Human health risk assessment of endosulfan. I: Toxicology and hazard identification.

Endosulfan is persistent in the environment and toxic to wildlife. Legal mandates necessitate that a risk assessments be performed for endosulfan by the California Department of Pesticide Regulation (CDPR) and the United States Environmental Protection Agency (USEPA). This hazard identification (hazard ID) compared critical no-observed effect levels (NOEL) for acute, subchronic and chronic exposure intervals between the agencies. NOELs were discussed in light of their application to numerous exposure scenarios (occupational, general population and dietary). Only the acute oral NOELs differed between CDPR (0.7 mg/kg/day) and USEPA (1.5 mg/kg/day). Pregnant rabbits were considered by CDPR to be more responsive to low gavage doses of endosulfan than non-pregnant female or male rats in the acute study selected by USEPA. NOELs for other exposure routes and durations were similar between agencies. CDPR and USEPA concurred that a Food Quality Protection Act (FQPA, 1996) Safety Factor is not needed after evaluating all studies including a Developmental Neurotoxicity study. The SF was reduced to 1x. NOELs generated from this hazard ID will be used to calculate the Margins of Exposure for all scenarios and subsequently the risk characterization for endosulfan.

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. Of 62 subjects tested, 10-15% (depending upon the site of exposure) failed to detect 1200 ppb of chloropicrin (the highest concentrations tested). For exposures lasting 20 min, the minimum concentration detectable by 50% of the subjects was 75 ppb; the no-observed-effect-level (NOEL) for eye irritation was 50 ppb. Exposures for 1 hr, at 100 and 150 ppb, produced subjective eye irritation in most subjects. Using a standard tenfold uncertainty factor (Extoxnet 2006), an estimated NOEL for a 1-hr exposure to chloropicrin (calculated from the 100 ppb lowest-observed-effect-level) would be 10 ppb. The few monitoring studies conducted for agricultural use of chloropicrin demonstrate that the most sensitive effect to chloropicrin exposure is sensory irritation. The use of chloropicrin for field fumigation presents a difficult problem, both because of the extreme degree to which it is irritating, and because of the very low concentrations that cause such irritation. The cases summarized in this report, especially those resulting from applications that adhere to label and permit standards, suggest that additional mitigation measures are needed to minimize off-site human exposure associated with chloropicrin applications in California. Examination of the previously discussed Pesticide Illness Surveillance Program cases revealed that conducting the applications according to label directions and local permit conditions was not always adequate to prevent off-site exposure or resultant irritation or other symptoms. This suggests that current methods of fumigant containment and/or buffer zone requirements are insufficient under some circumstances.