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

Dietary Exposure
DPR evaluates the risk of exposure of an active ingredient in the diet using separate processes: (1)
risk is determined for total exposure based on detected residue levels, and (2) risk is determined for
exposure to an individual commodity at the tolerance level (VI. TOLERANCE ASSESSMENT). For the
evaluation of risk from residues, the total exposure in the diet is determined for all label-approved
crops (raw agricultural commodities) and their processed forms as well as any secondary residues in
animal tissues. The degradation products and/or metabolites of the active ingredient which have
established tolerances or whose toxicity is of concern are also considered in the assessment.
Chronic dietary exposure estimates calculated by DPR were compared to those determined by
USEPA (Schaible 1994 and 1995). These estimates were considered because residue values used
by USEPA were adjusted for percent of crop treatment and reduction due to processing; thus, they
represented a more realistic estimate of dietary exposure compared to those by DPR.
Residue Data - general
The sources of residue data include surveillance programs conducted by the DPR and federal
agencies, field trials, and survey studies by registrants. Residue data obtained from the monitoring
programs are preferred for human dietary assessments since they are a more realistic estimate of
potential exposure. When residues are at levels higher than established tolerances, they are not
utilized in the dietary exposure assessments because incidents are investigated by the DPR Pesticide
Enforcement Branch and are relatively infrequent (consistently less than 1 per cent incidence
according to the DPR residue monitoring programs). DPR evaluates the potential risk of overtolerance
samples under a separate process referred to as an expedited acute risk assessment. In
the absence of any measured residues, the DPR dietary exposure assessments utilize surrogate data
from the same crop group as defined by USEPA or theoretical residues equal to USEPA tolerances.
There are two elements in the DPR residue testing program which are currently used for dietary
exposure assessment: Marketplace Surveillance and Priority Pesticide. Marketplace Surveillance is
designed to ensure that the pesticides are used according to the California laws and regulations.
Sampling in this program is weighted toward such factors as patterns of pesticide use, relative number
and volume of pesticides typically used to produce a commodity, relative dietary importance of the
commodity, past monitoring results, and extent of local pesticide use. Priority Pesticide was instituted
to target commodities known to have been treated with pesticides of toxicological concern.
The U. S. Food and Drug Administration (FDA) has three monitoring programs for determining
residues in food: (1) regulatory monitoring, (2) total diet study, and (3) incidence/level monitoring.
Depending on the program, raw agricultural commodities and/or processed foods are collected for
analysis. For regulatory monitoring, surveillance samples are collected from individual lots of
domestic and imported foods at the source of production or at the wholesale level. In contrast to the
regulatory monitoring program, the total diet study monitors residue levels in foods in forms ready for
consumption (Gunderson, 1988). The consumption patterns of 8 population subgroups are based on
the USDA 1977-1978 Nationwide Food Consumption Survey and the 1976-1980 National Center for
Health Statistics' Second National Health and Nutrition Examination. From these surveys, 234 food
items were selected to represent the 5,000 foods identified. The individual food and necessary recipe
ingredient items were collected from 4 broad geographic areas each year. The food items, after
preparation, were analyzed by multi-residue analytical methods. The incidence/level monitoring
program is designed to address specific concerns about pesticide residues in particular foods.
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