Title: Polybrominated Biphenyls
Additional Names: PBBs; brominated biphenyls; polybromobiphenyls
Literature References: Mixtures of isomers and congeners with structures similar to polychlorinated biphenyls, q.v., where each X = H or Br. Once widely used commercially. Prepn: H. Hahn et al., DE 1161547 (1964 to Chem. Fabrik Kalb); G. A. Burk, US 3733366 (1973 to Dow); L. C. Mitchell, D. R. Breckenridge, US 3763248 and US 3833674 (1973, 1974 both to Ethyl Corp.). Persistence in soils: L. W. Jacobs et al., J. Agric. Food Chem. 24, 1198 (1976). Photodegradation: L. O. Ruzo et al., ibid. 1062. Reviews of environmental hazards: K. Kay, Environ. Res. 13, 74-93 (1977); F. J. DiCarlo et al., Environ. Health Perspect. 23, 351-365 (1978); of toxicology and mechanism of action: S. Safe, Crit. Rev. Toxicol. 13, 319-395 (1984); of carcinogenicity: E. M. Silberhorn et al., ibid. 20, 439-496 (1990); of toxicology and human exposure: Toxicological Profile for Polybrominated Biphenyls and Polybrominated Diphenyl Ethers (PB2004-107334, 2004) 624 pp.
Derivative Type: Firemaster BP-6
Properties: Major component is 2,2¢,4,4¢,5,5¢-hexabromobiphenyl. Softens at 72°, dec >300°. Low vapor pressure; degraded by uv light. Very sol in benzene, toluene. Insol in water.
CAUTION: The 1973 "Michigan Incident" in which BP-6 was accidentally added to animal feed, and resulted in the contamination of the food chain and wide-spread destruction of contaminated farm animals, led to the removal of BP-6 from the market: L. J. Carter, Science 192, 240 (1976). Reported symptoms of overexposure include impaired immune system; hypothyroidism; neurological effects, headache, joint stiffness, memory loss; chloracne-like lesions (Safe). See also Patty's Industrial Hygiene and Toxicology vol. 2D, G. D. Clayton, F. E. Clayton, Eds. (John Wiley & Sons, New York, 4th ed., 1994) p 2433-2504. These substances are reasonably anticipated to be human carcinogens: Report on Carcinogens, Eleventh Edition (PB2005-104914, 2004) p III-217.
Use: Formerly as flame retardant. |