Cyphenothrin Flea and Tick Squeeze-On for Dogs: Evaluation of Potential Health Risks Based on the Results of Observational Biological Monitoring

Abstract

An observational biomonitoring study was conducted involving adults and children in households that purchased and applied a cyphenothrin-containing spot-on product for dogs as part of their normal pet care practices. The 3- to 6-yr-old children had greater exposure than the adult applicators in the same house, 3.8 and 0.6 μg/kg body weight, respectively. The mean measured values in children were 13-fold lower than those estimated using the U.S. Environmental Protection Agency (EPA) current standard operating procedures (SOP) for pet products (assuming 5% dermal absorption), although the maximum absorbed dosage of one child on one day was equivalent to the default value derived from the SOPs. With regard to potential human health risks, it can be concluded that despite the inherent conservatism in both the exposure and toxicology data, the margins of exposure (MOE) were consistently greater than 100 for average, 95th percentile, and maximum exposures. More specifically, the results of this study demonstrated that the MOE were consistently greater than 1,000 for mean exposures and exceeded 100 for 95th percentile and maximum measured exposures, which clearly indicates a reasonable certainty of no harm when using the cyphenothrin spot-on products. It is also noteworthy that Sergeant’s spot-on products containing cyphenothrin currently sold in the United States have lower weight percentages of active ingredient and lower applied amounts than those used by all but two of the participant households in this study.

Notes

¹ Studies now are being conducted in which gloved mannequin hands are used in simulated petting of the animals. These studies are not considered intentional human dosing studies and therefore do not require HSRB review. Data from mannequin studies are subject to the same limitations as that from other simulated petting studies.

² In any event, excluding household 026 would have had no practical effect on the analyses described herein.

³ However, if these seven samples had been treated as valid postapplication samples, the dilution of exposure would be minor.

Additional information

Funding

Funding for this study was provided by McLaughlin Gormley King Company and Sergeant’s Pet Care Products, Inc. Research Triangle Institute conducted the field phase of the study and Golden Pacific Laboratories conducted the analytical phase.