An environmental measurement and correlation study of nondietary ingestion of pesticides was carried out in a colonia in south Texas. The purpose of the study was to evaluate young children's exposure to environmental levels of organophosphate ( OP ) pesticides in the household. Samples were collected to measure levels of OP pesticides in housedust and on children's hands. These, in turn, were compared to levels of OP pesticide metabolites in urine. A total of 52 children, 25 boys and 27 girls, participated in the spring and summer of 2000. The children were 7 -53 months of age at the time of recruitment. Univariate and multivariate regression analyses were carried out using SAS statistical software. Seventy -six percent of housedust samples and 50% of hand rinse samples contained OP pesticides. All urine samples had at least one metabolite and over 95% had at least two metabolites above the limit of detection ( LOD ). Total OP loadings in the housedust ranged from nondetectable ( nd ) to 78.03 nmol / 100 cm 2 ( mean = 0.15 nmol / 100 cm 2 ; median = 0.07 nmol / 100 cm 2 ); total OP loadings on the children's hands ranged from nd to 13.40 nmol / 100 cm 2 ( mean = 1.21 nmol / 100 cm 2 ; median = 1.41 nmol / 100 cm 2 ), and creatinine corrected urinary levels ( nmol / mol creatinine ) of total OP metabolites ranged from 3.2 to 257 nmol / mol creatinine ( mean = 42.6; median 27.4 nmol / mol creatinine ). Urinary metabolites were inversely associated with the age of the child ( in months ) with the parameter estimate ( pe ) = À 2.11, P= 0.0070, and 95% confidence interval À 3.60 to À 0.61. The multivariate analysis observed a weak association between concentrations of OP pesticides in housedust, loadings in housedust, and concentration on hands, hand surface area, and urinary levels of OP metabolites. However, hand loadings of OP pesticides were more strongly associated ( r 2 = 0.28; P= 0.0156 ) with urinary levels of OP metabolites ( pe = 6.39; 95% CI 0.98 -11.80 ). This study's preliminary findings suggest that surface loadings of pesticides, on hands, are more highly correlated with urinary bioassays and, therefore, may be more useful for estimation of exposure in epidemiologic studies than levels of pesticides in housedust.

c TDI-Brooks International, College Station, TX, USA An environmental measurement and correlation study of infant and toddler exposure to pesticides was carried out in a colonia south of the city of Laredo, Texas. As part of the study, homes were visited during the late spring or summer, and during the winter of 2000-2001. At each visit, families reported on their use of pesticides in and around the home and floor wipe samples were collected and analyzed for 14 organophosphate and triazine pesticides. Selection of homes was based on the presence of infants and toddlers. A total of 27 homes participated in both seasonal visits. The interval between visits was 671.4 months. Univariate and multivariate nonparametric analyses were carried out using SPSS s statistical software. Pesticide use within the home was more often reported than outside use and showed seasonal variation in use patterns. Indoor use was primarily associated with ants and cockroaches, and secondarily with rodents. The primary room treated was the kitchen, and the primary structures treated were the floors, lower walls, and dish cupboards. Seasonal variations were not found in the use of pesticides used outside the home and outdoor use was primarily associated with ant control. Based on parent reports, most pesticides used in the homes were pyrethroids. Several of the pesticides measured in floor wipe samples, Azinphos methyl, Fonofos, and Simazine, also showed seasonal variations. However, these pesticides are used in agriculture and were not associated with reported house and yard use patterns.

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