Polybrominated biphenyls

Chemical Properties

Hexabromobiphenyl is the predominant isomer. These materials are heavy, highly brominated compounds. PBBs are produced by direct bromination of biphenyl and it could be anticipated that very complex mixtures of compounds differing from each both in number of bromine atoms per molecule and by positional isomerism are formed. The possibility also exists (analogous to the PCBs) that halogenated dibenzofurans, for example, brominated dibenzofurans, may be trace contaminants in certain PBB formulations.

Uses

Polybrominated biphenyls (PBBs) are compounds that were formerly used as flame retardants in electrical products and in business machines and motor housings. There are 209 possible bromobiphenyl congeners, although only a small number have been synthesized and used. All of the commercial products contained a mixture of several individual PBBs. Commercial production ceased in 1977.

Health Hazard

PBBs are animal carcinogens, with the liver being the main organ affected.

Potential Exposure

The polybrominated biphenyls (PBBs) are inert substances and have been employed, primarily as fire retardants. For example, the PBBs were incorporated into thermoplastics at a concentration of about 15% to increase the heat stability of the plastic to which it is added. In 1973, one to two tons of PBBs, a highly toxic flame retardant, were accidentally mixed into an animal feed supplement and fed to cattle in Michigan. Contamination also resulted from traces of PBBs being discharged into the environment at the manufacturing site and at other facilities involved in handling PBBs. Approximately 250 dairy and 500 cattle farms were quarantined; tens of thousands of swine and cattle and more than one million chickens were destroyed; and lawsuits involving hundreds of millions of dollars were instituted. Before the nature of the contamination was recognized, many of the contaminated animals had been slaughtered, marketed, eaten; and eggs and milk of the contaminated animals were also consumed. Thus, large numbers of people have been exposed to PBBs; they are persistent in the environment and are concentrated in body fat. While commercial manufacture and distribution of PBBs have currently ceased, the full extent of the problem has not yet been assessed.

Shipping

UN3152 Polyhalogenated biphenyls, solid or Polyhalogenated terphenyls, solid, Hazard class: 9; Labels: 9-Miscellaneous hazardous material. UN3151 Polyhalogenated biphenyls, liquid or Polyhalogenated terphenyls, liquid, Hazard class: 9; Labels: 9-Miscellaneous hazardous material.

Incompatibilities

Polybrominated biphenyls (PBBs) are very unreactive. Materials in this category may be incompatible with strong oxidizing (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.; contact may cause fires or explosions) and reducing agents such as hydrides, nitrides, alkali metals, and sulfides. Also, PBBs may be incompatible with various amines, nitrides, azo/diazo compounds, alkali metals, and epoxides. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides.