Q: Why is CDPR conducting air monitoring for pesticides?
A: In 2011, CDPR launched an air monitoring network in three agricultural communities across the state to expand its knowledge of the potential health risks of long-term exposure to pesticides. The intent of the network is to more accurately estimate health risks based on long-term exposure rather than extrapolate from short-term monitoring data to determine if additional protective measures are needed. 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. CDPR also conducts field studies to monitor exposure to workers and to measure how pesticides move and break down in air, soil and water.
Q: How are air monitoring sites selected?
A: Sites are selected based on pesticide use on surrounding farmland and demographics, including percentage of children, the elderly and farm workers. The network was designed based on knowledge learned during CDPR’s air monitoring 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.
Q: Where are the air monitoring stations for pesticides located?
A: From 2011 to 2016, there were a total of six stations monitoring for pesticides in California. Three were monitored by CDPR while three were monitored by the California Air Resources Board (ARB) at CDPR’s request. CDPR’s original network consisted of three stations in Shafter in Kern County, Salinas Municipal Airport in Monterey County and Ripon in San Joaquin County. At CDPR’s request, ARB also conducted monitoring at Ohlone Elementary School near Watsonville and Chualar Elementary in Monterey County, Oxnard in Ventura County and Santa Maria in Santa Barbara County because they are areas with high use of fumigant pesticides.
CDPR received funding to expand the air monitoring network to eight stations in 2017 and continuing through 2018. Three of the sites are monitored by DPR and five are monitored by ARB. The current sites selected for monitoring stations include: Chualar (Monterey County), Lindsay (Tulare County), San Joaquin (Fresno County), Shafter (Kern County), Santa Maria (Santa Barbara County), Cuyama (Santa Barbara County), Watsonville Area (Monterey County) and El Rio/Oxnard (Ventura County). For more information on the air monitoring program and site selections, see http://www.cdpr.ca.gov/docs/emon/airinit/air_monitoring_plan_2017.pdf.
Q: What pesticides are being monitored?
A: CDPR’s eight stations are currently monitoring for 36 pesticides and five pesticide breakdown products. The list includes methyl bromide, chloropicrin as well as other fumigants, and organophosphates, including chlorpyrifos. CDPR selected these pesticides based on the amount of use and their potential health risks. For more information on pesticides including in the current air monitoring program, see http://www.cdpr.ca.gov/docs/emon/airinit/air_monitoring_plan_2017.pdf.
Since 2017, methyl bromide is no longer used as a soil fumigant in agricultural production in the United States under the Montreal Protocol, an international treaty to protect the earth’s ozone layer. However, it can still be used under a quarantine/pre-shipment exemption that allows methyl bromide applications to kill pests on food commodities in storage prior to their export to other countries. The treatment is critical to prevent the spread of exotic pests and is required by the laws of most nations before accepting shipments.
In Monterey County, there is one company that fumigates produce, primarily strawberries prior to export. Pallets of strawberries are placed in fumigation chambers and fumigated with methyl bromide at a few pounds per 1,000 cubic feet, over the course of several hours. The chambers are then safely aerated prior to moving any fruit back into the cooler for export. Chamber fumigations have strict regulatory requirements just like field fumigations that include aeration requirements and buffer zones. Chamber fumigations use only a small percentage of methyl bromide compared to field fumigations which were performed at hundreds of pounds per acre.
Q: How is air monitoring conducted?
A: CDPR established levels for pesticides being monitored in the air to protect human health and the environment. The screening levels were set 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. CDPR or ARB scientists collect one 24-hour sample from each site weekly. Data collected from the Parlier pilot project demonstrated that monitoring a single location once a week provides adequate data to estimate chronic and sub-chronic exposures.
Q: What are the results of the air monitoring?
A: Since air monitoring began in 2011, most of the samples have had no detectable pesticide concentrations and a majority of pesticides detected were well below levels that indicate a health concern or need further evaluation. From 2011 through 2016, the pesticides detected the most often at CDPR’s stations were chlorpyrifos and Methyl isothiocyanate (MITC). Both were found at all three CDPR locations 28 percent of the time and at air concentrations that were low relative to the screening levels. Approximately 900 samples were collected and 6,000 analyses conducted each year through 2016.
In 2017, CDPR expanded its air monitoring program to include eight stations over a two-year period. DPR monitored a total of 31 pesticides and 5 pesticide breakdown products in four communities from January 1 through December 31, 2017. Pesticides monitored were selected based primarily on potential risk to human health. For 2017, no monitored pesticide exceeded any screening level or regulatory targets at any of the sampling locations.
Of the 7,396 analyses conducted, 92.9% had no detectable concentrations, 7.1% had a detectable (trace or quantifiable) concentration, and 1.6% had quantifiable concentrations. Nine of the 36 pesticides and breakdown products monitored were not detected. Seventeen pesticides and breakdown products were only detected at trace levels. Ten compounds were detected at quantifiable levels, including 1,3-dichloropropene, chloropicrin, chlorothalonil, chlorpyrifos and its oxygen analog, chlorthal-dimethyl, DDVP, EPTC, malathion, and methyl isothiocyanate (MITC).
For more information on CDPR air monitoring results see https://www.cdpr.ca.gov/docs/emon/airinit/air_monitoring_results/full_report.pdf
Q: How are the data collected being used?
A: CDPR 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. This information is used by CDPR to decide if further regulatory measures are necessary. It is not unusual to see slight variances in annual data and these may be caused by a number of factors. Variances in annual data over a few years do not necessarily indicate a health hazard.