Tracking California conducted a study to examine the use of agricultural pesticides near public schools in 15 agricultural counties in California for 2010.
The study yielded new information about the types and amounts of pesticides applied near public schools and identified disparities among children attending schools near the most pesticide use.
This information has been used to help guide policies, research, and other efforts to reduce potential pesticide exposures among schoolchildren. The results of this study are described in the report Agricultural Pesticide Use Near Public Schools in California.
California agriculture produces nearly half of all fruits and vegetables grown in the Unites States. These foods are essential components of a healthful diet and help promote public health here and throughout the country. However, agricultural production frequently relies on the application of pesticides that, under some circumstances, can be hazardous to human health. Compared with adults, children are more susceptible to the effects of pesticide exposure.
Because of the potential public health risks to children, we examined the use of selected agricultural pesticides near public schools in the top 15 counties by agricultural pesticide use in California for 2010. Our goals were to improve the methodology for the ongoing surveillance of agricultural pesticides to understand pesticide use patterns and provide information that can be used to assess and inform efforts to minimize potential pesticide exposures among schoolchildren.
For this study we estimated agricultural pesticide use near 2,511 public schools- attended by over 1.4 million students- in the 15 counties with the highest total reported agricultural pesticide use in 2010. We linked geographic school data to over 2.3 million pesticide use records using the following approach:
Step 1: Identify school boundaries The locations of school property boundaries were determined using GIS and satellite imagery. Once school boundaries were confirmed, a ¼ mile distance was drawn around each school boundary.
Step 2: Enhance pesticide application data Records of pesticide applications (from the Department of Pesticide Regulation's Pesticide Use Reports) were linked with other data, including field locations and crop information, to better pinpoint where the pesticides were applied. Eighty percent (80%) of PUR records were successfully matched to field-location data provided by county agricultural commissioners. The remaining PUR records were matched to fields based on Department of Water Resources land-use surveys (19% of PUR records). Only 1% of records could not be geographically enhanced beyond the square mile Public Land Survey Sections already reported in the PUR.
Step 3: Link pesticide application data with school boundary data The enhanced pesticide application data were then overlaid with the school boundary data to determine where pesticide applications likely occurred within ¼ mile of a school. After calculating how much of the field overlapped the area located within ¼ mile of the school boundary, area-weighted apportionment was used to estimate how much of a specific pesticide was used in the area of overlap for any given pesticide application. For example, if 10% of a field overlapped with the ¼-mile area around a school boundary, it was then estimated that 10% of the pesticides applied on that field was used within ¼ mile of the school. Using this information, the types and amounts of pesticides used within ¼ mile of a school were determined.
Caveats and Limitations: When apportioning pesticide use based on the area of overlap between the field and the ¼ mile area around the school, the study methodology assumed that pesticides were applied evenly across the entire field. There may be situations in which pesticides were unevenly or selectively applied, which could result in an overestimation or underestimation of the actual pounds applied within ¼ mile of a school. For example, if part of a field fell within ¼ mile of a school and if pesticides were not used on that portion of the field (e.g., in compliance with an existing regulation), this methodology would still assign some pesticide use to that portion.
Results are described in the report, executive summary, and FAQs. Key findings included:
This study assessed the presence of a potential health hazard (i.e., agricultural pesticides) near a vulnerable population. This information can help guide policies and other efforts to minimize pesticide exposures of schoolchildren and design future public health research. However, the presence of pesticide use near a school does not mean that exposure has occurred or that the health of any child or adult has been impacted.
Our report, subsequent community organizing and advocacy activities, and public input resulted in CDPR establishing new regulations to address pesticide use near schools and child day care facilities. Additionally, several school districts have subsequently adopted their own policies related to pesticide use near schools, citing our report.
Richardson MJ, Madrigal DS, Wilkie A, Wong M, Roberts E
This study was supported by the National Environmental Public Health Tracking Program of the Centers for Disease Control and Prevention (CDC), Cooperative Agreement Number 5U38EH000953-02. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the CDC, outside organizations, or external reviewers.