NIOSHTIC-2 Publications Search

Illness associated with exposure to methyl bromide-fumigated produce - California, 2010.

O'Malley MA; Fong H; Mehler L; Farnsworth G; Edmiston S; Schneider F; Runge MJ; Pina R; Calvert GM
MMWR 2011 Jul; 60(27):923-926
Methyl bromide (MeBr) is a toxic gas used to fumigate agricultural fields and some produce. The U.S. Department of Agriculture (USDA) requires MeBr fumigation of grapes imported from Chile to prevent invasion by the Chilean false red mite, Brevipalpus chilensis. In 2010, two workers were exposed intermittently to MeBr over several months as part of their job inspecting produce at a cold-storage facility in Carson, California. Both workers had disabling neurologic symptoms (e.g., ataxia, memory difficulties, and dizziness) and elevated serum bromide concentrations. An environmental investigation revealed the potential for MeBr to accumulate in enclosed areas during the transportation and storage of fumigated grapes. Some MeBr air concentrations measured at a single point in time exceeded current 8-hour exposure limits, suggesting that exposure in confined areas could result in poisoning. Possible measures for facilities managers to consider to reduce postfumigation MeBr exposures include: 1) increased aeration time, 2) reduction of packaging that might absorb MeBr or limit aeration, and 3) changes in the stacking of pallets to improve air flow. Facilities should monitor air MeBr levels if they store MeBr-fumigated commodities in enclosed spaces entered by workers. Clinicians should consider occupational and environmental exposures in their differential diagnosis, and workers who might become exposed to fumigants should be informed of the health hazards related to these pesticides. The California Department of Pesticide Regulation (CDPR) was notified of MeBr exposure in one worker (patient A) after the treating physician contacted the California Poison Control System on March 19, 2010. Investigation by staff members of the Los Angeles County Department of Agriculture and CDPR confirmed that patient A had elevated serum bromide concentrations and that he had learned that a coworker (patient B) had similar symptoms. During April 13-21, 2010, CDPR conducted industrial hygiene testing, measuring MeBr concentrations at single points in time with samples obtained at several locations, using colorimetric indicator tubes sensitive to air concentrations ranging from 0.4 ppm to 80 ppm.* Sampling was conducted at three sites: the Port of Long Beach (PLB), where the imported grapes were fumigated with MeBr and then aerated; a cold-storage facility in Carson (facility A), where the two patients inspected produce, 6 miles from PLB; and a second cold-storage facility 215 miles from PLB in Tulare County (facility B), which was chosen to assess the effect on MeBr concentrations of transporting a shipment a long distance. (An erratum has been published for this article. To view the erratum, please visit the following site: <a href=""target="_blank"></a>
Health-hazards; Agricultural-products; Agricultural-workers; Agriculture; Agricultural-chemicals; Pesticides; Pesticides-and-agricultural-chemicals; Fumigants; Methyl-compounds; Bromides; Toxic-gases; Gases; Neurological-diseases; Storage-facilities; Poison-gases; Transportation; Food-handlers; Food-processing-workers; Exposure-assessment; Exposure-levels; Exposure-limits; Confined-spaces; Air-contamination; Air-flow; Air-monitoring; Air-quality-monitoring; Storage-containers; Poison-control; Air-sampling; Sampling; Disabled-workers; Employee-exposure; Medical-monitoring; Surveillance-programs
Geoffrey M. Calvert, MD, Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC, 4676 Columbia Parkway, Cincinnati, OH 45226
Publication Date
Document Type
Journal Article
Email Address
Fiscal Year
Issue of Publication
NIOSH Division
Priority Area
Agriculture, Forestry and Fishing
Source Name
Morbidity and Mortality Weekly Report
Page last reviewed: March 18, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division