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

Fleas are a persistent problem for pets that require implementation of control measures. Consequently, pesticide use by homeowners for flea control is common and may increase pesticide exposure for adults and children. Fifty-five pet dogs (23 in study 1; 22 in study 2) of different breeds and weights were treated with over-the-counter flea collars containing tetrachlorvinphos (TCVP). During study 1, fur of treated dogs was monitored for transferable TCVP residues using cotton gloves to pet the dogs during 5-min rubbings post-collar application. Plasma cholinesterase (ChE) activity was also measured in treated dogs. Average amounts of TCVP transferred from the fur of the neck (rubbing over the collar) and from the back to gloves at 3 days post-collar application were 23,700+/-2100 and 260+/-50 microg/glove, respectively. No inhibition of plasma ChE was observed. During study 2, transferable TCVP residues to cotton gloves were monitored during 5-min rubbings post-collar application. Transferable residues were also monitored on cotton tee shirts worn by children and in the first morning urine samples obtained from adults and children. Average amounts of TCVP transferred to gloves at 5 days post-collar application from the neck (over the collar) and from the back were 22,400+/-2900 and 80+/-20 microg/glove, respectively. Tee shirts worn by children on days 7-11 contained 1.8+/-0.8 microg TCVP/g shirt. No significant differences were observed between adults and children in urinary 2,4,5-trichloromandelic acid (TCMA) levels; however, all TCMA residues (adults and children) were significantly greater than pretreatment concentrations (alpha=0.05). The lack of ChE inhibition in dogs and the low acute toxicity level of TCVP (rat oral LD(50) of 4-5 g/kg) strongly suggest that TCVP is rapidly detoxified and excreted and therefore poses a very low toxicological risk, despite these high residues.

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

Children can be exposed to pesticides from numerous residential sources such as carpet, house dust, toys and clothing from treated homes, and flea control remedies on pets. In the present studies, 48 pet dogs (24 in each of two studies) of different breeds and weights were treated with over-the-counter flea collars containing chlorpyrifos (CP), an organophosphorus insecticide. Transferable insecticide residues were quantified on cotton gloves used to rub the dogs for 5 min and on cotton tee shirts worn by a child (Study 2 only). First morning urine samples were also obtained from adults and children in both studies for metabolite (3,5,6-trichloro-2-pyridinol) quantification. Blood samples were obtained from treated dogs in Study 1 and plasma cholinesterase (ChE) activity was monitored. Transferable residues on gloves for all compounds were highest near the neck of the dogs and were lowest in areas most distant from the neck. Rubbing samples (over the collar) at two weeks post-collar application contained 447+/-57 microg CP/glove while samples from the fur of the back contained 8+/-2 microg CP/glove. In Study 2, cotton tee shirts worn by children at 15 days post-collar application for 4 h showed CP levels of 134+/-66 ng/g shirt. There were significant differences between adults and children in the levels of urinary metabolites with children generally having higher urinary levels of metabolites than adults (grand mean+/-SE; 11.6+/-1.1 and 7.9+/-0.74 ng/mg creatinine for children and adults, respectively, compared to 9.4+/-0.8 and 6.9+/-0.5 ng/mg creatinine before collar placement). Therefore, there was little evidence that the use of this flea collar contributed to enhanced CP exposure of either children or adults.

Effects of topical phosmet on fur residue and cholinesterase activity of dogs.

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).