Quantitative examination of major pathways and routes of exposure to pesticides is essential for determining human risk. The current study was conducted in two apartments and examines the accumulation of the pesticide chlorpyrifos in childrens' toys after the time suggested for reentry after application. It has been established for the first time that a semivolatile pesticide will accumulate on and in toys and other sorbant surfaces in a home via a two-phase physical process that continues for at least 2 weeks postapplication. A summation of the above for a 3-6-year-old child yielded an estimated nondietary total dose of 208 microg/kg/day. Potential exposure from the inhalation pathway was negligible, while dermal and nondietary oral doses from playing with toys contributed to 39 and 61% of the total dose, respectively. If children with high frequency mouthing behavior are considered as candidates for acute exposure to chlorpyrifos residues, the estimated acute dose could be as high as 356 microg/kg/day. Routine reapplication of pesticides could lead to continued accumulation in toys and other sorbant surfaces, e.g., pillows, with large sorbant reservoirs, which can become a long-term source of exposure to a child. Estimates of a child's nondietary exposure to chlorpyrifos associated with toys and other sorbant surfaces for a period of 1 week following application appear to be of public health concern, and studies of actual childhood exposure from this pathway are warranted in the home environment. The above information should be used to determine if current procedures for postapplication reentry are sufficient and to evaluate the need for procedures to store frequently used household toys, pillows, and other sorbant objects during insecticidal application.ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6

The National Human Exposure Assessment Survey ( NHEXAS ) / Minnesota Children's Pesticide Exposure Study ( MNCPES ) was a population -based study designed to characterize children's exposure to residential pesticides and to evaluate the contribution of residential and children's activities to children's exposure. Families of 168 children were surveyed for residential use of pesticides and children's activities. From these homes, families of 102 children between the ages of 3 and 13 years participated in a week -long intensive exposure study. Of the 102 children, 19 children were videotaped for four consecutive hours in their normal daily activities. The survey responses indicated that the youngest children were more likely to exhibit behaviors that would foster exposure to environmental contaminants. Comparison of questionnaire responses indicated that the videotaped subsample was representative of the exposure study population. The microactivities of the videotaped children that might contribute to their exposure via ingestion or dermal routes were quantified. Hand -tomouth and object -to -mouth activities were observed most frequently among the youngest children. The youngest children were also most likely to be barefoot both indoors and outside. Gender differences were found in mouthing behavior and the proportion of observed time spent outdoors.

No abstract

During the Minnesota Children's Pesticide Exposure Study ( MNCPES ) , comparisons were made between the insecticide / herbicide loadings obtained with two household dust / insecticide or herbicide samplers: the Edwards and Lioy ( EL ) press sampler ( used for dust collection from carpets or other surfaces ) and the Lioy, Wainman and Weisel ( LWW ) surface wipe sampler. The results were compared with hand rinse levels, and urine metabolite levels obtained from 102 children ( ages 3 ± 13 ) . All measurements were made during a 1 -week sampling period, and information was obtained on household pesticide use and each child's activities. Of the homes, < 5% had recent spot uses of a pesticide but none had recent general applications. The analyses focused primarily on atrazine ( a herbicide ) , and malathion, diazinon, and chlorpyrifos ( insecticides ) . Metabolites were measured for atrazine, malathion and chlorpyrifos. The atrazine levels obtained using the EL indicate that this compound was transported into the home by an unquantified transport mechanism ( e.g. tracking of soil ) . Two malathion hand rinse values exceeded > 170 ng / cm 2 , suggesting that since indoor surface levels were low, these children had other sources of exposure. Atrazine, chlorpyrifos and malathion were detectable in > 30% of the homes by the EL, LWW or hand rinse. Only chlorpyrifos had detectable levels in !50% of the samples for all types, i.e. compound or metabolite, which is consistent with it being a common household pesticide. The median ( and maximum ) chlorpyrifos levels for the EL surface, EL carpet, LWW surface ( two rooms ) , hand rinse, and urine metabolites were: 0.07 ( 32.6 ) ng / cm 2 ; 0.07 ( 44.5 ) ng / cm 2 ; 0.34 ( 3.64 ) ng / cm 2 ; 0.42 ( 14.4 ) ng / cm 2 ; 0.03 ( 2.14 ) ng / hand and 6.9 ( 59.0 ) g / g, respectively. A strong correlation was found for chlorpyrifos between the EL surface and carpet samples. Chlorpyrifos levels detected by LWW had a different distribution and concentration range than the EL, indicating that it collected more than the surface dislodgeable insecticide. EL was directly comparable to the hand rinse or urine levels, but only the LWW had a weak correlation with hand rinse levels, suggesting that the children had other sources of chlorpyrifos exposure. Thus, mechanistic exposure studies are needed to more accurately establish exposure ± dose relationships in residential settings.