The Pesticide Data Program
In the early 1990s surprisingly little was known about the frequency or levels of
pesticides in food as actually eaten. Then-existing government data on residues had
been collected as part of tolerance enforcement programs and represented residues at
the farm gate, prior to washing, shipping, storage, marketing, and preparation. Rela-
tively insensitive analytical methods were used. To improve the accuracy of pesticide
dietary risk assessments, in 1991 Congress funded a new USDA program, the Pesti-
cide Data Program (PDP). By design, the PDP focuses on the food consumed most
heavily by children. Food is tested, to the extent possible, ‘‘as eaten.’’ Banana and or-
ange samples are tested without their peels; processed foods are tested as they come
out of cans, jars, or freezer bags.^2
Pesticide Cause
A number of surveys indicate that pesticide treatments of food after it has been
harvested are more likely to leave residues than the treatment of crops during cultiva-
tion. Strawberries that need to be shipped over long distances may be treated after
harvest with fungicides to prevent fungi or molds. This could be one reason for the
higher-than-average frequency of violative residues on strawberries.
Detectable Pesticide Residues
Pesticides used to enhance food production are commonly separated into four dif-
ferent categories: herbicides, insecticides, parasitic worm killers, and fumigants. Some
pesticide-use estimates also account for chemicals such as sulfur and petroleum that
are registered as pesticides but produced mostly for other purposes. It is estimated
that, of the three major categories of pesticides, insecticides are generally the most
toxic, followed by herbicides and then fungicides. Parasitic worm killers are the least
toxic. These estimates are based on both chronic and acute toxicity scores.^3
The EPA is charged with establishing maximum allowable residue tolerances for
pesticides and the FDA monitors and regulates the U.S. food supply for compliance
with these tolerances. In addition, the PDP collects data on pesticide residues on
food. For example, foods sampled by the PDP from 1994 to 1998 showed the fol-
lowing trends: Single residue detections on sampled food commodities exhibited a
stable trend, ranging from 25 to 27 percent on sampled foods each year. Multiple res-
idue detections on sampled food commodities declined after an initial rise from
36 percent of sampled foods in 1994 to 29 percent in 1998. Overall, detectable residues
on sampled foods decreased from 61 percent in 1994 to 55 percent in 1998.^4
Data Characteristics and Limitations
PDP samples are collected by ten participating states, which represent all regions
of the country and half of the national population. Samples are collected near end
markets and large chain-store distribution centers.
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