Historical pesticide exposure in California using pesticide use reports and land-use surveys: an assessment of misclassification error and bias.

Abstract

We used California's Pesticide Use Report (PUR) and land-use survey data to conduct a simulation study evaluating the potential consequences of misclassifying residential exposure from proximity to agricultural pesticide application in health effect studies. We developed a geographic model linking the PUR with crop location data from land-use surveys to assess the impact of exposure misclassification from simpler exposure models based solely on PUR or land-use data. We simulated the random selection of population controls recruited into a hypothetical case-control study within an agricultural region. Using residential parcel data, we derived annual exposure prevalences, sensitivity, and specificity for five pesticides and relied on the PUR plus land-use model as the "gold standard." Based on these estimates, we calculated the attenuation of prespecified true odds ratios (ORs), assuming nondifferential exposure misclassification. True ORs were severely attenuated a) when residential exposure status was based on a larger geographic area yielding higher sensitivity but low specificity for exposure, in contrast to relying on a smaller area and increasing specificity; b) for less frequently applied pesticides; and c) with increasing mobility of residents among the study population. Considerable effect estimate attenuation also occurred when we used residential distance to crops as a proxy for pesticide exposure. Finally, exposure classifications based on annual instead of seasonal summaries of PUR resulted in highly attenuated ORs, especially during seasons when applications of specific pesticides were unlikely to occur. These results underscore the importance of increasing the spatiotemporal resolution of pesticide exposure models to minimize misclassification.

Aldehyde dehydrogenase inhibition as a pathogenic mechanism in Parkinson disease

“…Subject recruitment methods and case definition criteria have been described in detail (42). Pesticide exposure assessments were performed using a geographic information system-based computer model incorporating Pesticide Use Reporting forms that have been mandated by the California Department of Pesticide Regulation since 1974 and provide information on the location, date, and amount of pesticide in each commercial application (43,(48)(49)(50). Geocoded lifetime occupational and residential addresses were considered separately.…”

“…2A). We also quantitated the ALDH IC 50 values of benomyl and its metabolites using mitochondria isolated from rat liver (Fig. 2 B and D).…”

Using satellite derived land cover information for a multi-temporal study of self-reported recall of proximity to farmland

“…Whereas in 2001, agricultural land decreased to 50% of the study area. Even though many crops or orchards may enlarge, change location, or shrink during years between surveys (Rull and Ritz, 2003), a decrease of 5%-10% of agricultural land from 1978 to 2001 seems reasonable given the conversion of farmland to subdivisions in the suburban parts of the study area.…”

Downscaling Pesticide Use Data to the Crop Field Level in California Using Landsat Satellite Imagery: Paraquat Case Study

“…Although California maintains one of the most comprehensive pesticide use reporting systems in the world (California Pesticide Use Reporting (CPUR) system) [12], a major limitation of the data is that they are recorded at a coarse geographic scale of approximately 2.6 km 2 area ("Section" in the US Public Land Survey; approximately 1 mile by 1 mile) which is not adequate for residential-level exposure assessment [10,13,14]. The CPUR database is the primary source of information on where, when, and how pesticides are used in California.…”

“…Estimating pesticide use density near individual residences is usually calculated by taking a proportion of the total amount of a specific pesticide applied to crops within the entire Section [10,13] which has been found to result in substantial misclassification errors [13]. Improved estimates are possible by linking pesticide use to specific crop fields by incorporating land use maps developed by the California Department of Water Resources (CDWR) [10,11,13,15]. However, CDWR maps are produced only once every 7-10 years for a single county [16].…”