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Benign Study, Toxic Spin
By Steven Milloy Get ready for another round of the supposed horrors done to hormonal systems by so-called “endocrine disrupters” — manmade chemicals in food, consumer products and the environment alleged to cause everything from cancer to reproductive and developmental problems to attention deficit disorder. Though the news essentially is benign, its spin will be toxic. EDs grabbed the media spotlight with the March 1996 book “Our Stolen Future,” an alarmist’s compendium of wild anecdotes. Without a scientific basis, for example, the authors blamed EDs for the phenomenon of “gay gulls”— female herring gulls that nested together because male gulls, supposedly feminized by chemicals, weren’t interested in mating. “Our Stolen Future” was sponsored, authored and promoted by no-holds-barred environmental activists. Much to their chagrin, however, the hoopla over the book faded in the face of unusually balanced media reports featuring criticism of the book and it theories by respected scientists. The scare returned with a vengeance in June 1996 when researchers from Tulane University reported in Science magazine that combinations of pesticides and PCBs were 1,500 times more potent as EDs than the individual chemicals. In study’s wake, a federal law was hastily enacted requiring the Environmental Protection Agency to test chemicals for their ED potential. Within six months, though, scientists from around the world reported the Tulane results couldn’t be duplicated — unusual for a laboratory study. The Tulane researchers subsequently retracted their study from publication. Incredibly, though the study was gone, the requirement for the EPA testing program stayed. During 1997-1999, the ED scare emerged in different forms. Alarmists targeted soft plastic toys, vinyl intravenous bags, baby bottles, and plastic food wrap as consumer exposures to potential EDs. Toy makers reformulated products even though no scientific data showed any cause for alarm. During the controversy, the National Academy of Sciences’ research arm, the National Research Council, reviewed the science on EDs. In August 1999, the NRC reported no persuasive evidence supported the ED theory. The NRC acknowledged that high-level exposures to some chemicals may pose a risk to humans and wildlife, but it concluded the evidence was inadequate to suggest the low-level exposures from the environment pose any risk. The NRC report should have ended the ED scare. An October 1996 NRC report pulled the plug on the scare over electric power lines causing cancer. But then again, the power line scare hadn’t been enacted into law. The scare’s new round comes from Dr. John Brock, a researcher at the U.S. Centers for Disease Control and Prevention. Brock’s will report higher-than-expected levels of an alleged ED — “di-n-butyl phthalate” or “DBP” — were detected in human urine samples. News of the study was leaked to The Hartford Courant last week. The study won’t officially be published until October when it will appear in the U.S. Government journal, Environmental Health Perspectives. It will appear on the Internet, though, on September 1, according to CDC. Foreshadowing the coming hype, the Courant quoted lead researcher John Brock saying DBP was detected at “[levels] higher than we anticipated” and at “levels we are concerned about.” Brock added, I can tell you that we’re going to be working on phthalates for a long time here at the CDC.” What are Brock’s results? Should you be concerned? Brock didn’t return any of several phone calls requesting an interview. He apparently felt the leak to the Hartford Courant constituted sufficient disclosure for now. But Brock presented his results several months ago at a closed-door meeting in Europe. First, though, here’s some background on DBP. DBP is used in the manufacture of cellulose plastics, dyes, food packaging, perfumes, skin emollients, hair spray, nail polish, and insect repellents. Chemical Industry Institute of Toxicology researchers reported in a recent issue of Toxicological Sciences no effects observed in rats given a DBP dose of 50 milligrams per kilogram of bodyweight per day during a key part of the gestational period. At twice this dose, about one-third of the rat pups showed a mild effect (retaining circles around their nipples for a longer period). At a dose 10 times the no-effect level, hypospadia, (a birth defect of the urinary tract) was observed in fewer than 10 percent of the animals. “Acceptable” levels of human exposure to chemicals are typically set 100 times below the no-effects level in animals. There’s no scientific basis for using 100; it’s a convention believed to provide a large safety margin. When animal data involves birth defects, like for DBP, the acceptable level of exposure is set 1,000 times below the no-effects level to be even “safer.” Brock estimates an average exposure to DBP among his sample was about 30 times below the “acceptable” level in humans, according to sources. His estimate at the 95th percentile level of exposure is almost 5 times below the “acceptable” level. Brock’s worst-case estimated exposure is about 3.5 greater than the “acceptable” exposure level. For unknown reasons, the subgroup in Brock’s population with the highest estimated exposure are women of childbearing age. So birth defects are the outcome of concern. The “big deal” — if Brock’s data is sound and his guess-timates of exposure is reliable — is that, in the worst case, a pregnant woman might be exposed to DBP at a level “only” about 278 times less than the no-effect level in rats and about 2,780 times less than the level at which 10 percent of rat pups are reported with hypospadia. Where’s the danger? Brock’s dubious result is no doubt why he resorted to publication with Environmental Health Perspectives. The less-than-rigorous journal once published a study featuring a weak statistical link between low-levels of air pollution and sudden infant death syndrome — though the researchers never considered a myriad of other possible causes for the reported cases of SIDS. Publication was timed to help EPA battle for stricter air pollution standards. EHP also editorialized against skeptics of global warming theory by likening them to the tobacco industry. EHP is a journal with an agenda — and the agenda isn’t science. Brock has a similar problem. Despite employment with CDC, Brock is a well-known activist-scientist. He signed “consensus statements” with other notorious advocates of the endocrine disrupter theory. These statements say, among other things, “We are certain... endocrine-disrupting chemicals can undermine neurological and behavioral development and subsequent potential of individuals in the womb...” But it’s difficult to square this “certainty” with the National Research Council’s conclusion there was no persuasive evidence supporting the ED theory. Coincidentally(?), the Hartford Courant article featured extensive quotes from Brock’s fellow consensus statement signatories — the University of Florida’s Louis Guillette, Jr. and the EPA’s Earl Gray. Guillette said “[Brock’s study is] going to rewrite how we look at phthalates.” Gray expressed “concern” that more chemical testing was needed. Brock and Guillette co-authored a study failing to link small penises among alligators from Florida’s highly polluted Lake Apopka with chemicals. Was the Hartford Courant reporting news or a class reunion of alarmists? Adding to the ho-hum of Brock’s study and the undeniable agendas of Brock and EHP, is DBP’s track record. DBP has been used in industrial process since 1900. Scientific study of DBP dates back to at least 1953. There is not a single study that links exposure to DBP with any human health effects — including Brock’s. The good news is the DBP scare doesn’t have a leg to stand on. The bad news, of course, is that facts don’t matter to Brock and his ilk. When this round of the endocrine disrupter scare fades, the bell will soon sound for another. Steven Milloy is a biostatistician, lawyer, adjunct scholar at the Cato Institute and publisher of JunkScience.com. |