Strawberry Fields Forever


By Meghan Rosen

Earlier this year, California became one of 48 states to legally allow the sale and use of the fumigant pesticide methyl iodide. Methyl iodide is the proposed replacement for methyl bromide, a chemical widely used in California’s production of conventional strawberries. (If you’ve ever driven by fields with rows and rows of tightly stretched black tarps, you may have already seen the fumigation process at work: a few weeks before planting, methyl bromide is pumped into the soil and sealed in with thick plastic sheets. It’s colorless, odorless, and highly toxic; within days the gas can wipe out thriving populations of microorganisms, insects, and weeds — effectively sterilizing the soil.)

As the nation’s largest producer of strawberries (nearly 90% are grown in California), any decision to overhaul pest control is big, time-consuming, and subject to massive environmental and toxicological review. So, why the switch? According to the EPA, methyl bromide is a significant ozone depleting substance. In California, where nearly 40,000 acres are devoted solely to strawberry growth (only 4% is organic) and ~200 pounds of methyl bromide are applied per acre, the potential for environmental impact is huge. (The EPA estimates that 50-95% of the noxious gas escapes during fumigation or is released into the environment when the plastic tarps are removed.)

In 1988, the United States ratified the Montreal Protocol, an international treaty intended to curb use of ozone-depleting substances like methyl bromide. One goal was to completely phase out methyl bromide by 2005, with the exception of ‘critical use exemptions’ for farmers who absolutely depended on the chemical for pest control.

The U.S. applied for and won years of exemptions, but by 2007 methyl bromide use had dropped to 29% of 1991 levels. This same year, the EPA registered methyl iodide as a suitable alternative fumigant. The idea was simple: swap an ozone-depleting pesticide for its equally effective, ozone-friendly brother and everyone wins: conventional farmers can continue to harvest high-yield crops from fumigated soils, and the upper atmosphere is protected from harmful agricultural pesticides.

If only it were that easy. The EPA’s 2007 approval of methyl iodide came over loud protestations from scientists, environmental groups, and consumers. More than 50 chemists and physicians (5 of whom were Nobel Laureates) signed a letter urging the EPA to reconsider its decision. Chief among their concerns was the effect of methyl iodide on pregnant women, children, the elderly, and farm workers living near application sites; in lab animals, high exposure rates had been linked to thyroid cancer, neurological damage, and miscarriages.

That year, California’s Department of Pesticide Regulation (DPR) began its own extensive risk assessment of methyl iodide, and commissioned an independent scientific panel to review their data (more than a thousand pages total). In February 2010, the panel concluded that “any anticipated scenario for agriculture use would result in exposure to a large number of the public and… an adverse impact on public health.” Three months later, over these explicit objections from the review panel, the DPR proposed approval of methyl iodide for pesticide use in California.

In the two months following the announcement, 50,000 comments were filed with the DPR. Like the chemists and physicians who objected to the EPA’s decision in 2007, and the scientists on the review panel, most commenters were concerned with the health risks associated with exposure. Their concerns were legitimate. The DPR’s own risk assessment (which is posted on their website) found that “the application of methyl iodide in field fumigation … could result in significant health risks for workers and the general population.”

So, why did the DPR decide to move forward with the process of approving methyl iodide? Mary-Ann Warmerdam, the department’s director, responded last summer to criticism that the DPR was ignoring its own risk assessment in favor of economic interests.
She claimed that the DPR had considered both the scientific data, and the opinions of the review panel when deciding whether or not to approve methyl iodide and justified the decision by spelling out the difference between risk assessment and risk management. To put it bluntly, just because the DPR had concluded that methyl iodide was an exceptionally toxic, high-risk chemical didn’t mean they couldn’t use it.

But the news wasn’t all bad. Since methyl iodide is applied to the soil before planting, the EPA and DPR found little risk of pesticide residue on food crops. The gravest risk is borne by those who work with the chemical, or live near fumigated fields. In light of this, the DPR implemented a set of regulations that are the strictest in the country (and much tougher than existing federal guidelines).

For example, to use this fumigant pesticide in California, large buffer zones are required around fields. Schools, hospitals, and nursing homes must be surrounded by a half-mile of buffer (twice the distance required by the EPA). Workers must have special training, respiratory protection, and cannot reenter fields for two weeks after application (the EPA’s minimum time is 5-10 days).

But even with proper protection, minimal exposure is inevitable, and accidental overexposure is an undeniable risk. Is this the unavoidable cost of growing ozone-friendly strawberries? Is it fair to do a cost/benefit analysis of hazardous chemical use when the brunt of the cost is borne by low-income field workers? To many residents, the issue has merely shifted from environmental to human rights.