Halogenated and brominated flame retardants

Pressures to introduce restrictive legislation in Europe have eased as the debate has moved from the political arena to focus on assessment and management of risk. The main health and environment issue centres on halogen-based FRs, for possible formation of dioxin-related products such as brominated dioxins/furans by polybrominated biphenyl ethers (PBBE) under combustion conditions. These are very effective flame retardants and are widely used in polystyrene, polyethylene and polypropylene. Only a few of 75 identified brominated dioxin ionomers and 135 brominated furan ionomers are toxic, and they are only present in low concentrations in combustion. Less-toxic furans tend to be formed more than dioxins, and brominated dioxine/furans are less toxic than their chlorinated counterparts. 

The most recent regulations include the International Programme of Chemical Safety (IPCS) environmental health criteria and the revised German Ordinance on dioxins. 

IPCS recommendations for decabromodipentyl ether and octabromodiphenyl-ether include hygiene measures, control of effluent and emissions, over 97% purity and controlled incineration. The IPCS expressed concern over the persistence of pentabromodiphenyl and polybrominated biphenyls and recommended that commercial use should cease until safety could be demonstrated. 

In 1994 the German Chemicals Banning (Dioxin) Ordinance was extended to include brominated dioxins/furans as well as chlorinated dioxins/furans. Certain tetra and penta-BDDs and BFDs were restricted (up to 10 ppb to July 1999 and 1 ppb thereafter) and higher limits (up to 60 ppb to July 1999 and 5 ppb thereafter) were imposed on total levels of specified hexa-, penta-, and tetra-BDDs and BDFs. 

Regulations restricting or banning the use of heavy metals impact more on additive manufacturers than on plastics compounders. The main effect is in forcing replacements for lead stabilizers and pigments, and cadmium-based 

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