Exposure, Risk and Safety Information

Routes of Exposure and Potentially Exposed Populations
Occupational Exposure
Dietary Consumer Exposure

Routes of Exposure and Potentially Exposed Populations

Exposure to chlorpyrifos may occur as a result of ingestion, skin contact, or inhalation of vapor or spray mist. These exposures may be associated with occupational use of chlorpyrifos via activities associated with the manufacture or through its handling and use by professional pesticide applicators or farmers. Due to the wide variety of agricultural uses of chlorpyrifos, dietary ingestion of trace chlorpyrifos residues in food also represents a potential route of exposure for consumers. Information for all these routes of exposure has been generated. Completion of risk and safety assessments involves a comparison of the magnitude of exposure with some toxicological endpoint (e.g., No Observable Effect Level), usually with inclusion of a safety factor. For chlorpyrifos, toxicological endpoints have been set based on studies in both animals and humans.

Occupational Exposure

Agricultural Workers
Chlorpyrifos formulations may be applied to a myriad of agricultural crops by ground boom spray application, airblast application, aerial application, or soil incorporation. Studies have been conducted to assess exposures to mixer/loader operator, applicators and workers responsible for reentry into treated crops. All the agricultural worker scenarios tested have indicated that the No Observable Effect Level (NOEL) based on red blood cell acetylcholinesterase inhibition will not be exceeded when used according to the label.

Dietary Consumer Exposure

Use of chlorpyrifos products may result in the presence of trace residues in the harvested portions of various agricultural commodities for primary or secondary human consumption. Controlled field trials are conducted to determine maximum residue levels to which consumers may be exposed. For chlorpyrifos, more than 300 of these types of trials have been completed and the resulting database supports use of chlorpyrifos on more than 100 crops worldwide. In addition, actual market-basket data for residues present in agricultural products on supermarket shelves have been collected. This information indicates that actual dietary exposure levels are several orders of magnitude below those estimated from controlled residue trials.

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