California is considering licensing for agriculture a chemical that a group of highly regarded chemists says they use only with “great precautions to avoid exposure”—even under laboratory conditions. Methyl iodide, a “cousin” of methyl bromide, is spread as a fumigant over fields, often prior to planting, to kill nematodes and other pests that can destroy crops like grapes and strawberries.
Late this September, the state’s scientific review panel meeting drew a crowd to Sacramento for a day and a half of hearings, during which the Department of Pesticide Regulation (DPR) presented its report on the pesticide’s health effects. Although the chairman, John Froines, professor of chemical toxicology at UCLA, admonished the audience that his charter was merely to critique the science behind the DPR’s report, not to approve or reject the chemical’s use, during the public comment period farmers and others spoke passionately for or against the controversial pesticide.
About fifty people spoke, with some growers arguing that they desperately needed the pesticide to replace methyl bromide, which two decades ago was scheduled to be phased out under the Montreal Protocol as an ozone-depleting gas. “We need all the tools possible to survive today,” said Will Scott of the African-American Farmers of Calfornia.
Arysta LifeScience Corporation, the chemical’s Tokyobased manufacturer, says that adopting methyl iodide may decrease environmental damage. Methyl iodide is slightly stronger, pound for pound, than methyl bromide, and Arysta estimates that using it instead could cut the pounds of pesticide applied by thirty to fifty percent.
It’s an argument that’s extremely seductive to farmers. Many loved methyl bromide because it was the ultimate kill-all chemical for all kinds of soil pests, and strawberries and other high-value crops grow and yield quickly after chemical soil sterilization. Indeed, the soil is so devoid of life after sterilization that lettuce producers rent fumigated fields two years later, because such soil is still likely to be free of the pests that plague leafy greens.
However, a 2007 letter signed by 54 scientists, including four Nobel laureates, pointed out the health hazards of using these powerful chemicals. “Alkylating agents like methyl iodide are extraordinarily well-known cancer hazards in the chemical community because of their ability to modify the chemist’s own DNA, as well as the target molecule in the flask, leading to mutations that are potentially very harmful,” reads the letter, addressed to administrator Stephen Johnson of the US Environmental Protection Agency.
“Because of this potential toxicity, chemists who work with this material use the smallest amounts possible and take great precautions to avoid exposure,” the letter continues. “Because of methyl iodide’s high volatility and water solubility, broad use of this chemical in agriculture will guarantee substantial releases to air, surface waters and groundwater, and will result in exposures for many people. In addition to the potential for increased cancer incidence, US EPA’s own evaluation of the chemical also indicates that methyl iodide causes thyroid toxicity, permanent neurological damage, and fetal losses in experimental animals.”
At the September hearing, the panel of eight health scientists heard technical testimony from the preparers of the DPR draft report, Arysta representatives, the US EPA, the California Rural Legal Assistance Foundation, and the Pesticide Action Network of North America. A scientific meeting, which preceded public comment, included discussion of groundwater contamination, fetal defects, nervous system toxicity, thyroid damage, cancer induced by genetic damage to DNA, and how big the safety factors for methyl iodide should be. These include determining buffer zones, application rates, and other considerations, although one panelist, Dr. Paul Blanc, argued that the evidence presented was sketchy enough that the term “safe level” was misleading, since so much about the chemical is still unknown.
Thomas McKone, an expert in air modeling and exposure assessment at the University of California at Berkeley, agreed, calling the data regarding chemical leaching “rather alarming, particularly since the uncertainties are large and we don’t know what a safe dose is.”
Theodore Slotkin, professor of neurodevelopmental toxicology at Duke University, stunned many in the audience when he said that he was “worried about late developing, irreversible brain damage,” which he said was not addressed adequately in the existing reports.
The report will be used in the DPR’s decision about whether to register the chemical for use and will also factor into whether the US EPA will reconsider its own decision to allow registration across the United States. Presently, each state is allowed to make its own decision, and California, Washington, and New York are the last holdouts against its use. If the EPA reverses its decision, the chemical would be banned across the nation.
The environmental movement has long been divided over the replacement of one of the world’s worst ozone depleters. Because of exemptions that substantially weakened the Montreal Protocol and kept extending the date for final phaseout, methyl bromide is still used at the rate of about ten million pounds per year in the United States alone. Worldwide, more than 42 million pounds were used in 2008. Since substantial ozone damage can take generations to heal, the chance to permanently squelch a chemical whose final phaseout date has been a moving target since 1991 is undeniably appealing.
