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Chemical Fact Sheet

Chemical Abstract Number (CAS #) 74953
CASRN 74-95-3
SynonymsDibromomethane
Methylene bromide
Methane, dibromo
Analytical Methods EPA Method 502.2
EPA Method 524.2
EPA Method 8010
EPA Method 8021
EPA Method 8260
Molecular FormulaCH2Br2

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use IN ORGANIC SYNTHESIS SOLVENT FOR FATS, WAXES, & RESINS; HEAVY LIQUID IN SOLID SEPARATIONS; INGREDIENT OF FIRE EXTINGUISHING FLUIDS; GAGE FLUID
Apparent Color CLEAR, COLORLESS LIQUID
Boiling Point 96.95 DEG C
Melting Point -52.5 DEG C
Molecular Weight 173.83
Density 2.4970 @ 20 DEG C/4 DEG C
Environmental Impact Dibromomethane finds limited use in chemical synthesis, as a solvent, and as a gage fluid. It may be released to the environment during these uses as well as in its production and transport. Natural production by marine algae also adds to its environmental input. If released on soil, dibromomethane should volatilize from the soil surface and leach into the ground. If released in water, dibromomethane would be primarily lost by volatilization (half life 5.2 hr from a model river). Adsorption to sediment and bioconcentration in aquatic organisms should not be significant. No significant biotic or abiotic degradative processes have been reported in natural waters or soil. However, catalyzed photolysis may occur in surface layers of some natural waters or soil. In the atmosphere, dibromomethane will be lost by reaction with photochemically produced hydroxyl radicals. The estimated half life for this reaction is 213 days. Dibromomethane should also be readily scavenged by rain and snow. However, this dibromomethane will be returned to the atmosphere by volatilization. The general population will be exposed to low levels of dibromomethane in the atmosphere from both natural and anthropogenic sources. Limited occupational exposure via inhalation and dermal contact will also occur.
Environmental Fate Polyhalomethanes, including dibromomethane and tribromomethane, have been detected in surface water of the North and South Atlantic, in air samples collected in the lower marine and continental troposphere and in rain as well, collected in southern Germany. TERRESTRIAL FATE: Dibromomethane has a high vapor pressure and low adsorptivity to soil. Consequently, if released on soil, it will be expected to volatilize from the soil surface and leach into the ground. Catalyzed photolysis may take place on the soil surface. Its fate in soil and groundwater is unknown. AQUATIC FATE: If released in water, dibromomethane would be primarily lost by volatilization (half life 5.2 hr from a model river(1,SRC)). Catalyzed photolysis may occur in surface layers of some natural waters. ATMOSPHERIC FATE: In the atmosphere, dibromomethane will be lost by reaction with photochemically produced hydroxyl radicals. The estimated half life for this reaction is 213 days . Dibromomethane is very soluble in water (11,700 g/l at 15 deg C ) and therefore it should be readily scavenged by rain and snow.
Drinking Water Impact DRINKING WATER: In a survey of 14 treated drinking water supplies of varied sources in England, dibromomethane was detected in seven supplies . These supplies were derived from groundwater and surface water sources. Dibromomethane was detected in treated drinking water from the Niagara River in the range 0.2-0.8 ppb . GROUNDWATER: No detectible dibromomethane was found in samples from a study of groundwater contamination at 19 municipal and 6 industrial landfill sites in Wisconsin . Of the 377 and 282 representative samples of groundwater and surface water in New Jersey that were analyzed for dibromomethane, 12% and 28%, respectively, contained dibromomethane . Ninety precent of the samples of both types contained equal or less than 0.1 ppb of dibromomethane . The maximum dibromomethane concentration in groundwater was 44.9 and that in surface water was 358.6 ppb Dibromomethane was found at 9 of 17 stations in the Lower Niagara River; levels up to 5 parts per trillion were found . SURFACE WATER: Dibromomethane is a major volatile organic hydrocarbon in Narraganset Bay . However levels and distribution of the chemical were not reported. Surface seawater concentrations of dibromomethane at a site in the South Atlantic, and two sites in the North Atlantic (south of the Canary Islands and west of the Strait of Gibraltar) were 0.26, >1, and 0.3 ng/l . In Lake Ontario, dibromomethane was detected in 66% of the 82 stations that were sampled . Only 8 samples contained more than trace amounts of dibromomethane and the highest level was 7 parts per trillion. The detection limit was 0.7 parts per trillion. RAIN/SNOW: The concentration of dibromomethane in rain collected in Ulm, southern Germany was 1.4 ng/l . This rain was in a fast moving front coming from the North Atlantic. EFFL: In a comprehensive survey of wastewater from 4000 industrial and publicly owned treatment works (POTWs) sponsored by the Effluent Guidelines Division of the U.S. EPA, dibromomethane was identified in discharges of the following industrial categories (positive occurrences, median concn in ppb): nonferrous metals (8; 2.2), organics and plastics (2; 32.9), inorganic chemicals (2; 1.9), pesticides manufacture (2; 104.6), publicly owned treatment works (9; 0.3) . Maximum effluent concn >100 ppb were found in the nonferrous metals industry (286 ppb) and in pesticide manufacturing (151 ppb) . In a previous survey of 63 wastewaters from a wide range of chemical manufacturers across the U.S., 1 effluent contained dibromomethane . The level of dibromomethane in that sample was >100 ppb.

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