PBBs

Polybrominated biphenyls (PBBs) are a class of organobromine compounds composed of two linked benzene rings with varying numbers of bromine atoms. Historically used as flame retardants, they were added to plastics, textiles, and electrical equipment to reduce flammability, especially during the mid-20th century as alternatives to polychlorinated biphenyls (PCBs). Because of their effectiveness and the plastics supply chains involved, PBBs were once encountered widely in consumer products and waste streams.

PBBs are persistent and lipophilic, tending to accumulate in soils, sediments, and living tissues. Environmental exposure occurs mainly through contaminated food, dust, and inhalation of airborne particulates near treated materials or waste sites. Their persistence means they can remain in the environment for long periods, gradually moving through ecosystems. Toxicological data indicate potential health effects related to endocrine, neurodevelopmental, and reproductive systems, with effects varying by congener and exposure level. However, risk assessments for humans at typical environmental exposures remain complex and ongoing.

Regulatory and industry status has shifted away from use in many regions. Many countries have restricted or phased out PBBs in consumer products and waste streams and have pursued safer flame retardants as substitutes. Disposal and remediation guidelines aim to limit release and exposure from aging or discarded materials.

A notable historical episode associated with PBBs occurred in the United States in the early 1970s, when PBB-contaminated cattle feed entered the food supply in Michigan. The incident prompted public health investigations and contributed to heightened scrutiny of flame retardants, product safety, and chemical regulation.