December 3, 2013
‘Microplastic’ Waste Poisoning Marine Ecosystems
The dumping of human refuse has resulted in the world’s oceans being filled with tiny bits of plastic, and two new studies from a team of British researchers have found that high concentrations of these plastic bits severely impact the health of marine lugworms, an important part of marine food webs and the cycling of ocean sediments.
According to the studies, which were published on Monday in the journal Current Biology, lugworms are exposed to harmful chemicals, such as hydrocarbons, antimicrobials, and flame retardants, when they ingest tiny bits of marine plastic.
"These chemicals are persistent, meaning they could accumulate in the tissue of organisms and take a long time to break down," said study author Richard Thompson, a marine biology professor at Plymouth University in the UK. "Our laboratory studies provide the first clear evidence that microplastics could cause harm and show that this could result from both the physical presence of ingested plastic and chemical transfer. Our next steps will be to establish the full implications of these findings for organisms in natural habitats."
According to study author Stephanie Wright from the University of Exeter, marine lugworms also have a role outside any food chain.
“Lugworms also feed on and churn the organic content in sediments, much as earthworms in the soil do," Wright said. "If worms in contaminated environments were to reduce feeding levels by an amount comparable to that seen in that lab, it would mean significantly less turnover of sediment. In an area the size of the Wadden Sea, for instance, sediment turnover could drop by more than (34,000 gallons) each year."
Some plastics contain harmful chemical additives that can leach out into sediments and seawater. The tiny bits of plastic in the ocean can also concentrate water-borne chemicals, such as pesticides and detergents, on their surfaces.
When plastic enters the sea, it breaks down into ever-smaller pieces, which means many organisms can ingest this material in its various sizes. Although these plastics are associated with some of the most toxic chemicals regulated by the Environmental Protection Agency (EPA) and the European Union, they are still considered non-hazardous by policy makers.
"The hazard ranking of plastic within policy about debris needs to be reassessed, and funding from industry, not just government, (needs to be) directed towards research that adequately tests the safety of plastics in relation to humans and wildlife," said study author Mark Anthony Browne, a marine ecologist at Plymouth University.
"We believe our study has highlighted the need to reduce the amount of plastic waste and therefore microplastics which enter our seas," said study author Tamara Galloway, a professor of ecotoxicology at the University of Exeter. "Plastics are enormously beneficial materials. However, if marine plastic pollution continues to increase, impacts such as those demonstrated in our laboratory studies could occur in the natural environment.”
“It is therefore important that we prevent the accumulation of plastic and microplastic debris in marine habitats through better waste-handling practices and smarter choices in the materials we use,” Galloway added.