A Chemical Kick to the Gut

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One doesn’t need pugilistic experience to feel the effects of a “sucker punch.” We’ve all experienced different versions of the cheap shot in our daily lives—we’re expecting one thing and get waylaid by something altogether different, something we weren’t prepared for. Say you’re being a good defensive driver, keeping your eyes peeled for all those Hummer owners jacked-up on Red Bull and talk radio, when a chunk of airplane engine plummets to earth, flattening your ’94 Ford Escort (and you). That’s a sucker punch. Or walk into a meeting prepared to talk about a project you’ve been diligently working on, only to find your boss wants to know about the one you’ve been blowing off, the one you thought all the bigwigs had forgotten about. Ouch. Well, there are increasing signs that society at large is getting sucker-punched by agrichemicals. We’re looking one way, and an insidious threat is sneaking through the back door. Fortunately for humans, there are frogs. And some of those amphibians are taking a few punches to the chin, providing an early warning that a devastating roundhouse is on its way.

The connections between agrichemicals and certain health effects such as cancer have been known for several years. We know the routine: scientists expose rats and other lab critters to high levels of toxins for extended periods of time. Then a paper is published showing that an alarmingly high proportion of those organisms developed ailments after the exposure. Such research is important, but is often dismissed by apologists for the chemical industry as unrealistic: nobody would be exposed to such intense dosages in the real world, goes the argument. What critics of these lab studies fail to acknowledge is that this kind of research has prompted wider field science that is showing a frightingly real-world connection between exposures to agrichemicals and negative health effects in humans.

For example, more than 89,000 people are participating in the Agricultural Health Study, directed by the National Cancer Institute, the National Institute of Environmental Health Sciences and the U.S. Environmental Protection Agency. Launched in 1994, this massive study is examining farm families and pesticide applicators in Iowa and North Carolina. The study is finding there may be a link between being an agricultural worker and increased chances of having certain cancers, including leukemia, myeloma, non-Hodgkin’s lymphoma, and cancers of the lip, stomach, skin, brain and prostate.

Despite such solid field research, detractors continue to focus in on lab studies that feed rats a lifetime’s worth of carcinogens in a month’s time. Meanwhile, as we all argue over the viability of such studies, the issue of low-level, “pulse” exposure to pesticides is all but ignored.

The concerns is that even seemingly “safe” levels of these chemicals have negative impacts on development, growth and reproduction. There is a growing group of toxicologists who believe short-term “pulse” doses of these chemical mixtures — some at levels never before considered toxic — can in some cases have a more negative impact than long-term, high dose exposure.

It’s all about timing. A mother may show no health problems as a result of a certain levels of exposure, but she’s in a different state of susceptibility than her baby. Thus, the baby could be negatively affected by doses that are harmless to adults.

The effects of low doses of chemicals on human development was covered extensively in the 1996 book, Our Stolen Future. This book laid out evidence that low levels of pesticides and other toxic chemicals may be disrupting the endocrine system in animals, and pose a real threat to human beings. To grasp the importance of such a disruption, consider that the endocrine system controls the key development engines in our body, including systems that manage growth, development and reproduction.

The book summarized growing evidence that “endocrine-disrupting” chemicals cause reproductive abnormalities, reduced fertility, behavioral abnormalities and population declines — particularly in top predators. In short, the old saw “the dose makes the poison” is in need of some modification, say toxicology experts.

Consider research that’s been conducted by people like the University of Minnesota’s Vincent Garry. Garry has studied the river of records produced by our society’s desire to document everything from a baby’s birth weight to the kind of weed killer his or her father used the month that baby was conceived. They’ve published research results that should send chills down the spine of anyone who has raised children in a rural area.

For example, their research has shown that in the Red River Valley, where intensive production of wheat, sugar beets, corn and potatoes leads to heavy use of chemicals, the children born to pesticide applicators had a increased chance of having a birth defect when compared to children born to non-pesticide applicators in the region, as well as children born in parts of the state where agricultural chemicals are not used extensively.

And if that baby was conceived in the spring, that increased its chances of having a birth defect even more. When compared to their springtime counterparts, birth defect rates in autumn-conceived babies were almost half in some cases. In the Midwest, spring planting season is when the majority of agrichemicals are applied.

These results echo the conclusions of similar analyses done in Iowa and Nebraska. Nothing definitive has been nailed down yet, but the implications are frightening.

Most people associate pesticide exposure to the amount of herbicide spray left on vegetables once they reach the supper table. As a result, laboratory studies focus on ingestion through the mouth, or even direct injection into the bloodstream. But what about intake via drinking water, breathing contaminated air or absorbing it through the skin?

