February 9, 2012
Don’t drink tap water. Beware the coming environmental apocalypse. It’s election season, and advocacy groups are turning up the heat on the Environmental Protection Agency. Will the Obama Administration buckle in this über-political time and give in to alarmism?
The target du jour is atrazine, the American farmer’s most popular weed killer, but it’s really modern chemistry that’s under assault. In case you missed it, Mother Jones magazine’s February issue rained frogs on American farmers for using atrazine. On Tuesday, PR Watch released a three-part series attacking its manufacturer, Syngenta, for attempting to “shape” news reports—in other words, to defend itself against the attacks exemplified in these articles.
This sudden burst of advocacy journalism shares a common theme besides End of Days hysteria: a devastating lack of respect for science. Mother Jonesand PR Watch are known for channeling anti-chemical organics producers and working closely with class action lawyers, who in this case are attempting to back the EPA into a political corner for vast financial gain.
The agency is expected to complete its latest review of the chemical later this year. Will it follow the expected recommendations of its own science panel and relax out-of-date standards, or will it cave to political pressure in an election year and punt the decision, or even tighten restrictions?
Atrazine is an odorless powder applied to control weeds that would otherwise choke a crop and starve it of nutrients. It degrades quickly, does not bio-accumulate in organisms and is considered so comparatively gentle to crops that it can be used even after the first shoots appear above the ground. A study commissioned by the EPA concluded that it boosts yields by 6 percent or more, saving corn farmers as much as $28 per acre—more than $2 billion in annual economic benefits. But to anti-chemical activists it’s a ticking time bomb.
The atrazine-will-destroy-us-theory rests substantially on the credibility of the research of Tyrone Hayes. The controversial University of California endocrinologist—and Hayes almost alone among experts—claims that microscopic levels of atrazine found in some drinking water supplies are carcinogenic and distort human development.
The protagonist of his theory and both the Mother Jones and PR Watch hit pieces is Darnell, one of Hayes’ colony of male African clawed frogs that are literally swimming in high levels of atrazine. In the latest of a series of such papers, in March 2010, Hayes and his student co-authors argued that atrazine produces males with ambiguous genitalia and soprano-like croaks—hermaphrodites, like Darnell. Hayes claims that humans are equally as vulnerable.
This decade-old narrative, horrific if you’re a frog trapped for life in Hayes’ laboratory atrazine brew, has been the staple of Environmental Working Group, Pesticide Action Network, Natural Resources Defense Council and other activists calling for its ban. After all, if it can turn Jack tadpoles into Janes, would you risk your child with tap water?
The science answer, which is more complicated and less emotionally satisfying than knee jerk reactions and hysteria: Extensive research concludes there is no substantial risk to humans or frogs for that matter from atrazine. In fact, international regulators are relaxing standards on atrazine as evidence accumulates of its comparative safety.
The Australian Pesticides and Veterinary Medicines Authority reviewed the most recent Hayes study, finding the lab work flawed, reaffirming its conclusion that atrazine is safe as used. Scientists have determinedly tried to replicate Hayes’s findings to no avail. An unprecedented state of the art study by biologist Werner Kloas of Berlin’s Humboldt University—who is an outspoken supporter of precautionary bans on chemicals—showed no impact on frogs from atrazine exposure, low doses or high.
There is no field evidence to support his claims, either. “[W]e found that in those kinds of landscapes where corn is being grown, the great majority of the ponds we sampled didn’t have any deformities at all,” wrote Yale School of Forestry & Environmental Studies professor David Skelly, who Mother Jonesbizarrely tries to portray as an admirer of Hayes. “To my knowledge (and I have participated in two EPA panels that reviewed available results) nobody else has been able to get this ultra low concentration effect.”
Yes, we should be concerned about the ecological impact of environmental chemicals, but the real heat in this debate revolves around claims that frogs are good proxies for humans. They’re not. Amphibians are permeable beings that absorb moisture and some of their oxygen through their skin. We don’t swim our lives away in atrazine. They don’t swallow water like we do.
High tech detection equipment may help scientists identify a thimble full of a chemical in Lake Erie, but the mere presence of a compound in water does not necessarily present a threat. According to the National Institutes of Health, studies have consistently shown that “a risk to human health [from atrazine is] essentially nonexistent.” But you’d never be presented with these eye-opening facts from reading the blogosphere echo chamber, or the New York Times, for that matter.
