Museum's Plastic Awareness weekend highlights capital's floating wildlife threat.
Scientists from the Museum and Royal Holloway, University of London, are warning of an unseen stream of plastic flowing along the river bed of the upper Thames Estuary, threatening aquatic wildlife.
The research team were originally using small nets to study Chinese mitten crabs and eels in the Thames but began to document the rubbish collected over a three-month period.
More than 8,000 pieces of plastic were pulled up from the river bed, only partly illustrating the extent of the problem since larger items such as plastic bags escaped the small nets.
More than a fifth of the submerged river of litter is made up of sanitary products, the rest from cigarette packets, food wrappers and cups, with most Londoners not even aware it's there.
The Thames tide breaks up the plastic rubbish into smaller and smaller fragments, which are then eaten by birds, fish and smaller animals, such as crabs.
Scientists are calling for a change in consumer behaviour as the scale of plastic pollution becomes clear.
This then introduces toxic chemicals into the food chains of river ecosystems and the North Sea, into which the Thames flows.
Museum researcher Dr Paul Clark, co-author of the study, said the toxic chemicals in the plastic could harm the health of wildlife.
The scientists are calling for a change to policy and consumer behaviour as the danger of litter hidden below the surface of the Thames becomes more apparent.
Marine biologist Dr Dave Morritt at Royal Holloway said, 'This underwater litter must be taken into account when estimating the amount of pollution entering our rivers and seas, not just those items that we can see at the surface and washed up on shore.'
The Museum held a Plastic Awareness Weekend on 4 and 5 January 2014, with scientists discussing the study in talks in the Attenborough Studio. EcoTales and Thames21 ran family activities, including the construction of a huge mosaic from recycled plastic.
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