EPA Reviews Hints Of Weed Killer's Fetal Risks

In the February 11 Issue:

EPA reviews hints of weed killer's fetal risks

By Janet Raloff

Web edition : Thursday, February 4th, 2010

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Last October, the Environmental Protection Agency announced it was reopening what the pesticide industry had hoped was a closed chapter on allegations of a popular herbicide’s toxicity. The agency will be convening meetings of its Scientific Advisory Panel on pesticides throughout 2010 to probe concerns about the safety of atrazine, a weed killer on which most American corn growers rely.

The first meeting of these outside experts started Tuesday. And although a large number of studies have indicated that atrazine can perturb hormones in animals and human cells — and might even pose a possible risk of cancer amongst heavily exposed people, these outcomes were not the focus of EPA’s review Tuesday. Risks to babies were.

During the SAP’s morning session, Aaron Niman, an EPA scientist, reviewed five recent studies linking atrazine to birth defects and other risks in newborns.

Two of the papers he cited were by Paul Winchester of the Indiana University School of Medicine and his colleagues. The most recent of these papers linked the presence of agricultural chemicals in surface waters around the nation — especially atrazine — at the time a woman conceived a baby to a heightened risk that her infant would develop a serious birth defect. This risk, although not huge, was statistically sound, he noted.

I’ve talked about this with Winchester, and he acknowledges that this link is no slam dunk in terms of indicting atrazine.

The U.S. Geological Survey data on contaminants in surface water around the nation, which Winchester’s team used, turned up plenty of agrochemicals. Take the White River in Indiana, Winchester says, “one of the study sites that is particularly relevant to me: In every sample, [USGS] found a mixture of pesticides. But far and away the most prevalent pesticide — and the one which exceeds the [federal] safety limits most often — is atrazine.”

Niman noted that this study, published almost a year ago in Acta Paediatrica, was unable to calculate probable atrazine exposures for each U.S. mom who gave birth over the study period: 1995 to 2002. He noted that this is a limitation of such “ecologic” studies, which analyze trends “at the group level” — such as the data, used here, on all births reported to the Centers for Disease Control and Prevention over that period. But “its strength,” Niman said, “is that it provides sort of an overall snapshot of trends in both birth defects and atrazine levels in the environment.” As such, he argued earlier this week, these ecologic studies are “useful in hypothesis generation,” even if they can’t establish causality.

Indeed, Winchester argues, even if atrazine isn't the operant risk factor, that won't necessarily let agrochemicals off the hook. A number of studies that he’s recently been reporting at scientific meetings have shown, he says, “that preterm birth rates at the population level are significantly increased by pesticide exposure” and that among Californians exposed to farm chemicals, “birth weights are lower in more heavily exposed pregnancies.”

These trends really disturb the neonatalogist because “the number one reason I’m in business is birth defects and preterm births. Those are the two things that kill babies. And we’re very disturbed that both have been increasing steadily over the last two decades.” So it's imperative to find out what is contributing to these trends, he says. And small babies: “Lowering birth weight percentiles will cause delays in physiological maturity in preterm babies,” he notes.

Niman spent a lot of time Tuesday also reviewing another study by researchers in the Hoosier State, this one by Hugo Ochoa-Acuña and his colleagues at Purdue. It mined drinking-water-contaminant data to calculate when women in the state would have been most exposed to atrazine.

In a paper published last October in Environmental Health Perspectives, the scientists linked relatively high atrazine concentrations in the drinking water to which a woman had access late in pregnancy with an elevated chance that her baby would be born especially small for its gestational age.

Niman described this as “probably the strongest of the studies” that he reviewed on possible fetal risks for the SAP, because it included individual atrazine-exposure estimates, contained drinking-water-atrazine data over a period of years, and established birth weights — the outcome of concern — from state registries.

Such a study still can’t conclusively link atrazine to problems in babies, Niman acknowledged, but it points to where further research is warranted.

Tim Pastoor, principal scientist for Syngenta Crop Protection of Greensboro, N.C., disagrees. The studies that Niman reviewed “all have fundamental flaws," he said. For example, the increased incidence of birth defects that Winchester’s group found in spring, when atrazine is heavily used, could just as easily have been linked “with almost any other seasonal occurrence, including rainfall, lightning strikes, and tornadoes." Indeed, he noted in a prepared statement yesterday, “the same uptick in birth defects in spring months is seen throughout the United States, regardless of atrazine usage."

Counters Winchester, environmental contamination with atrazine can be found throughout most of the nation, as a recent USGS map illustrates. Even in areas that ostensibly use relatively little of this weed killer, he says — well outside the Corn Belt, for instance — atrazine is commonly found tainting water. Perhaps from its use on turf.

