Bromomethane, sources

This Statement was prepared to give you information about bromomethane and to emphasize the human health effects that may result from exposure to it. The Environmental Protection Agency (EPA) has identified 1,177 sites on its National Priorities List (NPL). Bromomethane has been found in at least 12 of these sites. However, we do not know how many of the 1,177 NPL sites have been evaluated for bromomethane. As EPA evaluates more sites, the number of sites at which bromomethane is found may change. This information is important for you to know because bromomethane may cause harmful health effects and because these sites are potential or actual sources of human exposure to bromomethane. 

No information is available on the effects of intermediate-duration oral exposure in humans, but two animal studies (Boorman et al. 1986 Danse et al. 1984) provide sufficient data to identify the main target tissue (the stomach epithelium) and to define the dose-response relationship for this effect. These studies are suitable for derivation of an intermediate oral MRL, but further studies would still be helpful to search more specifically for possible subclinical neurological effects. This is important since neurological effects appear to be the most sensitive effect by the inhalation route, and people may be exposed to low levels of bromomethane in drinking water drawn from contaminated groundwater sources. No information is available on intermediate- duration dermal exposure to bromomethane. However, humans are not likely to experience significant dermal exposures to bromomethane near waste sites, so research in this area does not appear to be essential. 

Use of bromine-containing additives (ethylene dibromide) in leaded gasoline results in the release of bromomethane in exhaust fumes (about 70-220 pg/m of exhaust) (Harsch and Rasmussen 1977), and this may have been significant source of bromomethane release in the past. Combustion of unleaded gasoline releases much less bromomethane (about 4-5 pg/m ), so current emissions from this source are presumably much lower than previously, and are likely to decrease further as leaded gasoline continues to be phased out. 

No information was located on any on-going studies on the fate and transport of bromomethane. However, two studies related to human exposure to bromomethane are being supported by the U.S. Department of Agriculture and conducted at the University of California, Davis. One project will analyze bromomethane residues on foods, and the second will quantitate exposure levels of field workers to bromomethane and develop appropriate procedures to minimize exposure from this source. Remedial investigations and feasibility studies at NPL sites that contain bromomethane will provide further information on environmental concentrations and human exposure levels near waste sites. 

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