acceptable pesticide use, they are inadequate as a guide to human health risks from
residues. Total Diet Studies have consistently shown that using MRLs as a basis for
calculating human dietary consumption of pesticides overestimates actual intakes by
one to three orders of magnitude. In addition, processing food for consumption can
lower perceived pesticide exposure and intake. A recommended approach to evaluat-
ing risks from pesticide residues in food includes allowances for losses in processing.
Processing treatments such as washing, peeling, canning, or cooking are important
factors leading to the reduction of pesticide residues left on crops. Most foods are
treated in some fashion before they are consumed. Processing can often substantially
reduce residue levels on or in food that has been treated with pesticides. For example,
a study tracking chlorothalonil on crops from field to table showed that normal han-
dling and processing of fresh cabbage, celery, cucumbers, and tomatoes led to large
reductions in residue levels.^32 The actual exposure of U.S. consumers to chlorothalo-
nil through diet was calculated at only 2 percent of the maximum theoretical level
estimated from MRLs. However, in some special cases, processing can cause more
toxic by-products or metabolites to form. Processing can also result in residues being
redistributed or concentrated in various parts of food.
Regulatory authorities are increasingly interested in such data. Studies into the
effects of storage and some commercial processing techniques on residues in food are
a part of the registration process for pesticides in many countries. Data on processing
are considered necessary to reassure consumers as to actual versus hypothetical expo-
sure to food residues.
Organophosphates
Organophosphates pesticides (OPs) frequently are applied to many of the foods im-
portant in children’s diets, and certain OP residues can be detected in small quantities.
When exposure to OPs is sufficiently high, as previously indicated, they interfere with
the proper functioning of the nervous system. There are approximately forty OPs, and
as a group they account for approximately half of the insecticide use in the United
States. The majority of OP use is on food crops, including corn, fruits, vegetables, and
nuts. In addition, OPs often have been used in and around the home. Examples of OP
pesticides include chlorpyrifos, azinphos methyl, methyl parathion, and phosmet.
Between 1994 and 2001, from 19 percent to 29 percent of food samples had de-
tectable OP residues. The highest detection rates were observed during 1996 and
1997, and the lowest rate was seen in 2001. Between 1993 and 2001, the amount of
OP pesticides used on foods most frequently consumed by children declined by
44 percent from 25 million pounds to 14 million pounds. In 1999 and 2000, the
EPA imposed new restrictions on the use of the OPs azinphos methyl, chlorpyrifos,
and methyl parathion on certain food crops and around the home, due largely to
concern about potential exposure to children.
Thirty-four OPs were sampled in each of these years. This measure is a surrogate
for children’s exposure to pesticides in foods. If the frequency of detectable levels of
Pesticides in Food | 89