Levels of Aggregation

The Dietary Risk Index (DRI) can be applied at several levels of aggregation. The most detailed level quantifies relative dietary risks associated with the residues of a single pesticide, or its metabolites and/or isomers, in a specific food over one-year of Pesticide Data Program (PDP) testing.

Aggregate Dietary Risk Index – Means (DRI-M) and Food-Safety Dietary Risk Indexes (FS-DRI) for a specific food can be calculated by adding together the DRI-M and FS-DRI for each pesticide, metabolite, and isomer found in that found during an annual cycle of PDP testing. These aggregate DRI values are reliable estimates of average, total pesticide risk in any given food in the PDP program, since the EPA and USDA have worked together to assure that all possibly high-risk pesticides likely to result in detectable residues in food as eaten are included in PDP testing.

The same can be done for specific pesticides. Aggregate pesticide DRI-M and FS-DRI values can be computed by simply adding together the DRI-M and FS-DRI values across all foods in which a given pesticide was found by the PDP in a given year. In the case of pesticide DRI-M and FS-DRI values, these are not reliable estimates of overall annual dietary exposure to specific pesticides, because the PDP only tests around 25 foods each year.
DRI-M and FS-DRI values can also be added together across types of foods – fresh fruits or grains, for example – producing estimates of total DRI-M or FS-DRI values for food groups, based on the foods within each group that were tested by PDP in a given year.

Likewise, the aggregate DRI-M and FS-DRI values for all pesticides in a family of chemistry – organophosphate insecticides (in the menu select “Organophosphates” instead of “All Pesticides”) for example – can be calculated by adding together all DRIs for each pesticide within a family of chemistry.

Last, all aggregate DRI-Ms and FS-DRIs across all foods tested in a year can be added together. The sum represents the total dietary risk pool reflected by the foods tested by PDP in a given year and the residues found in the samples tested. These total DRI values across all foods tested are valuable in assessing the relative shares of risk accounted for by:

  • Specific pesticides,
  • Pesticide families of chemistry,
  • Types of food (fresh fruits, fresh vegetables, processed foods, juices, milk, etc),
  • Domestically grown food,
  • All imported food, as well as imports by country, and
  • Conventionally grown food versus organic food.