Fumigating the soil before planting pretty much kills any pests that might be in it. Unfortunately the fumigant tends to seep up through the soil and expose workers and others nearby. When the highly toxic fumigant methyl bromide was banned under the Montreal protocol as
a greenhouse gas an ozone depleting gas, growers started looking for a replacement. Now the EPA has approved one, methyl iodide. If you know any chemistry, you might suspect that replacing one halogen with another might not solve the problem. Indeed methyl iodide is nasty. If you want to use it you must employ a certified applicator, establish a buffer zone of 25 to 500 feet around the fields, no use within a quarter mile of a school, day care facility, nursing home, hospital, prison or playground. And if you are a shoveler, tractor driver or applicator you have to be trained and you have to wear a respirator. Farm workers can’t re-enter the fields for five days after application.
The EPA seems satisfied that these precautions will all be honored and are themselves sufficient. Not everyone agrees:
Despite the protests of more than 50 scientists, including five Nobel laureates in chemistry, the U.S. Environmental Protection Agency on Friday approved use of a new, highly toxic fumigant, mainly for strawberry fields.
The new pesticide, methyl iodide, is designed for growers, mainly in California and Florida, who need to replace methyl bromide, which has been banned under an international treaty because it damages the Earth’s ozone layer.
In a letter sent last month to EPA Administrator Stephen Johnson, 54 scientists, mostly chemists, warned that “pregnant women and the fetus, children, the elderly, farmworkers and other people living near application sites would be at serious risk.”
Methyl iodide is a neurotoxin and carcinogen that has caused thyroid tumors, neurological damage and miscarriages in lab animals.
But EPA officials said Friday that they carefully evaluated the risks and decided to approve its use for one year, imposing restrictions such as buffer zones to protect farmworkers and neighbors.
“We are confident that by conducting such a rigorous analysis and developing highly restrictive provisions governing its use, there will be no risks of concern,” EPA Assistant Administrator Jim Gulliford said in a letter sent Friday to the scientists. (LA Times)
One reason the chemists were so concerned is that they have first hand experienced with methyl iodide:
Many of the chemists — who use small amounts of methyl iodide in their laboratories to attach molecules and are careful to avoid exposure — said they are shocked that the EPA is allowing its use as a pesticide because it can drift into neighborhoods and pollute groundwater.
“It is potentially really toxic, and it’s certainly very reactive. From what we know about its chemistry, we know this stuff reacts with DNA. It mutates it. So it’s prudent to be as careful as you can with it,” [Robert Bergman, the Gerald E. K. Branch Distinguished Professor at UC Berkeley's chemistry department] said in an interview Friday.
Of course EPA has its own experts on methyl iodide:
The manufacturer, Arysta, has spent eight years and more than $11 million collecting toxicological and environmental data to persuade the EPA to register methyl iodide as a pesticide.
Arysta’s former chief executive, Elin Miller, is now a top official at the EPA and was appointed administrator of its northwest region last year.
It’s not clear how much methyl iodide will be in use because California, along with Florida the chief venue for its use on strawberry fields, has yet to license it and it says it will take its own sweet time in doing so. The restrictions are expensive, another disincentive for use. Finally, the EPA is overhauling its regulations for all fumigants, so they only licensed it for one year.
So what’s the hurry? Once licensed and in use it becomes harder to discontinue. In a year they can include it with all the other fumigants. Just in time to get it all done before the next administration. That’s the hurry.