Chemical fumigants are a staple of the industrial-food system. They’re used to sterilize soil before planting large monocrops, and also to control pests in stored food like grain and dried fruit. The building industry, too, uses them, mainly to fight termites. In the past, fumigants have caused much environmental damage, and tend to be quite toxic for humans, too. Now comes news that the building industry’s new favorite fumigant — sulfuryl fluoride — is a greenhouse gas 4,800 times more potent than carbon dioxide, according to a recent MIT study.

In a 2007 Victual Reality column, I told the story about the industry’s favorite fumigant, methyl bromide, was such an aggressive ozone destroyer that the world’s governments banned it in the 1987 Montreal Protocol. In the 22-plus years since, the U.S. government has undertaken a painfully slow phaseout of methyl bromide. It still hasn’t completely eliminated the rogue chemical.

As I reported in the Victual Reality column, in 2007 the EPA approved use of methyl iodide — a substance so carcinogenic that scientists use it to induce cancer in tissue cultures — as a replacement on farm fields. Who can care about farmworkers’ lives, when with the future of cardboard strawberries at stake? The EPA’s decision stunned the scientific community — 54 scientists, including two Nobel Laureate chemists, signed a letter strongly urging the EPA to reject methyl iodide on public-health grounds.

Methyl iodide is such scary stuff that it has yet to catch on. Two states — New York and California (potentially its biggest market) currently aren’t allowing its use despite the EPA’s green light. Even Florida — a state whose elected officials generally reside in the pocket of Big Ag — refused to accept the EPA’s decision completely. It registered methyl iodide with additional restrictions, Pesticide Action Network reports.

Enter sulfuryl fluoride, which the EPA approved of back in 2003. The EPA hasn’t registered it for use as a pre-planting fumigant; but it is widely used as a structural pesticide. How bad is it? Here’s MIT researcher Ron Prinn:

Our analysis has shown that the lifetime is about 36 years, or eight times greater than previously thought, with the ocean being its dominant sink …ton for ton, it is about 4,800 times more potent a heat-trapping gas than carbon dioxide.

Speaking in bland science-speak, he adds: it would become “a greenhouse gas of some importance if the quantity of its use grows as people expect.”


Update [2009-3-14 16:17:10 by Tom Philpott]: The original version of this post, titled “Strawberry Surprise,” contained errors that I regret. I had mistakenly read the linked account of an MIT study to mean that sulfuryl fluoride was registered for use by the EPA as a pre-planting fumigant for strawberries. Actually, the chemical is registered only for post-harvest use on food, as well as a structural fumigant for termites. I also reversed the phrases “methyl bromide” and “methyl iodide” on two occasions. Again, I regret these errors.