Continued use of sulfuryl fluoride sought

The American Seed Trade Association (ASTA) along with a coalition of other groups submitted comments to the U.S. Environmental Protection Agency (EPA) highlighting the importance of keeping sulfuryl fluoride as a viable means to control pests.

EPA's proposal eliminates any tolerances for grain found to have sulfuryl fluoride residue due to the threat posed to teeth and bones caused by aggregate exposure to fluoride.

"We understand the concerns behind this proposal, but the use of heat, a disinfestation method that EPA endorses, is not an effective pest control strategy for the seed industry," says Leslie Cahill, ASTA vice president of government affairs. "When seed is exposed to extreme heat, it along with the pests die."

Sulfuryl fluoride is one of only two fumigants the seed industry can use to control pests in seed conditioning plants and warehouses, as well as in packages of seed prior to shipment.

"Stored product pest control in seed is a critical process for our members, but other methods such as methyl bromide or heat treatments just aren't practical because of issues related to seed damage, human safety, environmental impact, cost and treatment time," Cahill explains.

Sulfuryl fluoride and cylinderized phosphine are used as fumigants to control insects in seed storage facilities; however, sulfuryl fluoride penetrates more quickly than cylinderized phosphine and controls all life stages of insect pests with no documented resistance; requires a shorter exposure time; and is non-corrosive and does not damage equipment, electronics or metal structures when properly used.

Cahill says that seed companies sometimes send excess seed and screenings from seed conditioning facilities to feedlots or elevators.

"Eliminating these tolerances will negatively affect the seed industry," Cahill says. "This means any corn, sorghum or other commodity exposed directly or indirectly to sulfuryl fluoride fumigation will have to be destroyed.

Companies routinely discard hundreds and thousands of bushels of corn seed each year that have been exposed to sulfuryl fluoride fumigants, but not treated with other pesticides or dyes, she says.

Cahill gives the example that one ASTA member annually discards 500,000 bushels of corn seed that has been exposed to sulfuryl fluoride. At $7 per bushel, the value of the discarded seed is $3.5 million per year.

"If that producer is not able to channel that product into the food/feed stream because of the eliminated tolerance, then that producer would incur an additional expense of $.60 per bushel or $300,000 per year just to get rid of the seed."

If EPA's proposal goes through and the tolerance is eliminated, the seed industry will be left with only one option for controlling insect pests in seed and seed storage structures - cylinderized phosphine.

"Should this happen, seed producers will incur slower fumigation cycles, delayed shipments and increased phytosanitary compliance challenges due to the likelihood of phosphine-resistant insects becoming more prevalent," Cahill says. "These challenges and burdens are more significant than any of the benefits accrued from eliminating fluoride residues in grain entering the food and feed chain."

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