ABSTRACT

Flame retardants are added to plastic materials, textiles, wood, hydraulic liquids etc. for reducing their inflammability. These substances reduce the heat and carbon monoxide formation in case of fire. They are added in high amounts, even up to 30% of product mass (e. g. plastic material). The production of brominated flame retardants has been steadily rising in the last 20 years, e. g. in the 1990s the world production of polybromodiphenyl ethers (PBDE) reached 40000 tons annually. Mainly polybrominated flame retardants are produced, e. g. polybromobiphenyls (PBB), PBDE, hexabromobenzene (HBB). Their toxicity is low or nil, the DL 50 values are over 1 g/kg. However, when administered in low doses over longer time periods they can cause changes leading to porphyria. The information on the toxicity of polybrominated flame retardants for humans is derived mainly from the accident in Michigan, where PBB contamination of fodder for farm animals occurred with consequent contamination of food. In consumers of contaminated food cutaneous changes and neurological and muscular symptoms were noted. Polybrominated flame retardants can be metabolized and undergo biodegradation mainly trough debromination. The data on the toxicity of debromination products point to di-and tribromobenzenes, some of which are highly hepatotoxic. In acute poisoning hepatocellular damage manifest itself as necrotic changes in experimental animals receiving 0.1-0.8 of DL 50 of di-or tribromobenzene. After repeated administration of lower doses the hepatocellular damage assumes the features of porphyrogenic injury. In the environment polybrominated flame retardants can be transformed by various factors (high temperature during fire accidents, incomplete incineration of waste) to polybrominated dibenzodioxins of dibenzofurans whose lethal doses can in extreme cases be 0.001 mg for 1 kg body weight.