Polybrominated biphenyls

Organic halogen compounds, built on brominated biphenyl structures, that are recognized toxins and suspected carcinogens, once used as flame retardants and in industrial applications. They are persistent in the environment and accumulate in fatty tissues, so they can reach the food chain and appear as contaminants in fish, meat, and dairy products. Because they resist breakdown, old contamination lingers in soils and sediments for decades. Monitoring programs track them in seafood and animal foods, and regulators set limits to keep dietary exposure as low as reasonably achievable. Their history is a warning about persistent chemicals entering food webs.