Brominated naphthalenes are a group of compounds based on the naphthalene ring system, but where one or more hydrogen atoms have been replaced by bromine (75 brominated naphthalenes are possible). Crookes and Howe (1993) reviewed data on brominated naphthalenes and reported that the substances had no known commercial use and were not manufactured commercially, although it has been stated that 1-bromonaphthalene is used in refractive index testing of oils (Merck Index, 1989).

While brominated napthalenes do not appear to be manufactured commercially, they are being found as by-products in various chemical mixtures and a number of such occurrences have been highlighted by Crookes and Howe (1993).

The major reported release of brominated naphthalenes occurred in Michigan in 1973. Dairy herds were accidentally fed a flame retardant mixture, Firemaster BP-6 (or FF-1). The flame retardant was a polybrominated biphenyl mixture, but it was discovered that brominated naphthalenes were present at trace amounts in the commercial product. The incident resulted in the destruction of 788 tons of feed, 30,000 livestock, 1.6 million poultry, 17 tons of dry milk products and 5 million eggs. Although the brominated naphthalenes were present at only trace amounts, it is thought that they were primarily responsible for the acute toxic effects observed (Birnbaum et al, 1983, Goldstein et al, 1979; Hass et al, 1978).

The polybrominated flame retardants Firemaster FF-1 and BP-6 have been analysed for the presence of brominated naphthalenes. Firemaster FF-1 was found to contain 1 mg kg^-1 pentabromonaphthalene and 25 mg kg^-1 hexabromonaphthalene (O'Keefe, 1979). Firemaster BP-6 (an alternative formulation of Firemaster FF-1 without calcium silicate) contained 150 mg kg^-1 pentabromonaphthalene and 70 mg kg^-1 hexabromonaphthalene (Hass et al, 1978).

Hexabromonaphthalene has been reported to be present at a level of 150 mg kg^-1 in Firemaster FF-1 and BP-6. Tetrabromo- and pentabromonaphthalenes were also detected (Tondeur et al, 1984). 1-bromo-, dibromo- and bromochloronaphthalenes have been shown to be formed in the chlorination of water containing naphthalene and potassium bromide (Lin et al, 1984).

Monobromo-, dibromo- and bromochloronaphthalenes have been shown to be formed from naphthalene adsorbed on municipal incinerator fly ash and heated to 50-250⁰C in a stream of hydrogen chloride and helium. The source of bromine was thought to be bromide present in the fly ash (Eiceman et al, 1989). Traces of brominated naphthalenes have been shown to be present in the high temperature pyrolysis products of brominated flame retardants (Thoma and Hutzjinger, 1989).

Crookes and Howe (1993) reported that there was limited information on the environmental occurrence of polybrominated naphthalenes.

Crookes and Howe (1993) found no information on the volatility, atmospheric reactivity, adsorption to soil or sediments, bioaccumulation or anaerobic degradability of brominated naphthalenes. However, Walker and Wiltshire (1955) reported that two species of soil bacteria had been shown to be capable of utilising 1-bromonaphthalene as the sole carbon source.

An exhaustive literature review on the toxicity of polybrominated naphthalenes to marine organisms has not been carried out for the purposes of this profile. The information provided in this section is taken from existing review documents (Crookes and Howe 1993).

Crookes and Howe (1993) could not identify any aquatic toxicity data for polybrominated naphthalenes.

Crookes and Howe (1993) could not identify any bioaccumulation data for polybrominated naphthalenes.

Potential effects on interest features of European marine sites

• limited information on the occurrence, behaviour, toxicity and behaviour of these compounds in the marine environment should dictate that a precautionary approach is adopted in the control of these substances if found in European marine sites.

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