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Scientists Say New Farm Chemical 'Will Cause Disease and Illness'

Strawberry growers are planning to fumigate their crops with methyl iodide, a carcinogen and neurotoxin that can cause miscarriages and other medical problems.

California pesticide regulators plan to approve a new agricultural chemical to sterilize the soil of strawberry fields, but state records and interviews with scientists raise questions about whether workers and nearby communities can be adequately protected from the highly toxic chemical.

Currently, strawberry growers use a fumigant called methyl bromide, which is being phased out around the world because it damages the ozone layer. But the alternative, methyl iodide, a carcinogen and neurotoxin that can cause miscarriages and other medical problems, is considered far more toxic than methyl bromide.

In interviews with KQED's "Quest," members of a scientific review panel that examined the potential use of methyl iodide said it was clear to them that exposure levels would far exceed what they, along with staff scientists, had deemed safe.

"I understood those levels were unattainable," said panel member Edward L. Loechler, a professor of biology at Boston University. "It was blatantly obvious that those levels were unattainable."

The panel's chair, John Froines, a professor in the Department of Environmental Health Sciences at UCLA, said, "I honestly think this chemical will cause disease and illness. And so does everyone else on the committee."

Lea Brooks, a spokeswoman for the California Department of Pesticide Regulation, which has approved the use of methyl iodide, said in an email that risk managers at the agency have concluded that the chemical can be used safely "with the strict safeguards proposed."

"No pesticide," she said, "has been evaluated more than methyl iodide in the history of the Department of Pesticide Regulation."

Brooks said methyl iodide's approval comes with a list of required safeguards – tools like buffer zones and respirators – intended to keep workers and bystanders safe from inhaling dangerous levels of the chemical.

Farmers who use methyl iodide would be required to create buffer zones of 200 feet or more, depending on the number of acres being fumigated. The buffer zone would be extended to a half-mile for schools, hospitals and daycare centers.

At Gavilan View Middle School in Salinas, where little league teams practice just yards away from commercial strawberry fields, fumigation companies would have to ensure that the school remained vacant for 48 hours.

The buffer zones proposed for methyl iodide are similar, though more stringent, than what's required for methyl bromide.

In interviews, strawberry pickers said that buffer zones are generally enforced when fumigators are working in nearby fields. They said that they sometimes smell fumes, which drift across the fields.

"Sometimes you feel nauseous, or your head aches," said Alejandra Nolasco Campos, a mother of two who works in the Salinas-area strawberry fields. "But if you feel bad and you sit down for a while, then once you’ve recuperated, you head back."

Campos says that, like many women in the fields, she worked through the first five months of her pregnancy. Since methyl iodide is a neurotoxin that can cause miscarriage, scientists on the panel were particularly concerned that it could harm the brains of developing fetuses.

"The endpoint you're basing this on is death," said Loechler. "Even if the fetuses aren't dying, they may be experiencing other impacts that are subtler than death, but still serious."

Episodes of pesticide "drift," such as those described by Campos and other farm workers, are hard to count, because they're only recorded when workers end up in the hospital as a result of their exposure. According to the Department of Pesticide Regulation, there were an average of 37 such incidents each year between 2000 and 2007.