Ethylene dibromide (EDB; dibromoethane, glycol dibromide, bromofume) is a volatile, nonflammable, colorless liquid with a sweet, chloroform-like odor. It is currently used as a chemical intermediary, as a gauge fluid, and as a nonflammable solvent for resins, gums, and waxes. Historically, it was in widespread use as a lead scavenger in leaded gasoline, and as a pesticide and fumigant in soil and on grains, fruits, and vegetables, but its use has been restricted since 1984. It is a suspected human carcinogen and male reproductive toxin.
The odor of EDB is not detectable at a low-enough concentration to be considered a good warning to protect against excessive exposure. EDB readily penetrates skin, cloth, and protective clothing made of rubber and leather. Absorption and toxicity can occur by inhalation, ingestion, and dermal contact. At high temperatures, EDB releases hydrogen bromide, bromine, and carbon monoxide gas.
Mechanism of toxicity
Liquid EDB is a severe irritant capable of causing chemical burns and vesiculation of the skin. Inhalation of vapors produces respiratory irritation and delayed-onset pulmonary edema.
Once absorbed systemically, EDB is converted to 2-bromoacetaldehyde, which becomes irreversibly bound to macromolecules, including DNA, and inhibits enzymes, causing cellular disruption and reduced glutathione levels. Metabolism involves the cytochrome P-450 system oxidative pathway (CYP2E1) and a conjugated pathway (glutathione). The liver, kidneys, and testes are principal target organs of toxicity.
Inhalation. Fatalities have occurred among workers cleaning a tank containing residue of EDB.
Because EDB is a suspected carcinogen (Environmental Protection Agency [EPA] Category A2), no safe workplace exposure limit has been determined. Although the current Occupational Safety & Health Administration (OSHA) legal permissible exposure limit (PEL) is 20 parts per million (ppm) as an 8-hour time-weighted average with a ceiling of 30 ppm, the National Institute of Occupational Safety and Health (NIOSH) recommends a ceiling exposure of no more than 0.13 ppm. Exposure to vapors can produce lung irritation, and 100 ppm is the air level considered immediately dangerous to life or health (IDLH).
EPA has calculated a provisional reference concentration (RfC) of 0.0002 milligrams per cubic meter (mg/m3) for EDB based on reproductive effects in humans. An RfC is an estimate of a continuous inhalation exposure concentration to people (including sensitive subgroups) that is likely to be without risk for deleterious effects during a lifetime.
Ingestion of 4.5 mL of liquid EDB (160 mg/kg) resulted in death. EPA's drinking water maximum contaminant limit (MCL) is 0.00005 mg/L or 50 parts per trillion (ppt). EPA has not established a reference dose (RfD) for EDB.
Dermal application of as little as 16 mg/kg causes systemic intoxication.
Inhalation of EDB vapor causes irritation of the eyes and upper respiratory tract. Pulmonary edema usually occurs within 1–6 hours but may be delayed as long as 48 hours after exposure.
Skin exposure produces painful local inflammation, swelling, and blistering.
Oral ingestion causes prompt vomiting and diarrhea.
Systemic manifestations of intoxication include CNS depression, ...