Biological monitoring use in refining the exposure assessment of agricultural operators.

OBJECTIVES

As part of the re-registration process for agriculturally active ingredients conducted by the United States Environmental Protection Agency (EPA), exposure and risk assessments are conducted for operators who mix, load, or apply agricultural products. The exposure assessment is typically based on a combination of data obtained from the Pesticide Handlers Exposure Database (PHED) and assumptions on various application parameters, such as application rates, hectares treated, and the like. However the exposure data from the PHED may not reflect current work practices for clothing as per the EPA worker protection standard and the improvements made in engineering controls for packaging, mixing-loading apparatus, and application methods. Thus the exposure assessments may overestimate the true exposure.

METHODS

This study consisted of 23 replicates of workers mixing, loading, or applying a formulation of ethoprop nematicide insecticide to potato fields as part of their normal work functions. The study was conducted at 13 separate sites in the south-central part of Washington State in the United States. Biomonitoring was conducted in which the urinary excretion of ethoprop and its principal metabolite was monitored on the day of exposure and for 3 days thereafter.

RESULTS

The exposure values estimated with the use of the PHED were approximately 26 to 51 times higher than the actual exposures determined in the study.

CONCLUSIONS

The monitored absorbed doses found in this study should be considered representative of the range of potential absorbed doses resulting from ethoprop use with engineering controls under the conditions of this study.