Overview#
Polybrominated biphenyls are a group of brominated flame retardants. They were added to plastics to slow ignition, but concern over their persistence and toxicity has pushed them out of use. They remain on the RoHS list as one of the original six restricted substances.
CAS
Varies by congener (group of related compounds)
Limit
0.1 percent per homogeneous material (RoHS)
Why restricted
Persistent, bioaccumulative brominated flame retardants
Typical use
Flame retardants in plastics (largely historical)
Where it's restricted#
Under RoHS PBBs are capped at 0.1 percent by weight per homogeneous material. They sit alongside the related diphenyl ethers, covered in PBDE.
Typical uses#
PBBs worked as flame retardants in plastic housings and components. Use was largely halted decades ago, so today the restriction mainly guards against contamination and legacy material.
Key point
PBB and PBDE are two distinct brominated families. RoHS restricts both, so a flame-retardant additive should be checked against each.