Let me walk you through the process of how hysteria over atrazine is manufactured. In 2009, the NRDC made headlines with “Poisoning the Well,” a widely challenged investigation promoted in an equally problematic Timesreport soberly titled “Debating How Much Weed Killer is Safe in Your Water Glass.” Their key revelation: three water systems in the United States had occasional atrazine “spikes” above 3 parts per billion—which they said posed grave threats to humans. (For context, one part per billion is equivalent to ½ teaspoon of water in an Olympic-sized swimming pool … or 2.5 seconds in a lifetime.)
Following the lead of the Times, the media exploded with breathless stories of killer atrazine cocktails in our water supply. A few months later, the EPA cited the NRDC investigation in announcing it would again evaluate atrazine, barely three years after it had completed one of the most exhaustive scientific investigations ever undertaken, exonerating the chemical.
Are we in danger? Scientists, almost universally, say ‘no’. In 1989, the Safe Drinking Water Act set what is in effect “guideline values” for atrazine. That’s the 3ppb level that prompted the NRDC to yell fire in a movie house. But let’s be clear here. This is not the level at which a person would be harmed by atrazine exposure. It’s a level designed to signal authorities that they should attempt to identify the source of a chemical and take action to prevent further incursions.
What then is a safe drinking water level? Regulators call that a “no observed effect” level. A basic principle of toxicology is that at a high enough dose, all substances are toxic. Although chemicals are often referred to as “dangerous” or “safe”, as though these concepts were absolutes, in reality, these terms describe chemicals at various does that cause toxic effects. The no effect level is the lowest possible point at which no harm, including endocrine disruption, is detectable on the most sensitive known animal exposed to a chemical. For atrazine, it’s not the 3ppb guideline value brandished by advocacy groups. It ranges from 30,000 to more than 100,000 times less stringent—figures confirmed by the EPA.
Said another way, while the EPA says that water systems should address possible atrazine contamination when supplies average more than 3ppb for a full year, humans are not in harms way, based on animal tests, unless exposure levels are far far higher—as much as 350,00ppb!
Poisoning frogs—or facts?
Why the huge discrepancy? Because regulators add safety buffers beyond the no effect level. It’s standard for international regulators to increase the safety margin for chemical exposure by a factor of 100. In the case of atrazine, additional safety buffers were added years ago that exaggerate concerns. For example, the EPA added an additional buffer of 10 because it was originally believed atrazine causes cancer. They’ve since determined it doesn’t. Regulators also multiply by five times based on the assumption that 20% of our daily exposure comes from water, when the actual figure is 100%. (No atrazine is found on crops because it’s a pre-emergent weed killer.) The EPA’s Science Advisory Panel has taken voluminous testimony that the agency should follow the lead of other international regulators and dial back on these outdated, exaggerated multipliers.
So let’s go back to those field tests on atrazine. More than a decade of EPA data shows the average running exposure to atrazine in drinking water is less than 1 ppb. NRDC found—OMG—three water systems in which atrazine levels spiked for one day into the 20-30ppb level. In fact, the highest level ever recorded in treated water is 64ppb. Compare those numbers with the no effect levels for atrazine of 63,000-350,000ppb. Calling the NRDC’s claims, now mindlessly re-circulated by Mother Jones and PR Watch, hysterical is giving a genuine psychological disorder a bad name. It’s plain dishonest.
Recognizing the absurdity of current standards, the World Health Organization recently relaxed its guideline threshold from 2ppb to 100ppb. WHO also noted that the potential danger of endocrine disruption—the centerpiece of Hayes’ argument—are almost non-existent in humans at this level.
“I consider even that 100ppb figure very, very conservative,” said Les Davies, principal scientist with the Australian Pesticides and Veterinary Medicines Authority, who was part of the team that reassessed the chemical for WHO.
“Members of the overly-concerned public often think that they are absolute health cut-offs and that anything above the guideline will be poisoning them,” said Davies, who is concerned that advocacy groups stir unnecessary fears by promoting thresholds thousands of times more conservative than pose genuine danger.
“All compounds are toxic, everything,” Davies told me. “Activists just see a toxic study and immediately jump to recommending bans. There would be chaos if regulators responded to those fears. We are mandated to set levels that reflect real health problems, not fear levels.”
Environmental challenges are complex. Data is more important than ideology. If the EPA capitulates to hysteria, it will have a serious impact on the world food supply and the nutritionally poor, who depend on plentiful crops. It will hurt our economy. Most devastating, it will be a decisive, perhaps irreparable blow against sound science.
Jon Entine is director of the Genetic Literacy Project and senior research fellow at STATS and the Center for Health and Risk Communications at George Mason University.