A research team confirmed the occurrence of biomagnification of toxic substance TPT compounds along the marine food chain resulted in very high concentrations of TPT in two top predators, the Chinese white dolphin and the finless porpoises. This is the first study in the world to confirm the trophic magnification of TPT in food webs of cetacean species.
Globally, organotin compounds such as tribuyltin (TBT) and triphenyltin (TPT) have been widely used as antifouling agents on ship hulls and submerged mariculture facilities over the past decades. Hence, they are often detected in seawater, sediment and biota samples collected from coastal marine environments of urbanised coastal cities worldwide. At very low concentrations, these compounds can cause endocrine disruption or even death in marine organisms. The International Maritime Organisation (IMO) of the United Nations has implemented a global ban on the use of organotin compounds on the hull of sea-going vessels since 2008.
Together with their collaborators, Professor Leung’s research team discovered that despite a decline of TBT concentration in our marine environment in recent years, the levels of TPT contamination remained serious with an increasing trend. In addition to TPT contamination in seafood, the team’s recent research has also confirmed the occurrence of biomagnification of TPT compounds along the marine food chain, resulting in very high concentrations of TPT in two top predators, the Chinese white dolphin and the finless porpoises.
This is the first study in the world to confirm the trophic magnification of TPT in food webs of cetacean species, and the findings were recently published in Environment International.
Background TBT and TPT are highly toxic biocides which can cause growth inhibition to marine algae and mortality to many marine invertebrates and fishes at 1-50 ?g/L*. At very low concentrations (1-10 ng/L**), these compounds can cause endocrine disruption in marine organisms such as growth retardation and shell thickening in oysters, and abnormal development of male sex organs on females of gastropods. TBT and TPT accumulate along the food chain in larger organisms such as fish, and may have an adverse effect on health when consumed by humans.
Professor Kenneth Leung and his research team have been monitoring organotin pollution in the marine environment of Hong Kong since 2004. They discovered that TPT contamination remained serious with an increasing trend. TPT had been found in our seafood and in some case, their concentrations (e.g. those in tonguefishes) exceeded the food safety limit for human consumption. In 2017, the Government of the Hong Kong Special Administrative Region finally established a new legislation (Cap. 413, section 3) to support the IMO’s global ban of using organotin compounds on vessels, and enhance the control of their release.
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