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PRI's Environmental News Magazine

Dursban Restrictions

Air Date: Week of May 26, 2000

The Environmental Protection Agency is about to make public its new restrictions on Dursban, one of the most widely used pesticides in the U.S. Steve Curwood speaks with Sue Darcey, editor of Pesticide Report, about the potential health risks of the chemical and the uses the EPA is likely to ban.

Transcript

CURWOOD: Dursban is one of the most widely-used insecticides in the U.S. You can find it in consumer roach and ant sprays. It's often the active ingredient in the flea and tick collars put on pets. Exterminators use Dursban to kill termites, and farmers apply it to fruit crops. The chemical is so pervasive that some scientists estimate more than 80 percent of adults have detectable levels of it in their urine. Last year the Environmental Protection Agency said Dursban might pose a health threat, especially to children. The chemical affects the nervous system. With that in mind, the EPA is expected shortly to announce restrictions on the use of Dursban. Sue Darcey is the editor of Pesticide Report, a newsletter covering that industry. Sue, last year the EPA released its preliminary report on the risk of Dursban. The agency cited research that found this chemical, which also goes by the name chlorpyrifos, hung around in the air a lot longer than originally thought. Did those studies consider if it was being used according to directions?

DARCEY: Oh, yeah. There was one primary study, the Rutgers University study, where they took normal levels that a pest control operator would spray around an apartment. And they sprayed it according to label directions, around the perimeters of apartment, crack and crevice-type treatment. And then they just took air monitoring samples over the next three or four days, and they found that the residues of chlorpyrifos did not decrease at the amount that they thought it would. It particularly clung to plush things like carpets, couches, children's toys.

CURWOOD: There are some studies about the effect of Dursban on young brains, on developing brains.

DARCEY: Mm hm. Basically, they show that the young rats and mice have slower reaction times. They might have an awkward gait when they walk. They have problems completing mazes and finishing tasks that normally they could do very easily.

CURWOOD: And it doesn't seem to take much to cause an impact, does it?

DARCEY: No, it doesn't. It all has to do with the day when the fetus is exposed, according to rat or mice studies. If you apply a certain dose at a very low level on the tenth day of gestation, then that's all it takes for the developing mice, when they're born, to start manifesting all these neurological effects.

CURWOOD: The Dow Chemical Company makes Dursban. What does it say in response to these studies?

DARCEY: It says that chlorpyrifos, which is the active ingredient in Dursban, has been thoroughly studied. I think they say they've done 3,600 studies, and that it's perfectly safe. And the only time anyone should experience any harm is if there was a horrible accident. But other than that, they say that normal use according to label directions would never cause harm to a person.

CURWOOD: Now, apparently Dow and the Environmental Protection Agency are in negotiations, or they have been in negotiations over the use of Dursban. Tell me why the EPA would negotiate at all, and what the word is on how those talks are going.

DARCEY: EPA just doesn't go in willy-nilly and, you know, slap a ban down on a pesticide. That would be incredibly unusual. They usually say, are there ways that you can tweak the use of this chemical? Perhaps you might want to stop using it as a termiticide, if that seems to be the main problem. And then we'll continue to allow you to use it on crops, where you're getting your most money from the profit anyway.

CURWOOD: Is Dow in the mood to negotiate?

DARCEY: Dow is facing a lot of lawsuits, in which people say they've been harmed by chlorpyrifos. And they're a little bit concerned that if EPA makes a decision that would ban or cause Dow to voluntarily cancel some uses, that even more people will come out of the woodwork and say, hey, I've been hurt by chlorpyrifos, too, and that they would file a lawsuit. And then Dow would have a real headache on its hands.

CURWOOD: So I'm wondering, if the negotiations between the Environmental Protection Agency and Dow go nowhere, what kind of restrictions do you think the EPA will end up imposing on the use of Dursban?

DARCEY: I think they would probably make it a restricted-use pesticide, where it couldn't be used around people's home except by a professional applicator, who's been licensed and trained to use it properly.

CURWOOD: What about restrictions on crop use?

DARCEY: You know, I would think that would be the last thing EPA would go for, unless they decide to change some of the risk assessment numbers -- instead of -- there's something called the 3x factor and the 10x factor.

CURWOOD: Can you explain that? What do you mean by 10x?

DARCEY: Well, right now the EPA is applying what they call the 3x factor. The 10x factor would apply a larger buffer or a margin of safety to the pesticide. There's been a big push from environmental scientists and pediatricians to up that to a 10x. And if EPA ups it to the 10x, then probably some agricultural uses are going to be hit. I would predict apples, for example, because that's the heaviest use of chlorpyrifos in agriculture.

CURWOOD: Sue Darcey is editor and publisher of Pesticide Report. Sue, thanks for speaking with us today.

DARCEY: Sure.

 

 

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