California pesticide levels show low health risks

Department of Pesticide Regulation Director Brian R. Leahy announced that air monitoring of nearly three dozen pesticides in California for the past year shows residues well below levels established to protect human health and the environment.

"We’re pleased the results indicate a low health risk to residents of the communities where monitoring stations are located,” Leahy said.

"This information is essential to help us evaluate whether our restrictions on pesticide applications are protective over the long term.”

Only one of the chemicals exceeded its screening level for exposure periods of one year or less. That chemical, acrolein, is sometimes used as a pesticide, but the residues detected were most likely from motor vehicle and industrial emissions.

DPR established the air monitoring network in February 2011 in Shafter in Kern County, Salinas in Monterey County and Ripon in San Joaquin County. Results released today also include methyl bromide residues monitored by Air Resources Board stations in Oxnard in Ventura County and Santa Maria in Santa Barbara County at DPR’s request.

Thirty-four pesticides and five pesticide breakdown products were monitored, including six fumigants and 11 organophosphates. Twenty-nine of the chemicals were detected in at least one sample and 10 were not detected. DPR selected these pesticides based on the amount of use and their potential health risks.

"Detecting pesticides in communities surrounded by farmland is not a surprise,” Leahy emphasized. “California is the only state that monitors air as part of its continuous reevaluation of pesticides to ensure the protection of workers, public health and the environment.”

The air monitoring network, the first of its kind in the nation, was established to expand DPR’s knowledge of the potential health risks of long-term exposure to pesticides. DPR scientists sought more accurate estimates of health risks based on long-term exposure rather than extrapolation from short-term monitoring data to help them determine if additional protective measures are needed.

Shafter, Salinas and Ripon were selected from a list of 226 communities based on pesticide use on surrounding farmland and demographics, including percentage of children, the elderly and farm workers.

Santa Maria and Oxnard are areas with high use of methyl bromide and other fumigant pesticides.

The network is a follow-up to DPR’s groundbreaking pilot projects in Parlier in Fresno County in 2006 and Lompoc in Santa Barbara County in 2000, which lasted 12 months and 10 weeks, respectively.

DPR is using these data to compare pesticide concentrations with screening levels developed by its scientists, track trends in air concentrations and correlate concentrations with use and weather patterns. DPR set the screening levels in the absence of federal or state enforceable health-based limits on pesticide emissions in air.

Although not regulatory standards, the screening levels are guideposts for preliminary evaluations of air monitoring data.

State law requires DPR to continuously evaluate pesticides after they are in use. As part of this process, DPR conducts field studies to monitor exposure to workers and to measure how pesticides move and break down in air, soil and water. DPR uses this information to decide if further regulatory measures are necessary.

Pesticide use varies from year to year depending on a number of factors, including weather, pest problems, economics and types of crops planted.