Human Exposure to Imidacloprid from Dogs Treated with Advantage®

The objective of this investigation was twofold: (1) to determine the transferable residue of imidacloprid in gloves worn while petting experimental household dogs after the application of Advantage(R) and (2) to determine the imidacloprid residue in the dog's blood. Advantage(R) contains 9.1% imidacloprid, which controls fleas on dogs for up to 30 days. Imidacloprid produces toxicity by interacting with nicotinic receptors. Advantage(R) (364 mg imidacloprid/dog) was applied topically to six household dogs. The glove and blood samples were collected at 24 h, 72 h, and then on a weekly basis for 5 weeks post-Advantage(R) application. The glove samples were collected by petting each dog for 5 minutes while wearing a different glove per dog. The blood samples (5 mL from each dog) were collected into EDTA tubes. The imidacloprid residue was determined in the blood extracts and glove samples using RP-HPLC. The highest levels of imidacloprid residues were detected at the 24-h interval in both glove (254.16 +/- 25.49 ppm) and blood (54.06 +/- 3.00 ppb) samples. The blood imidacloprid residue was reduced by one third at the 72-h interval (18.73 +/- 2.00 ppb) and was not detected after 1 week. Imidacloprid residue in the glove samples decreased approximately one third between each collection interval. The residue of imidacloprid in the glove extract by the fourth week was very low (0.08 +/- 0.02 ppm) and not detected by the fifth week. The present findings suggest that following topical application of Advantage(R), imidacloprid residue can be detected in the dog's blood for up to 72 h, and transferable residue on the dog's coat can be detected for up to 4 weeks. Repeated chronic exposure to imidacloprid may pose possible health risks to veterinarians, veterinary technologists, dog caretakers, and owners.