New persistent pollutant detected in deep sea fish

Triphenyltin may be joining the list of persistent organic pollutants, according to a new study. Unexpectedly high levels of TPT, the sister compound to tributyltin leached from boat anti-fouling paints, has been detected in deep sea fish.

Scientists at Spain’s Institute of Chemical and Environmental Research say the TPT levels they measured in deep-sea fish are surprising, because they are higher than those of tributyltin (TBT), a well-known related pollutant.

The study of marine life, published in a recent issue of Environmental Science and Technology along with a feature article, found that codfish living a thousand metres below the Mediterranean Sea contained levels of TPT higher than those found in coastal organisms.

The findings contrast sharply with the behaviour of TBT and other toxins such as PCBs and DDT, which accumulate mainly in fish living near harbours and boats, and decrease sharply with distance and depth. TPT’s increase with depth, on the other hand, shows that the chemical persists in the environment and can be transported long distances, the scientists told EST .

The study suggests that because TPT binds strongly to sediment particles, it can drift out to the deep sea undiluted. It may also be poorly metabolized by some species, say the scientists.

Organotin compounds will be phased out of antifouling paints by the end of the decade, following extensive studies of TBT bioaccumulation in marine organisms.

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