Effects of Topical Phosmet on Fur Residue and Cholinesterase Activity of Dogs

Abstract

Fleas, ticks, and mites are a major problem in many areas of the country for pet owners, and one treatment option involves the use of dips that contain pesticides. In the present study, dogs were dipped with a commercial phosmet (Imidan(R)) flea dip using the recommended guidelines for four consecutive treatments to determine the residues available for transfer to humans from the fur of the dogs. Twenty-four dogs of various breeds and weights were dipped, and each animal's fur was sampled with cotton gloves by petting for 5 minutes in a 10'' x 4'' area along the upper back before dipping and at 4 hours, and 1, 3, 7, and 14 days after dipping. Over the 4 dippings the 4-hour samples had a geometric mean of 2653 mug, and the 1-, 3-, 7-, and 14- day samples had geometric means of 877, 316, 84, and 20 mug, respectively. The samples ranged (in mug) from 80 to 16,794 at 4 hours, 44 to 7028 at 1 day, 1 to 4897 at 3 days, 1 to 2691 at 7 days, and 0.3 to 835 at 14 days. The residues removed by the petting did increase with the subsequent dips, but this was probably due to handler experience. The increase is not attributed to accumulation since there was less than 2% of transferable residue on the dog at 14 days post application. There was no significant inhibition of the plasma cholinesterase in the dogs over the study, suggesting that there was either a very low level of dermal absorption of phosmet or there was rapid detoxication (supported by EPA R 825170-01-0).

Assessing transferable residues from intermittent exposure to flea control collars containing the organophosphate insecticide chlorpyrifos

“…Previous reproducibility tests performed in our laboratory have shown that the decrease in CP residues on gloves with time is a result of decline by degradation or wear and is not the result of removal by the sampling procedures (Boone et al, 2001(Boone et al, , 2006. These data show that the use of cotton gloves and tee shirts for monitoring transferable residues yields reproducible results and that they do not remove appreciable amounts of the insecticide available for exposure.…”

“…Potential exposure has been reported from pets tracking residues into a home after diazinon application to a lawn (Morgan et al, 2001). Our laboratories have also reported transferable residues of CP and phosmet from the fur of pets following an insecticide dip (Boone et al, 2001(Boone et al, , 2006.…”

Assessing intermittent pesticide exposure from flea control collars containing the organophosphorus insecticide tetrachlorvinphos

“…Pesticide exposures to infants and children from food, water, and residential sources have been well documented (Woody, 1984;Zwiener and Ginsburg, 1988;Fenske et al, 1990;Morgan et al, 2001;Castorina et al, 2003;Colt et al, 2003;Rohrer et al, 2003;Hore et al, 2005;Boone et al, 2006;Chambers et al, 2007). However, one area that does not seem to have been appreciably explored is the possibility that residues of insecticides remaining on pet fur from flea control treatments could be a significant source of pesticide exposure in children.…”

Pilot biomonitoring of adults and children following use of chlorpyrifos shampoo and flea collars on dogs

“…Residues accumulated on gloves dissipated from 971 µg chlorpyrifos at 4h to 26 µg after three weeks. Boone et al [21] later conducted similar dog dipping studies with phosmet. Experimental differences in transferable residue levels were attributed to fur saturation of the dogs during dipping and rubbing pressure among the samplers.…”

“…In either case, the commercial dipping using these organophosphorous insecticides was not associated with substantial exposure (indicated by anticholinesterase activity). The amounts of organophosphorous insecticides applied during commercial dipping [1,21,22] were likely much greater than applications made by participants in our present pilot studies in which the dogs were treated by pet owners at their private residences using over-the-counter products.…”