heart attacks or cancer but exposing their kids to the real dangers of childhood viral and bacterial diseases while “protecting” them from imaginary hobgoblins such as BPA and pesticide residues in foods. Allowable chemical pesticide residues in food are extremely low—and seldom exceeded—and 99.99 percent of pesticidal substances in food occur naturally.

Scientists, educators, and government officials must work harder to disabuse the public of misconceptions about risk so they can make better-informed, smarter decisions about their health and well-being.