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| | Polybrominated biphenyls Basic information |
| | Polybrominated biphenyls Chemical Properties |
| Toxicity | Mixtures of brominated biphenyls with an average bromine content of six atoms
per molecule. PBBs have been used as flame retardants, but in
view of environmental and health problems such use is being
curtailed. Acute toxicity is low; rats given single oral doses of
17 g/kg exhibited no toxic effects. Most poisonings are due to
chronic exposure. Chronic doses of 67 mg/kg/day produced
anorexia, diarrhea, lachrymation and salivation, dehydration
and abortion in pregnant cows. |
| | Polybrominated biphenyls Usage And Synthesis |
| 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. |
| | Polybrominated biphenyls Preparation Products And Raw materials |
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