For a conventionally-grown grain, reaching skyward through fogs of pesticides and sudden avalanches of fertilizer, harvest must loom as a moment of liberation, a rootless escape from industrial agriculture’s chemical fields.
That freedom doesn’t last far beyond the combine’s quick slice. Rising up ahead, there is the silo.
On non-organic farms, the silo is often a place for a final dusting of pesticides; and these chemical gusts add a new layer of residue to grains that will ultimately be milled, rolled, baked and packaged for the North American consumer.
According to an April report by The Organic Center: “In addition to containing more nutritionally wholesome whole food ingredients, organic bread also helps lower exposure to pesticides. Most conventional and ‘natural’ breads contain low levels of residues of one or two pesticides, most of which are used to control insects in grain storage bins.
“These residues translate into modest to moderate risks per serving of bread — risks well below the average risks associated with residues in a serving of fresh fruits or vegetables. Still, pesticide residues in grains and flour have been significant enough to trigger several actions in recent years by the pesticide industry and EPA to reduce dietary risk, particularly targeting high-risk insecticides like the organophosphate (OP) chlorpyrifos-methyl.
“This OP insecticide was the industry standard for years in controlling insects in storage bins with conventional grains. The EPA and manufacturers initiated steps to phase out its use in 2001. In the most recent wheat grain testing conducted by USDA (2005), OPs still accounted for 97% of overall risk in wheat grain.”
An earlier study appearing in Pure and Applied Chemistry (Holland et al.) found similar cause for concern: “Grains are frequently stored long term (3-36 months) at ambient temperatures in bulk silos where insecticides may be applied post-harvest to reduce losses from storage pests. Grain based foods therefore have the potential to be a major source of residues in the diet for these insecticides . . . Studies on grain following post-harvest treatments with insecticides have generally shown that residues only decline rather slowly.”
Complementary research out of Greece (Amvrazi, University of Thessaly) explained this slow dissipation of chemicals applied to grains in fields and silos: “The dissipation of pesticides is a slow process as compared with the cold storage of fruits and vegetables mainly due to pesticide retention on the seed coat and/or the high degree of pesticides penetration from the seed coat to the bran and germ which contain high levels of triglycerides.”