Illnesses Associated with Chloropicrin use in California Agriculture, 1992 – 2003

Abstract

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.

Community Exposure Following a Drip-Application of Chloropicrin

“…Numerous community and occupational episodes associated with the off-site movement of chloropicrin fumigant mixtures have previously been documented. 6 The juxtaposition of new housing and agricultural land may prove problematic in other communities.…”

“…It has a specific gravity of 1.66 at 20°C, density of 1.65 g/cm 3 at 20°C. 6 It has a vapor density approximately 5.7 times that of air. 12 Although density affects the layering of nonmiscible fluids, vapor density does not affect calculation of pollutant vertical distribution according to the ideal gas law or Gaussian air pollution models.…”

“…7,8 Used in concentrations greater than 2%, chloropicrin is considered an active biocidal ingredient rather than a warning agent. 6 It can be mixed with other halogenated fumigants, including methyl bromide (18 products, 20% to 55% chloropicrin), dichloropropene (15 products, 15% to 60% chloropicrin), and methyl iodide (6 products, 0% to 75% chloropicrin). 9 There are no registered products mixing metam-sodium with chloropicrin or other halogenated fumigants.…”

“…This has been accompanied by multiple illness episodes in areas where treated fields are juxtaposed with housing. [3][4][5][6] …”

Evaluating Soil Solarization for Weed Control and Strawberry (Fragariaxananassa) Yield in Annual Plasticulture Production

“…From 1992 to 2007, there were a total of 1,015 cases with health effects definitely, probably, or possibly related to chloropicrin exposure reported to the California Pesticide Illness Surveillance Program (Beauvais, 2010;Oriel et al, 2009). Of these, 571 cases were associated with six incidents where chloropicrin was the sole active ingredient.…”