Agricultural Pesticide Use in California: Pesticide Prioritization, Use Densities, and Population Distributions for a Childhood Cancer Study

Abstract

Several studies have suggested an association between childhood cancer and pesticide exposure. California leads the nation in agricultural pesticide use. A mandatory reporting system for all agricultural pesticide use in the state provides information on the active ingredient, amount used, and location. We calculated pesticide use density to quantify agricultural pesticide use in California block groups for a childhood cancer study. Pesticides with similar toxicologic properties (probable carcinogens, possible carcinogens, genotoxic compounds, and developmental or reproductive toxicants) were grouped together for this analysis. To prioritize pesticides, we weighted pesticide use by the carcinogenic and exposure potential of each compound. The topranking individual pesticides were propargite, methyl bromide, and trifluralin. We used a geographic information system to calculate pesticide use density in pounds per square mile of total land area for all United States census-block groups in the state. Most block groups (77%) averaged less than 1 pound per square mile of use for 1991-1994 for pesticides classified as probable human carcinogens. However, at the high end of use density (> 90th percentile), there were 493 block groups with more than 569 pounds per square mile. Approximately 170,000 children under 15 years of age were living in these block groups in 1990. The distribution of agricultural pesticide use and number of potentially exposed children suggests that pesticide use density would be of value for a study of childhood cancer.

Living near agricultural pesticide applications and the risk of adverse reproductive outcomes: a review of the literature

“…The resulting exposure estimates were limited by crop misclassification and the assumption that all fields were treated similarly for a given crop. 8 Rull et al 61 highlighted further limitations of landuse surveys and geocoded address data for assessing residential proximity to crops. These limitations include changes in land use between county survey years as a result of urban or suburban development expanding into rural areas and short-term market driven change in the production of crop types (e.g.…”

“…The PUR system also allows for evaluation of specific pesticide AI and the combination of pesticides with similar chemical or toxicological properties. 8 Use of the PUR, however, is not entirely without limitations. It does not, for example, take account of the drift and fate of pesticides in the environment (determined by factors including the pesticide persistence (i.e.…”

“…[1][2][3][4][5][6][7] There are a wide range of potential exposure pathways, including inhalation of ambient air, soil drift and persistence in household dust, potential groundwater contamination, parental occupational take-home exposures, recreation in fields, and eating produce directly from treated fields. 8 Researchers have detected pesticides in ambient air near agricultural fields in the US 9,10 with pesticide spraying applications resulting in drift for distances up to 1000 yards. [11][12][13][14] Several studies have shown that proximity of homes to crop fields sprayed with pesticides has strongly predicted higher exposure levels, 1,15 and acute pesticide poisonings have been reported in communities downwind of agricultural fields after pesticide applications.…”

Genotoxicity in native fish associated with agricultural runoff events

“…Those agricultural chemicals that may warrant further investigation are genotoxins (i.e., chemicals with at least two positive genotoxicity results, as summarized in [36]) applied at high rates in the Central Valley (Ͼ100,000 pounds of active ingredient per year in 2000; California Department of Pesticide Regulation Pesticide Use Database), such as captan, methyl bromide, and ziram (these chemicals were not analytes in the present study). Carbaryl, malathion, and trifluralin are also genotoxins applied at high rates in the Central Valley, but these were not detected at elevated concentrations in the present study [17].…”

Using Landsat satellite data to support pesticide exposure assessment in California

“…The ability to identify specific crop types grown near individual residences is a key element for improving the geographic scale of modeled pesticide exposure in California [26-28]. While the State of California maintains one of the most comprehensive pesticide use reporting databases in the world [21], the data is only recorded at a geographic scale of an approximately 2.6 km 2 polygon, or "Section" in the U.S. Public Land Survey, which may not be optimal for exposure assessment [4,28,29].…”