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.
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.
PBB and PBDE are two distinct brominated families. RoHS restricts both, so a flame-retardant additive should be checked against each.
Note: general educational information, not legal advice. Check the official source before relying on it.