Or perhaps atrazine shows up far from where it was applied because its persistence allows it to move widely around the environment, posits Tyrone Hayes, a biologist at the University of California, Berkeley. This scientist, who has studied atrazine’s impacts on amphibians, said a USGS scientist, Perry Jones, told him that residues of the weed killer can travel long distances with the wind. Indeed, Hayes reports that Jones told him USGS “can measure atrazine in the rainwater in Minnesota that was applied in Kansas.”

Clearly, plenty of people value atrazine. EPA is now reevaluating the long-used weed killer to probe whether science confirms that babies and others aren’t suffering undue risks from this chemical’s continuing widespread use.

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Comments 6

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Yawn, more bureaucratic job security. Not requiring the EPA to account for the costs of it's semi-sane activities was a criminal stupidity.

ART DAY

Feb. 7, 2010 at 6:48pm
ART DAY…Yawning is contagious. Your reflexive indictment of the EPA’s relatively miniscule budget indicates that your opinions are suspect because you have your head firmly lodged where the sun don’t shine. No apologies for the flame from this old farm boy because you started it with “criminal stupidity.”

Frank Mosier

Feb. 8, 2010 at 10:27am
The studies you described, Janet, all sound inadequate for determining if atrazine is the culprit or an innocent bystander. How frequently are these atrazine-tainted waters checked? What other chemicals are present during those same time frames? How do their levels rise and fall? Atrazine may or may not be causing these birth defects, but nothing in your article leads me to believe that the EPA will arrive at a meaningful, substantive conclusion. It will likely be "more data needed" and so forth. If they do reach a meaningful, substantive conclusion based on the evidence you reported, it will be suspect and open to challenge.

Robert Woodman

Feb. 9, 2010 at 12:07am
I agree with Frank's assessment of Art. (Warning: flame coming) He's a moron.

However, the ecological studies in question don't prove much. It would be so much easier to perform the definitive studies in rats, mice, rabbits, etc. to see if there's any trend towards humans.

The confounders in causing low birthweight in human populations are so large that teasing out the effects of atrazine in an ecological study would be difficult if not impossible. For instance, low birthweight is caused by smoking, drinking, malnutrition, mutations, numerous other toxins, etc. Low birthweight is associated especially with poverty and that makes it really hard for everybody. Would it be cheaper to raise a population's income or to establish more neonatal care centers?

The cost of raising income could be offset by hiring poor people to pick up garbage on the streets, dig ditches, build sidewalks and bridges, etc. Building more neonatal emergency centers generates more costs by fostering charges for physician's services, drugs, procedures, and so on. Whereas if the population had more income, they could pay for their own health care.

The EPA, sadly, has little money, and to make matters worse, has barely begun to recover from massive politicization by the last Republican administration (I hesitate to use the name of the politicizer-in-chief.) In a perfect world, the EPA could pay for studies of the 3000 or more compounds at play: definitive studies in apes or chimpanzees, in which nutrition and chemical exposure could be controlled. But this isn't a perfect world. We (the left) are having enough problems getting basic good ideas (like government control of the health industry to reduce costs and deaths) into force.

That's right, Art: I said it. Government control of the health industry. Health insurance is a joke. You can't insure health as if it were earthquakes or fires. The health insurance industry is a cancer feeding on the public. 30 per cent of the cost of private health "insurance" is "administrative costs" (read: paper shuffling jobs and profit.) But Medicare spends less than 10 percent on administration, more like 5%. Why? because they don't waste time verifying eligibility and trying to figure out ways to deny coverage on the basis of pre-existing conditions or fine print in the policy.

Mark my words: the public option is the ONLY way to reduce healthcare costs. That's not in the health reform legislation, even if it passes. Costs will continue to spiral as private parties seeking a profit continue to gravitate towards medicine, the cash cow. Every aspect of medicine today is riddled with profit-taking, from drugs to imaging machines.

Enough soap-boxing. But I'm not kidding, Art. You're stuck in the stone age if you think government (under our near-holy Constitution and Bill of Rights), even big government, is wrong. Good government is better than profit-taking individuals running things. It's a scientific fact (small levity there.)

Conrad Seitz

Feb. 9, 2010 at 7:03pm
As EPA's Niman argues, such human data are anything but conclusive...just good for hypothesis testing. Which, by the way, is actively underway--probing atrazine's mechanisms of action in animals and cell lines. Some of the data from these studies will be reviewed in a feature story coming out in the next issue of Science News. More will also be coming out in a separate online piece within the next couple weeks (when an embargo on one of the papers breaks).

jar

Feb. 10, 2010 at 2:06pm
I am a farmer from Minnesota and The fact is Atrazine is a obsolete chemical. I doubt if any modern and successful farmers would use it. We quit over 20 years ago for economic reasons. It is time for chemical companies to tell us the truth or that they don't know. Atrazine is in most farm wells that are less than 100 feet deep. If the chemical companies had told me I would be drinking it for the rest of my life I wouldn't have purchased it in the first place. RA

Rodney Anderson

Feb. 17, 2010 at 8:58pm

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