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Sacramento, CA, United States

Barry T.,Environmental Monitoring Branch | Oriel M.,Health and Safety Branch | Verder-Carlos M.,Health and Safety Branch | Mehler L.,Health and Safety Branch | And 3 more authors.
Journal of Agromedicine | Year: 2010

Objectives. To evaluate illnesses resulting from community exposure to chloropicrin on October 5, 2005, in the agricultural community of Salinas, California. Methods. A cross-sectional interview survey was conducted of 142 households downwind from the application site in neighborhoods that were sources of emergency calls. A total of 439 residents of the 142 households in affected neighborhoods and 1 emergency responder were interviewed. The authors assessed exposure to chloropicrin resulting from the application using a public domain air pollution dispersion model, the Industrial Source Complex 3 (ISC3). Results. A total of 440 subjects were represented in the interviews, including 324 (73.6%) who reported symptoms possibly or probably related to chloropicrin exposure. Ocular symptoms were present in 302 (93.2%) of the symptomatic cases. Nonocular (usually systemic or respiratory) symptoms occurred in 170 cases (52.5%), but occurred significantly more frequently in residents who lived within 0.46 miles of the application site. Air-modeling showed a plume of chloropicrin in the affected neighborhoods, with estimated 1-h TWA (time-weighted average) air concentrations between 0.15 and 0.025 ppm. Conclusions. Ocular, respiratory, and systemic symptoms on the evening of October 5, 2005, corresponded to a plume of chloropicrin, with estimated concentrations as high as 0.15 ppm, in the community of Salinas, California. Cases occurred between 0.36 and 2.89 miles from the application site. Use of irritant agricultural fumigants near residential neighborhoods can produce a risk of illness for distances more than 2 miles from the site of application. Air modeling is useful for evaluating the relationship between possible exposures and community symptoms. © Taylor & Francis Group, LLC.

Shaw B.D.,University of California at Davis | Wei J.B.,University of California at Davis | Tuli A.,Environmental Monitoring Branch | Campbell J.,UgMO Technologies | And 4 more authors.
Vadose Zone Journal | Year: 2014

Nitrate is often present in surface water, soil solution, and groundwater at undesirable or toxic levels. This study follows development of an in situ nitrate monitoring probe and examines its performance in the presence of potentially interfering ionic species and dissolved organic carbon (DOC). Ultraviolet (UV) absorption spectroscopy measurements of aqueous NO3 − were obtained under conditions where prevalent ionic species (i.e., Na+, K+, Ca2+, Mg2+, NH4 +, Zn2+, Cu2+ Mn2+, Fe2+, Fe3+, Al3+, Cl−H2PO4 −, HPO4 2−, SO4 2−, and HCO3 −) and DOC were present at maximum characteristic concentrations for a range of pH levels, allowing UV interference on NO3 − concentrations from individual ions to be investigated. While most solutions did not show interference, Fe2+ ions and DOC absorbed ultraviolet light strongly in regions of the spectrum where NO3 − also exhibited significant absorption. Natural water samples showed very low concentrations of Fe2+, which do not cause interference with nitrate measurements. A two-wavelength measurement scheme was adopted to correct for the potential interference of DOC in measurements of aqueous NO3 −. A multivariate calibration is presented to account for possible interference from both DOC and other ions in solution. The application of the UV spectroscopy probe is especially useful for deep vadose zone measurements of nitrate, as typically DOC concentrations will exponentially decrease with depth, and ion interference will be low. © Soil Science Society of America.

Starner K.,Environmental Monitoring Branch | Goh K.S.,Environmental Monitoring Branch
Bulletin of Environmental Contamination and Toxicology | Year: 2012

Seventy-five surface water samples were collected from three agricultural regions of California and analyzed for the neonicotinoid insecticide imidacloprid. Samples were collected during California's relatively dry-weather irrigation seasons in 2010 and 2011. Imidacloprid was detected in 67 samples (89%); concentrations exceeded the United States Environmental Protection Agency's chronic invertebrate Aquatic Life Benchmark of 1.05 μg/L in 14 samples (19%). Concentrations were also frequently greater than similar toxicity guidelines developed for use in Europe and Canada. The results indicate that imidacloprid commonly moves offsite and contaminates surface waters at concentrations that could harm aquatic organisms following use under irrigated agriculture conditions in California. © 2012 Springer Science+Business Media, LLC.

Starner K.,Environmental Monitoring Branch | Goh K.S.,Environmental Monitoring Branch
Bulletin of Environmental Contamination and Toxicology | Year: 2013

Due to frequent contamination of streams in the San Joaquin Valley, California, USA, with the insecticide chlorpyrifos, researchers are working to identify crop-specific management practices that will reduce the offsite movement of this compound into surface waters. To guide this effort, crops treated with chlorpyrifos in the vicinity of contaminated streams were identified; walnut, alfalfa, and almond were the primary crops identified. Use was higher on walnut and almond, but due to irrigation practices offsite movement in surface runoff may be more likely from alfalfa. Based on these findings, development of management practices to reduce off-site movement of chlorpyrifos in irrigation runoff from treated alfalfa fields is recommended. © 2013 Springer Science+Business Media New York.

Zhang X.,Environmental Monitoring Branch | Starner K.,Environmental Monitoring Branch | Spurlock F.,Environmental Monitoring Branch
Bulletin of Environmental Contamination and Toxicology | Year: 2012

Chlorpyrifos is a common surface water contaminant in California, USA. We evaluated five years of chlorpyrifos use and surface water monitoring data in California's principal agricultural regions. Imperial County and three central coastal regions accounted for only 10 % of chlorpyrifos statewide use, but displayed consistently high aquatic benchmark exceedances (13.2 %-57.1 %). In contrast, 90 % of use occurred in Central Valley regions where only 0.6 %-6.5 % of samples exceeded aquatic benchmarks. Differences among regions are attributable to crop type, use intensity, irrigation practices and monthly application patterns. Application method did not appear to be a factor. © Springer Science+Business Media, LLC 2012.

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