Postharvest chemicals are in first group for review

There are few old or new postharvest chemicals.

By Geraldine Warner

Four commonly used postharvest chemicals are scheduled for a tolerance reassessment by the U.S. Environmental Protection Agency (EPA) by next year, although it is likely that the process will be delayed.

Tolerances of all registered agricultural chemicals must be reassessed as a result of the Food Quality Protection Act, passed by the U.S. Congress in 1996. All pesticides must meet a new health-based standard of "a reasonable certainty of no harm."

Risk will be based on cumulative exposure, which means that exposure to pesticides with similar modes of action will be considered together. The EPA will also take into account aggregate exposure, meaning exposure to an active ingredient from all sources--not just food.

An additional ten-fold safety factor may be applied for chemicals used on foods that are common in the diets of infants and children.

Because of these new regulations, it is likely that many chemicals used by the tree fruit industry will not meet the safety standards, Dr. Wally Ewart, the Northwest Horticultural Council's vice president of scientific affairs, reported at the Washington Tree Fruit Postharvest Conference. There are not many postharvest chemicals to begin with, and even fewer new ones in the pipeline.

"What I would like to say is that we have materials waiting in the wings to supplement those lost, but that's not the case," he said.

Some effective alternatives have already lost their postharvest registrations, such as Benlate (benomyl) and Rovral (iprodione), and there is little hope that they will be available again in the future. There may be some new biological controls, but these have yet to be proven effective. "Right now, it's a pretty bleak picture," he said.

The tolerances have been divided into three groups for assessment. The first group, which is scheduled to be completed by 1999, covers organophosphates, carbamates, and Class B1 and B2 carcinogens. These include the postharvest chemicals captan, DPA (diphenylamine), SOPP (Sodium ortho phenyl phenate), and TBZ (thiabendazole). Ewart said TBZ is in the same class of compounds as Benlate and DPA, and will be in the same "risk cup," so some of their uses may be lost.

The second group covers Class C carcinogens and pesticides subject to reregistration, which include ethoxyquin. Reassessment of these tolerances is scheduled to be completed by 2002.

The third group, which covers biological pesticides, includes the postharvest biocontrols Biosave (Pseudomonas syringae) and Aspire (Candida oleophila). Reassessment of this group is scheduled by 2005.

Ewart said it is unlikely the reassessments will be completed on time, and it may take the agency five to six years just to complete the first group.

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Postharvest chemicals are in first group for review

There are few old or new postharvest chemicals.

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