Download the Technical Report with details on sampling and analysis (PDF, 2.8 Mb)
Executive Summary of the Technical Report
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This report presents the results of air monitoring in populated areas in the town of Lindsay in Tulare County, California for chlorpyrifos and its oxon degradation product. PANNA and El Quinto Sol (a community group based in Lindsay) sampled during the peak use period of June, July, and August in both 2004 and 2005. Monitoring was conducted to coincide with the summer use of chlorpyrifos as an insecticide on oranges for the control of lepidopterous pests and scale. |
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Chlorpyrifos is an organophosphorus insecticide that is neurotoxic to both insects and mammals, inhibiting acetyl cholinesterase, an enzyme necessary for proper transmission of nerve impulses. High levels of exposure to these types of pesticides can cause acute poisonings in highly exposed individuals. Low levels of exposure during fetal and infant development have been linked to developmental deficits of the nervous system.
The US Environmental Protection Agency (EPA) recently banned all residential uses of chlorpyrifos; however, agricultural use continues. Nationwide in 2001, US EPA estimated that 11-16 million pounds of chlorpyrifos were used, second only to malathion for US insecticide use.
Sample results from air monitoring in Lindsay, CA are reported in Tables 2 and 3 in the full report (download above). Of the 104 samples collected (spikes and blanks excluded) between July 13 and August 2 in 2004, 76% were found to be above the limit of quantitation (LOQ) of 30 nanograms (ng) of chlorpyrifos per sample (equivalent to an air concentration of 6 ng/m3 for a 24-hour sample). Eleven percent of the samples were above the 24-hour acute and sub-chronic child Reference Exposure Level (REL) of 170 ng/m3, calculated from the US Environmental Protection Agency’s inhalation No Observed Adverse Effect Level (NOAEL). The highest concentration observed for a 24-hour period was 1,340 ng/m3 (7.9 times the 24-hour acute child REL) at one of the sampling locations on July 16.
Of the 108 samples collected (spikes and blanks excluded) between June 13 and July 22 in 2005, 80% were found to be above the LOQ of 30 ng chlorpyrifos per sample (equivalent to an air concentration of 6 ng/m3 for a 24-hour sample). Twenty-three percent of the samples were above the 24-hour acute and sub-chronic child REL. The highest concentration observed for a 24-hour period in 2005 was 1,120 ng/m3 (6.6 times the 24-hour acute child REL) at one site on July 12.
We note that the California Department of Pesticide Regulation (DPR) has not incorporated the child protection factor of 10 in their determinations of “acceptable” levels of chlorpyrifos in air, a position that is contradictory to US EPA’s determination and one that has been disputed by the California Office of Environmental Health Hazard Assessment (OEHHA). The omission of this uncertainty factor allows exposures 10 times higher than the dose US EPA has determined to be health protective.
The chlorpyrifos oxon degradation product was not detected in any of the samples from 2004 or 2005.
Contact Information
If you would like more information about these results, please contact the Drift Catcher .
This page last updated December 5, 2006 .