And in an attempt to make pesticides less of a threat to our ground water, chemical companies are making their products more volatile. That means they dissipate in the atmosphere quicker after being sprayed on a field, instead of hanging around long enough to be washed into a river during the next rain storm. But such volatility could make it easier for these chemicals to enter our bodies through the skin or the respiratory system.

Are pregnant women, with their higher water retention and respiration rates, more likely to take in toxic levels? Garry has been wondering that since 1987, when he investigated the tragic death of a 24-year-old woman who was seven months pregnant. Within a few hours of being exposed to a pile of grain saturated with a bug killing fumigate, the woman went into cardiac arrest and died. Garry’s investigation raised questions about whether a pregnant woman’s altered metabolism increases her intake of toxins.

Which brings up those frogs that tend to grow legs in inappropriate places. It’s been a dozen years since a group of middle-schoolers found leopard frogs with creature-feature deformities near Henderson, Minn., but the debate still rages over what causes these growths.

Research conducted by people like the University of California-Berkeley biologist Tyrone Hayes points the finger at atrazine. That’s a problem in the Corn Belt, because atrazine is the most widely used herbicide in the United States. It’s quite effective at controlling pesky weeds in Minnesota corn, making it the go-to chemical for crop farmers (a little less than 2 million pounds of atrazine was sold in the state in 2005). But its widespread use means it is one of those chemcials that most commonly shows up as a contaminant in ground and surface waters.

Research conducted by Hayes and his colleagues shows that exposure to the herbicide has severe impacts on frogs, including chemically “castrating” the amphibians at levels as low as 0.1 parts per billion. For the average person, trying to comprehend how “parts per billion” is relevant to our daily lives is like comparing the national debt to your checking account. But maybe putting up some other “parts per billion” comparisons will help:

• In Minnesota, the drinking water standard for atrazine in public water supplies is three parts per billion, which is a level set by the U.S. Environmental Protection Agency.

• The state limit for atrazine in private wells is 20 parts per billion.

• At times, atrazine levels in southeast Minnesota’s Whitewater River surge as high as 30 parts per billion.

That last figure comes as a result of water monitoring conducted by hydrologist Paul Wotzka from 1993 until this past October. Wotzka, a highly respected reseacher, conducted the monitoring as an employee of the Minnesota Department of Agriculture; he now works for the Minnesota Pollution Control Agency. As the March-April Minnesota Volunteer reports, atrazine showed up constantly in Wotzka’s samples, and between 2001 and 2006 levels increased dramatically. It goes without saying that corn and soybean plantings in that part of the state have increased in recent years, coming at the expense of diverse crop rotations, pastureland and other systems that don’t require heavy dosages of pesticides to stay viable. It also goes without saying that the ethanol boom will put even more acres under corn — which means more atrazine.

Frogs aren’t humans, but they are key indicators of what’s going on in our ecosystem. Since they spend so much of their early lives in water, anything present in that water during those developmental stages is likely to show up later in life. Remember: it may not always be the dose that makes the posion, but the timing of that dose.

There have been legislative attempts — none successful — to regulate the use of atrazine in Minnesota. Agrichemical interests and their allies are understandably concerned about any restrictions on one of their herbicidal workhorses. This session, Rep. Ken Tschumper and Sen. John Marty have introduced legislation (HF 1986 and HF 1997; SF 2093 and SF 2056) that could go a long way towards helping us deal with the atrazine problem. These bills, among other things, would make Minnesota’s atrazine limits for private wells three parts per billion, bringing them in line with the limits for public water supplies. The proposed legislation would also require the Minnesota Department of Health to review the scientific evidence surrouding the health impacts of pesticides such as atrazine. These are not extreme steps by any measure. After all, the European Union has banned atrazine outright.

In March, Professor Hayes came to Minnesota to testify in favor of the legislation. That alone is a victory of sorts in the battle to get the word out on atrazine — a few years ago Minnesota Pollution Control Agency officials “dis-invited” him from being a keynote speaker at an MPCA conference after agribusiness raised concerns over his research.

But don’t expect smooth sailing for any proposed legislation related to a big money-maker like atrazine. Chemical giant Syngenta Crop Protection, which manufactures the herbicide, has been particularly aggresive in attempting to undermine Hayes’ research. And interests representing large agribusiness in Minnesota aren’t thrilled about research done in places like southeast Minnesota and the Red River Valley that raises troubling questions about certain chemicals.

The opposition to asking and acting upon such questions may be massed stronger than ever. But don’t get distracted by their rhetoric. Remember when the tobacco industry denied cigarettes were bad for you? Thanks to the frogs, we’re running out of excuses for getting sucker-punched.

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