Pesticide and Nitrate Trends in Domestic Wells where Pesticide Use Is Regulated in Fresno and Tulare Counties, California.

The California Department of Pesticide Regulation initiated regulations on pesticide use in 1989 to mitigate groundwater contamination by atrazine [6-chloro--ethyl-'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] and subsequently for simazine (6-chloro-,'-diethyl-1,3,5-triazine-2,4-diamine), diuron ['-(3,4-dichlorophenyl)-,-dimethylurea], bromacil [5-bromo-6-methyl-3-(1-methylpropyl)-2,4(1,3)-pyrimidinedione], and norflurazon [4-chloro-5-(methylamino)-2-[3-(trifluoromethyl)phenyl]-3(2)-pyridazinone]. Annual water samples from 2000 to 2012 were obtained from domestic wells in Fresno and Tulare counties in regulated areas designated either as leaching groundwater protection areas (GWPAs), where residues move downward in percolating water, or runoff GWPAs, where residues move offsite in rain or irrigation runoff water to sensitive sites such drainage wells. Concentrations decreased below the reporting limit, so maximum likelihood estimation methodology for left-censored data was used.

Pesticides exposure assessment of kettleman city using the industrial source complex short-term model version 3.

Kettleman City, California, reported a higher than expected number of birth defect cases between 2007 and 2010, raising the concern of community and government agencies. A pesticide exposure evaluation was conducted as part of a complete assessment of community chemical exposure. Nineteen pesticides that potentially cause birth defects were investigated.

Community exposure following a drip-application of chloropicrin.

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.

Illnesses associated with chloropicrin use in California agriculture, 1992-2003.

With limitations imposed on the use of methyl bromide by international treaty, use of metam-sodium, chloropicrin, and other fumigants have increased; this increase has been accompanied by multiple community illness episodes. In this review we address the California experience of direct or indirect exposures to chloropicrin, after use of this fumigant as an active ingredient in agricultural pest control, from the years 1992-2003. The best available toxicology data demonstrate that, for brief exposures (5-30 sec), eye irritation (or at least "chemesthesis"--detection of exposure by the eye) occurred in 50% of volunteer subjects exposed to 700 ppb of chloropicrin.

Illnesses related to shank application of metam-sodium, Arvin, California, July 2002.

Objectives: To evaluate the health effects of methyl isothiocyanate (MITC) and other byproducts resulting from the soil-incorporated (shank) application of 25,000 pounds of metam-sodium on July 8, 2002, near the community of Arvin, California.

Methods: Residents in a four-block area were interviewed regarding eye and upper respiratory irritation, non-specific systemic symptoms, and lower respiratory complaints. The distribution of cases was compared to results of Industrial Source Complex (ISC3) air dispersion modeling for the metam-sodium byproduct, methyl isothiocyanate (MITC).

Modeling methyl isothiocyanate soil flux and emission ratio from a field following a chemigation of metam-sodium.

Metam-sodium had become the most heavily used soil fumigant in recent years as the deadline approached for methyl bromide to phase out in January 2005. After application, metam-sodium decomposes rapidly to methyl isothiocyanate (MITC), a highly toxic compound capable of killing a wide spectrum of soil-borne pests. Inhalation risk of MITC ranked high among airborne agricultural pesticides in California.

Modeling of methyl isothiocyanate air concentrations associated with community illnesses following a metam-sodium sprinkler application.

Background: A series of illnesses occurred in Earlimart, CA on November 13, 1999 following a metam-sodium sprinkler application to a potato field on the southern edge of the town.

Methods: Case information was obtained from direct interviews, from illness complaints filed with state or county agencies, or from illness reports filed by community physicians for 173 subjects. Air concentrations of the by-product methyl isothiocyanate (MITC) during the episode were estimated based upon the Industrial Source Complex Short-Term (ISC3) air dispersion model, estimates from prior metam-sodium monitoring studies, and data from weather stations in two adjoining communities.