It was only recently that the National Resources Defense Council publicly took a position against the use of methyl iodide, a development that many activists consider significant. The organization is determined to stop the dissemination of millions of pounds of methyl bromide, which is still being used at about a fifth of pre-Montreal levels, but not by exposing the environment to enormous amounts of methyl iodide. Many activists are acutely aware that there is only one difference between the limited success they’ve had banning methyl bromide versus the many failures to stop other chemicals: The whole world hates ozone-depleters. They fear that methyl iodide, which poses no ozone threat, will be applied with abandon throughout the state’s farms and nurseries, which generate about $25 billion of California’s annual revenues.
Susan Kegley, a senior scientific consultant for the Pesticide Action Network North America (PANNA), warns, “About the only thing to like about methyl iodide is that it’s not an ozone-depleter. Methyl iodide is just as toxic as methyl bromide, maybe more so, and in the laboratory, it must be handled as a dangerous chemical. Should we be applying thousands of tons of it to California farms?” Each year, says Kegley, California agriculture already uses between 30 and 35 million pounds of pesticides.
At stake is the health of anyone who comes into contact with the chemical, particularly in the Central Valley, where subdivisions have sprung up faster than weeds. Arysta’s label specifies quarter-mile buffer zones, but a drive through these communities reveals subdivision fences bordering strawberry fields. If approved, the chemical could be applied at a rate of up to 175 pounds per acre, including in California vineyards.
During the public comment period at the September hearing, Santa Cruz organic strawberry grower Jim Cochran of Swanton Berry Farm argued for organic strawberry production. “When I started growing strawberries organically a few years ago, I was one hundred percent of the organic growers,” he told the panel. “Now I grow about one to three percent. It is possible to grow them organically.” (About 87 percent of the nation’s estimated 525 million pounds of strawberries are grown in California.)
Some farm workers also said that they worried about the health effects of working in fumigated fields, but felt compelled to do so because their jobs are dependent upon the success of California crops, such as strawberries, that are frequently grown by fumigating crops under vast acreages of plastic tarps.
Horracio Ramirez, an agricultural worker who has planted crops by slitting holes in the plastic sheeting that covers fumigated fields, said through a translator, “Tarp removers have gotten sick from the chemicals we already have, and this will be even worse. Not all of us workers get the protection we need.”
“When we plant something, we punch holes in the plastic,” he continued. “[The pesticide] comes out when you open a hole. I told my foreman, but he said it was only soap.” Ramirez said that he doesn’t believe that he was only exposed to soap.
Julian Cruz, another field worker, said that dangerous chemicals are already in the strawberry fields. “Your eyes water all day long, and you get nosebleeds,” he said. “If this is a stronger chemical than what we have already, what will it be like for us if it’s approved?” Currently, chloropicrin, metam sodium, and methyl bromide are the most commonly used strawberry pesticides.
Enrique Hernandez, another agricultural worker, spoke of his dilemma: “I know that the chemical is dangerous, but people need to work.”
When Hernandez and others said that they used the protections that Arysta specifies, several panel members questioned them about what kind of masks they wore. “Were they white, black, or brown?” the doctors asked. Most of the workers answered that they were white, indicating that they were not respirators but throwaway masks like those used in paint shops, which are ineffective against fumigants.
Perhaps most surprising was that when the panel asked for details on the chemical’s underlying mechanism, nobody at the meeting—attended by Arysta representatives, agricultural experts, chemists, and even one of the chemical’s co-inventors—could explain how methyl iodide kills pests such as nematodes.
The panel’s consensus appeared to be that DPR had done an admirable first draft, but that additions to address groundwater contamination, safety margins, neurotoxicity, birth defects, and thyroid damage were necessary before the report could be issued in final form. The licensing decision is expected in 2010 or later. A representative from Washington state also spoke at the meeting, indicating that the state is watching the California fight closely. Whether Washington will continue to join New York in holding out against methyl iodide is still an open question. If the EPA were to reverse its decision on methyl iodide, the chemical would join a very short list of pesticides whose use was first approved but later banned.
Copies of the report, as well as other information on methyl iodide, can be found on the DPR’s Web site: www.cdpr.ca.gov
