
USDA Seeks Alternatives to Methyl Bromide
for Quarantine SecurityBy Doris
Stanley February 20, 1997Every day, goods from around the world flow to the United States
borders. Like other countries, the United States tries to protect the
nations crops from pests that might hitch a ride into this country on the
incoming goods. As part of the protection effort, the
U.S. Department of Agriculture inspects all
incoming plants, plant products and other regulated articles. Since World War II, USDA has required that commodity treatments for
quarantine pests, especially fruit flies, meet or exceed a statistical standard
called Probit 9. This standard says treatments must kill or sterilize 99.9968
percent of the pests in a test of at least 100,000 individual pests. Treatments with heat, cold and irradiation have been used, but fumigation
with methyl bromide has been the most practical option for many commodities.
The more basic problem now: Methyl bromide has been identified as an ozone
depletor and is scheduled to be banned in 2001. Scientists with USDAs Agricultural
Research Service are working with the departments
Animal and Plant Health Inspection
Service to come up with a less rigorous standard than Probit 9 that might
be more appropriate for certain low-risk commodities. Probit 9 was adopted as a one-size-fits-all standard to provide adequate
quarantine security for the highest-risk commodities. While this standard has a
long history of usefulness, it may now be overly severe for commodities that
are rarely or minimally infested and that have a very low probability of
carrying exotic pests. USDA scientists suggest that the severity of the treatment be tailored to
the level of risk posed by the commodity. This would allow expanded use of
controlled atmospheres and other treatments that previously have not met Probit
9 requirements. Risk might be based on rate of pest infestation, pest survival
and reproductive capacity and the effects of harvest, processing and
distribution on the pests ability to survive and establish itself.
Although packaging, shipping conditions or season of shipment arent
considered in commodity quarantine under Probit 9, theyre important in
determining the risk a particular commodity presents to the importing country. Other approaches being considered in lieu of methyl bromide are discussed in
the January
1997 issue of Methyl Bromide Alternatives newsletter. The newsletter can be
accessed on the World Wide Web at: http://www.ars.usda.gov/is/np/mba/mebrhp.htm Scientific contact: Kenneth W. Vick, USDA-ARS
National Program Staff,
Beltsville, Md., phone (301) 504-5321 U.S. Department of Agriculture | |