Characterization of Risks Associated with the Use of Propoxur. R. C. Cochran, J. R. Sanborn, C. A. Aldous, and K. F. Pfeifer, Dept. of Pesticide Regulation, Calif. EPA, Sacramento, CA
(The opinions expressed in this paper represent the views of the authors and do not necessarily reflect the views and policies of the Department of Pesticide Regulation. The mention of trade names or commercial products does not constitute an endorsement or recommendation for use.)
Margins of Safety (MOSs) for mean acute occupational exposures, based on the 2-hour NOEL of 800 µg/kg for cholinergic signs in humans, ranged from 544 to 5,000. The MOSs for the 95th percentile of the absorbed cycle (2 hours) dosages ranged from 100 to 2,500. MOSs for potential chronic occupational exposure to propoxur ranged from 479 to 1,707. Maximum Likelihood Estimates (MLEs) of excess lifetime risks of cancer from occupational exposure to propoxur ranged from 1 x 10-6 to 6 x 10-6, based on a maximum likelihood estimate (MLE) for human cancer potency was 3 x 10-3 (mg/kg-day)-1. The upper-bound excess lifetime risks of cancer for theoretical occupational exposure to propoxur ranged from 2 x 10-6 to 9 x 10-6, based on an upper bound (95% confidence level) of 4 x 10-3 (mg/kg-day)-1. MOSs for mean acute non-occupational exposures ranged from 97 for pet owner/groomers to 3,636 for adolescents at home after the house had undergone crack and crevice treatment with propoxur. The MOS for the 95th percentile of the absorbed cycle dosage for dog owner/groomers was 13. The MOSs for potential chronic exposure to propoxur, based on the NOEL of 7,000 µg/kg for hemolytic anemia in dogs, ranged from 5,833 to 53,846, with children (ages 1-5 years) having the lowest MOS. None of the MLEs for excess lifetime risks of cancer from non-occupational exposures to propoxur exceeded 1 x 10-6. The upper-bound (95%) excess lifetime risks of cancer for theoretical non-occupational exposure to propoxur were not greater than 2 x 10-6.
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