This report discusses environmental levels of methylchloroform (MC) based on a review of the literature and other information sources. The concentrations of MC in the U.S. atmosphere ranges from about 0.1 micrograms/cu m (20 ppt) in remote areas to over 500 micrograms/cu m (100 ppb) in some areas near where the substance is manufactured or used. The concentration drops off rapidly as one moves away from a source facility. Surface water contamination of MC range from somewhat less than 1 ppb to several hundred ppb in the vicinity of MC manufacturers. The highest measurement reported (3 ppm) was made in a roadside ditch near a producer site. MC has been detected but not quantified in U.S. drinking water except in one case when approximately 10 ppb was reported. Soil and sediment concentrations of MC appear to be no higher near manufacturers and users than in rural areas, though the data are very limited. The levels are on the order of fractions of a ppb. MC is a saturated chlorinated hydrocarbon which is relatively stable in the atmosphere. However, the molecule is susceptible to hydrolysis or dehydrohalogenation and reacts with water relatively rapidly and is thus degraded in soil and water. There are very few data on presence of MC in food raised and sold in the U.S. However, data from the United Kingdom suggest that MC is found on the order of parts per billion in some common foodstuffs. There is little evidence to judge whether MC accumulates in living organisms. Limited data on levels in marine organisms show levels on the order of a few parts per billion.

"EPA 560/6-77-030." EPA contract no. 68-01-1983. EPA project officer: Vincent J. DeCarlo. Section 6: Bibliography.