Human exposure to etofenprox, (s)-methoprene, and piperonyl butoxide from dogs treated with Bio Spot DefenseRT

Currently, pyrethroids are more commonly used than any other class of ectoparasiticides on pets. Due to lack of safety data, pet owners have raised serious concerns for their use on dogs and cats. Concerns have also been raised about transferable residues of pesticides to the pet owners, veterinarians, veterinary technologists, and dog handlers. The present investigation was therefore undertaken with two specific objectives: (1) to determine the safety of Bio Spot Defense Flea and Tick Spot OnRTM applied to six dogs, and (2) to determine the residue of active ingredients of the product (etofenprox, s-methoprene, and piperonyl butoxide) in blood of dogs and gloves worn to pet dogs at 24, 48, 72 hours, and 1, 2, 3, 4, and 5 weeks post-application. At these time intervals, dogs were evaluated for physical examination. Residues of active ingredients were determined and confirmed using Gas Chromatograph/Mass Spectrometer (GC/MS). In the blood, etofenprox was detected as early as after 48 hours (18.4+/-5.1 ppm) and the residue persisted until 1 week (0.8+/-0.4 ppm). S-methoprene and piperonyl butoxide were not detected in the blood at any time. In the gloves, the highest concentrations of etofenprox, s-methoprene, and piperonyl butoxide were determined at 24 hours (9,552.0+/-1551.8; 2307.9+/-456.7; and 1286.1+/-0.5 ppm, respectively). Residues of all three compounds were detected in appreciable concentrations in the gloves until 1 week (294.9+/-27.2; 80.6+/-10.1; and 40.5+/-5.8 ppm, correspondingly). Of course, with a steep descending trend, residues of these compounds were present 5 weeks post-application. Findings of this investigation revealed: (1) none of the dogs exhibited any physical or behavioral abnormality, and (2) active ingredients of the product persisted on dog's coat for five weeks. The veterinarians, veterinary technologists, and dog handlers can be exposed to significant levels of etofenprox, s-methoprene, and piperonyl butoxide following chronic exposure and may suffer from cumulative effects, if not properly protected.