The health-scare headline of the week: "Americans found to have twice as much bisphenol A in their bodies as Canadians."
BPA, as it is known, is a widely used chemical found in baby bottles, containers, CDs, car dashboards, and even dental sealants. A new survey finds that Canadians on average have about 1 part per billion of BPA in their urine, while Americans have twice that amount.
"That's bad news for Americans," observes Mother Nature Network News. "Scientists are worried about BPA," writes the Toronto Globe and Mail.
But most scientists are not worried and do not see this survey as bad news. In fact, it's not news at all. The hundreds of media outlets that ran with this story failed to mention that regulatory scientists throughout the world have uniformly concluded that these levels of BPA are so miniscule as to be basically harmless. "Finding a measurable amount of bisphenol A in the urine does not mean that [it] causes an adverse health effect," the Centers for Disease Control and Prevention reported recently, noting that it is found in more than 90 percent of Americans but is "excreted in the urine within 24 hours with no evidence of accumulation."
When it comes to stories on so-called toxic substances, the public discourse seems infected by a malady worse than microscopic residues: chemophobia. Webster's defines chemophobia as the irrational belief that "chemicals" are bad and "natural" things are good.
In fact, labeling a chemical "toxic" or a "contaminant" is meaningless. Toxicity is a question of degree; exposure is different from effect. Apples, bananas, basil, broccoli, cabbage, citrus fruits, mushrooms, turnips, and many more foods contain naturally occurring chemicals that are toxic--they cause cancer at large lifelong doses in laboratory rodents. Tofu is more estrogenic than BPA.
The chemophobic narrative derives from the precautionary principle--the notion, popular in Europe, that a substance can be banned if it is potentially harmful, even absent hard data demonstrating a cause-and-effect relationship. This is not a scientific standard. In its most extreme applications, tradeoffs are not considered, such as the harm that might be caused from restricting a particular technology or the potential danger of substituting an untested substance for a thoroughly evaluated one.
More than anything, this principle gives legislators and politically appointed regulators--some with limited scientific knowledge--the freedom to pick and choose which substances to restrict. And it threatens to replace the risk standard long used in the U.S. and in most of the world.
Risk describes the probability of danger. The key is setting an appropriate threshold. Until now, regulators have been ultra-cautious, especially in America--establishing limits hundreds to thousands of times more restrictive than those suggested by studies on sensitive laboratory animals. But today, scientists can identify a thimble-full of a chemical after it's poured into Lake Erie. Playing on unscientific fears of trace levels of chemicals, activists are putting pressure on regulators to set thresholds even lower--without evidence that current standards are inadequate.
Consider the case of nuts. Many natural fungi produce mycotoxins that affect up to 25 percent of the world's nut supply. One of these, aflatoxin, can be a significant factor in causing cancer, and infects up to 15% of California's almond crop. The most effective and efficient containment strategy is to use insecticides to control insect crop pests, which would otherwise injure the nuts, seeds or grains, thus providing points of entry for the fungal pathogens to infect the mature or harvested crop and produce the toxins. Yet environmental campaigners adamantly oppose that method of control, in effect ignoring a natural toxic chemical while taking an inflexible stand against a synthetic protective chemical. Such trade-offs mean very real risks to consumers, which can result in injury and even serious illness, and some people may die.
They also have launched zealous campaigns against weed killers that are necessary for crops to flourish. For example, the common triazine herbicides, such as simazine and atrazine, have become central targets of anti-chemical campaigners. Yet, as one example, published studies show that legal limit on atrazine exposure has an extraordinary safety cushion--up to 1,000 times or more what advanced scientific studies has determined is safe for humans. But many environmental campaigners, citing controversial and contested studies on amphibians, lobby for a ban of triazines, atrazine in particular.
Agricultural chemicals are among the most scrutinized and regulated of all technologies. In Europe, whose regulations are already more restrictive than those in the U.S., governments are phasing in precautionary criteria that could blacklist 22 chemicals- about 15 percent of the EU pesticide market. Some environmentalists are pressuring U.S. regulators to abandon a risk-based approach for this more politicized European standard. That would be a mistake. The bottom line is that in order to maintain healthy crops, farmers fight a constant battle against insects, fungi, and plant diseases, as well as weeds (which compete with crops for water, nutrients, and light). Advanced chemical technologies have helped to prevent infectious diseases and to enhance crop yields. These are the drivers of the Green Revolution, which has dramatically cut world hunger over the past 60 years.
Scientists at the World Health Organization, whose mandate is to protect the vulnerable, last year rejected calls by activists to ban atrazine. Recognizing its invaluable role in modern agriculture--atrazine significantly increases crop yields and lowers overall use of pesticides--and basing its decision on new health studies, the WHO actually softened its limits. Its new precautionary standard is 100 times more lenient than the EU's, which many consider to be outdated.
The WHO was wise to consider the tradeoffs, because banning effective chemicals always has consequences. Look again to BPA: Among its myriad uses, it can be found in can liners that increase the shelf life of food and prevent botulism, which is a genuine health threat. There are no effective substitutes. Ban BPA, and people will die.
Many activists claim that dental sealants made with BPA can act as a "hormone disruptor." The science says otherwise. According to a 2010 Harvard study, the one-time exposure to BPA that occurs when sealants are put in is only one-fifth to one-half the exposure a child faces daily from environmental sources. The American Dental Association says that "based on current research," it "agrees with the authoritative government agencies that the low-level of BPA exposure that may result from dental sealants and composites poses no known health threat." Bans make sense only if we gain identifiable health or environmental benefits in exchange.
The FDA, under President Obama, has rejected calls to restrict the use of BPA, noting that its benefits outweigh its risks. When asked last year whether it was harmful to pregnant women or children, then-deputy commissioner Dr. Joshua Sharfstein didn't mince words: "If we thought it was unsafe, we would be taking strong regulatory action."
Only a minority of scientists believe that contradictory results from studies on rodents or amphibians justify pulling useful, and in some cases irreplaceable, chemicals from the market. Not one science-based agency in the world has called for a ban of BPA. (It was restricted for some uses in Canada--when bureaucrats overruled Health Canada's science advisory board, which concluded that there was not sufficient evidence to justify a ban.)
Chemicals get a bad rap. It's becoming increasingly difficult for the public to distinguish genuine risks from chemophobia. The breathless media often compound the confusion. With the stakes so high, scientific literacy is no longer a luxury.Jon Entine is a visiting fellow at AEI.