Published online 9 July 1998 | Nature | doi:10.1038/news980709-1

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Do flame-retardants extinguish sea life?

Brominated flame retardants are used in products as diverse as cars and computers, textiles and television sets. Some of the chemicals are similar to the now banned PCBs (polychlorinated biphenyls) and DDT, which were also used as flame retardants and as pesticides. Does this chemical similarity mean we should be worried about the brominated products?

According to a report in the 2 July 1998 issue of Nature, it seems that perhaps we should. The chemicals have turned up in the body tissues of whales and dolphins, showing that they may be polluting the oceans.

Jacob de Boer of the Netherlands Institute for Fisheries Research in IJmuiden, the Netherlands, and his colleagues describe how the most commonly used brominated flame retardants - PBBs (polybrominated diphenyls) and PBDEs (polybrominated diphenyl ethers) - have similar chemical behaviour and are similarly toxic to PCBs and DDT. These chemicals were banned because they were suspected to be carcinogenic and to mimic the female hormone oestrogen.

"Despite the similarities in environmental behaviour and toxicity with well-known compounds as PCBs and DDT, no bans have been enacted, and the production of these flame retardants has continuously increased," say the researchers.

More than 150,000 tonnes of these chemicals are made annually around the world. Many materials that could catch fire easily are impregnated with brominated flame retardants for protection. The chemicals are incorporated into the matrix of various plastic materials, such as polystyrenes, and in this form are prone to leaching out. They can be directly absorbed by humans from plastic computer and TV casings, as well as being emitted from electronic circuit boards.

Although short-term exposure to the chemicals is probably harmless, long term exposure and build-up in the body could have more serious effects. Precisely the properties that make them so attractive in industry - their stability and heat resistance - are the properties that make them dangerous to wildlife, as once they reach the environment and the food chain, they will persist and are likely to accumulate in biological tissues.

But are they reaching the environment in noticeable quantities? De Boer and colleagues believe they are, as they have found both PBBs and PBDEs in the tissues of whales, dolphins and fish from the North Sea coast and the Atlantic Ocean.

Researchers took samples from whales stranded on the Dutch coast. They found the highest levels of the chemicals in a whitebeaked dolphin (Lagenorhynchus albirostris) from the North Sea. But there were also traces in sperm whales (Physeter macrocephalus), a minke whale (Balaenoptera acutorostrata), a harbour seal (Phoca vitulina), and in one fish sample, a mackerel (Scomber scombrus) from the southern North Sea.

The most worrying finding was a high level of PBDEs in sperm whale blubber. Sperm whales live and feed in deep waters, showing that the compounds have reached the food chain in deep ocean waters.

The researchers find that the chemicals are perhaps even more persistent than PCBs, and resist metabolic breakdown in tissues. Although there is no evidence that they are carcinogenic themselves, they may promote the carcinogenicity of other chemicals and are also listed as chemicals that can affect hormonal regulation.

The very fact that these chemicals are building up in the bodies of marine mammals, yet continue to be produced and widely used, suggests, the researchers claim, that an environmental problem similar to that caused by PCBs may be on its way.

From Nature 7 July 1898.