Dichlorvos (DDVP) Risk Characterization Document - California ...

Acute Exposure
Estimates of potential acute dietary exposure used the highest measured residue values at or below
the tolerance levels for each commodity except for the use of tolerance levels for meat products
(Table 17 and Appendix A). The following assumptions are used to estimate potential acute dietary
exposure from measured residues: (1) the residue does not change over time, (2) the concentration
of residue does not decrease when the RAC is washed or cooked, and (3) all foods that are
consumed will contain the highest reported residue.
Chronic Exposure
Estimates of potential average annual chronic dietary exposure used the mean of measured and
"below detection limit" residue values for each commodity. The default procedure assumed that
"below detection limit" residues were equal to one-half (50%) of the MDL for each commodity. The
following assumptions were used to estimate potential chronic dietary exposures from measured
residues: (1) the residue level does not change over time, (2) residue are not reduced by washing or
cooking, and (3) exposures to a commodity at all reported residue levels do occur, i.e. a commodity
with the average calculated residue is consumed every day at an average annual level (dosage). The
actual residue values used are presented in Table 17.
Lifetime Exposure
Estimate of potential lifetime dietary exposure used the result for the US general population from the
chronic dietary analysis.
Dietary Assessment
Dietary assessment of DDVP was conducted for acute, chronic, and lifetime exposures. Copies of the
exposure analyses are available upon request to the Medical Toxicology Branch.
Acute Exposure
Acute dietary exposure analyses were conducted using the Exposure-4 software program developed
by Technical Assessment Systems, Inc. (TAS). The Exposure-4 program estimates the distribution
of user-day (consumer-day) exposure for the overall U.S. population and specific population
subgroups (TAS, 1992a). A user-day is any day in which at least one food from the specific
commodity list is consumed. The consumption analysis uses individual food consumption data as
reported in the 1987-88 USDA Nationwide Food Consumption Survey (USDA, 1987-88).
Based on the 95th percentile of user-days exposures for all specific population subgroups, the
potential acute dietary exposure of DDVP from all labeled uses ranged from 0.50 to 1.65 ug/kg-day
(Table 18). Children (1-6 years old) had the highest potential acute dietary exposure (1.65 ug/kg-day)
to DDVP residues.
Chronic Exposure
The potential chronic dietary exposure was calculated using the Exposure-1 software program
developed by TAS, Inc. (TAS, 1992b). The food consumption data for the chronic analysis were also
based on the 1987-88 USDA Nationwide Food Consumption Survey (USDA, 1987-88). The program
estimates the average annual exposure for all members of a designated population subgroup. The
mean potential chronic dietary exposure for all population subgroups ranged from 0.06 to 0.53 ug/kgday
(Table 18). The population subgroup of children (1-6 years) had the highest potential exposure
(0.53 ug/kg-day). This level is 5,300-fold higher than the level (0.0001 ug/kg-day) estimated by the
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