Dolphins contaminated with pollutants could be exposed to more toxic contamination if a dockyard is relocated.
The culprit is the pesticide, tributyl tin, an anti-fouling paint covering ships hulls, which is highly toxic. Research in Hong Kong has shown TBT causes deformity leading to infertility in sea snails.
The Environmental Protection Department has admitted contamination around shipyards is serious, due to paint stripping and discharging the waste water into the sea.
According to new research 8,840 nanograms of TBT per gram have been found in sediment and up to 280 ng per litre in water. The standard in Britain, Canada and Australia is 2 ng per litre. A nanogram is a billionth of a gram.
The levels are revealed in an environmental impact assessment for the relocation of Hong Kong United Dockyards floating dock from Yam O to Tsing Yi. At the dockyard, TBT levels of up to 4 million ng per litre were recorded in processed waste waters. TBT is now banned on vessels less than 25 metres long, but problems arise when vessels are stripped and repainted.
Manager of Hong Kong United Dockyards, George Windram, said the relocation would allow waste waters containing TBT to be treated. But the report says the relocation, which will involve dredging, would stir up and disperse TBT.