Independent variables in the models included the CPUR or CROP metrics, self-reported home and garden use of pesticides by pest treated (use in the preceding 12 months, yes or no), potential occupational pesticide exposure (anyone in the household employed during the preceding 12 months for each occupation, yes or no) and the year (continuous variable from 2001 to 2006, centered by subtracting 2000) and season of dust collection (winter = 1, spring = 2, summer = 3, and fall = 4).
2] (chlorthal-dimethyl) among residences classified as being within 1,250 m of agricultural use according to CPUR or CROP metrics (Table 2).
Distance from residence and days before dust collection 500 m Pesticide Metric 180 days 365 days 730 days Carbaryl CPUR 0.
a] Carbaryl CPUR 500 m 19 (21) 1,250 m 37 (42) 26 CROP 500 m 11(12) 47 1,250 m 24 (27) 30 Chlorpyrifos CPUR 500 m 68 (73) 47 1,250 m 77 (87) 47 CROP 500 m 48 (54) 1,250 m 70 (79) 51 Flea or tick 32 (36) 69 Farmworker or ranch worker 12(13) 100 Chlorthal-dimethyl CPUR 500 m 4 (5) 26 1.
In this study, chlorpyrifos, chlorthal-dirnethyl, tprodione, phosmet, and simazine concentrations were higher in residences with nearby agricultural pesticide use than in residences without nearby agricultural use as determined by the CPUR and CROP metrics.
In an earlier evaluation, we found that agreement between CPUR and CROP metrics differed depending on the spatial extent evaluated (Nuckols et al.
In a GIS, we linked the CPUR crop-specific pesticide use for each Section in the three study counties to the CDWR crop maps for the corresponding Sections.
For a small percentage of Sections where CDWR indicated crops but there was no reported pesticide use in CPUR, we assumed no pesticide use on those crops.
We also computed a CPUR metric (Figure 2B) as follows:
We also calculated specificity of the CPUR metric compared with the CDWR metric as a gold standard (percent of homes classified as unexposed by CDWR metric that were classified as unexposed by CPUR).
To examine the effect of classifying exposure using CPUR without crop maps, we categorized residential exposure predicted by the CPUR metric into quartiles, and then compared what proportion of residences fell into those categories using the CDWR metric.
For any pesticide use within the 500-m buffer, the specificity of the CPUR metric ranged from 86% for propargite to 96% for dicofol (Table 3).