Proceedings of the International Research Workshop on the Occurrence, Effects, and Fate of Microplastic Marine Debris, September 9-11, 2008, University of Washington Tacoma, Tacoma, WA, USA

S AND PRESENTATIONS Keynote Address How concerned should we be about microplastics? Dr. RC Thompson, University of Plymouth, Plymouth, UK Abstract: Microplastics are small fragments of plastic debris. This material has been reported on shorelines and in the water column on a global scale and there are concerns it may present hazards to wildlife and to human health. Microplastics are small fragments of plastic debris. This material has been reported on shorelines and in the water column on a global scale and there are concerns it may present hazards to wildlife and to human health. Methods to separate and quantify microplastics from environmental samples are time consuming and represent an incomplete estimate of contamination; however these semi-quantitative approaches have successfully identified microplastic as small as 20μm in diameter, have shown that the abundance of this debris has increased over recent decades and that microplastics are widely distributed in the environment. The sources of microplastic debris are most probably fragmentation of larger items of marine litter and the direct release of small pieces of plastic from various cleaning applications. Plastic products bring many societal benefits and as a consequence, annual global production has increased from 5 million tonnes in the 1950s to over 230 million tonnes today. However, because of their disposable nature substantial quantities of plastic items have been discarded to the environment and so the abundance of microplastic is likely to increase over the next few decades. Laboratory experiments have shown that microplastics are ingested by filter feeders, deposit feeders and detritivores and there is concern that ingestion of this material could present a physical hazard to wildlife, for example by compromising the ability to feed. In addition, there is evidence, that small fragments of plastic could facilitate the transfer of toxic substances to wildlife. Two routes have been suggested: (1) the release of chemicals incorporated during manufacture as plasticisers, flame retardants and antimicrobials, and (2) the release of persistent organic pollutants (POPs) that have arisen in the environment from other sources and have sorbed to plastic debris in seawater. Reaching robust, environmentally relevant conclusions about the abundance and the potential impacts of microplastic debris is not a trivial task and this workshop offers a major step toward identifying a suitable research agenda. There is also an important need for parallel research and policy focusing on solutions to established problems associated with the production, usage and disposal of plastics. Richard C. Thompson, PhD, is a Marine Ecologist specialising in the ecology of shallow water marine habitats. He studied Marine Biology at the University of Newcastle upon Tyne from 1988 to 1991 followed by a PhD on the ecology of intertidal biofilms at the University of Liverpool from 1992 to 1996. He subsequently worked as postdoctoral research fellow at the University of Southampton and since 2001 he has been a lecturer, and is now a Reader, in Marine Ecology at the University of Plymouth. He currently leads the BSc Marine Biology degree programme at Plymouth and lecture in marine ecology and experimental biology. His research has focused on a wide range of ‘natural’ ecological interactions and on anthropogenic disturbance. He supervises a research group of 2 post docs and 8 PhD students. Work by his group has examined: biodiversity and ecosystem function using rockpools as natural mesocosms, trade-offs between food availability and refuge quality, trophic linkages between intertidal and subtidal habitats, the ecology of coastal defenses and marine renewable energy developments. Much of his work over the last decade has focused on marine debris. In 2004 his group published a paper in Science describing the distribution and temporal trends in the abundance of microscopic fragments of plastic in the NE Atlantic. They have subsequently been working to establish the environmental consequences of this type of debris. He is currently acting as invited editor of a Theme Issue of 13 papers, for Philosophical Transactions of the Royal Society, focusing entirely on Plastics the Environment and Human Health. SESSION I: OCCURRENCE OF SMALL PLASTIC DEBRIS IN THE MARINE ENVIRONMENT Fate of Plastics Debris in the Marine Environment Dr. Anthony L. Andrady, Research Triangle Institute, Durham, NC, USA Abstract: Certain classes of plastics, those used in the fabrication of fishing gear and those used in packaging applications are present in quantity in the marine environment. Most of these are non-biodegradable formulations of nylons and polyolefins that are used in netting and ropes. Expanded polystyrene from packaging and floats as well as polyolefins from consumer packaging materials are also commonly present. Certain classes of plastics, those used in the fabrication of fishing gear and those used in packaging applications are present in quantity in the marine environment. Most of these are non-biodegradable formulations of nylons and polyolefins that are used in netting and ropes. Expanded polystyrene from packaging and floats as well as polyolefins from consumer packaging materials are also commonly present. The usual factors that facilitate the deterioration of these materials on exposure to land environments, mainly solar UV-B radiation and high temperatures have a limited impact floating plastics debris. This results in markedly retarded degradation of plastics in the oceans. Mineralization of these and their return to the carbon cycle must therefore be a very slow process. The plastic microparticles well known to be present in the oceans, likely originate from both the slow deterioration of the floating or submerged plastics, as well as the fragmentation of plastics degraded to embrittlement in the beach environment. Analysis of the collected particles cannot determine their origin but can only identify the chemical class of the plastic. Also, a significant fraction of the plastic fragments on beach and in water consists of virgin prils that mainly enter the environment during transport. These not being compounded will degrade at a relatively faster rate both on land and at sea. This discussion will summarize the chemical aspects degradation of the relevant classes of plastics, review the criteria for degradation in these systems and discuss the chemistries for enhancement of plastics degradation. Special emphasis will be on the origins and the fate of polymer microparticles. Tony Andrady, PhD, is a Senor Research Scientist at the Research Triangle Institute in North Carolina. He is a Material Scientist with a research interest in issues relating to plastics debris in the Marine Environment. Microplastics as Accumulators and Sources of Persistent Organic Pollutants in Marine Food Webs: How Significant? Dr. Alan J. Mearns, NOAA Office of Response & Restoration, Seattle, WA Abstract: It has been nearly 40 years since Carpenter and Smith (1972) first reported the occurrence of plastic spherules in the Atlantic, including confirming the ability of Long Island Sound spherules to accumulate PCBs (Carpenter et al, 1972). Only recently have scientists again started exploring the role of microplastics as accumulators and vectors of Persistent Organic Pollutants (POPs). Microplastics accumulate POPs to part per million concentrations. However, there remain differences of opinion about the significance of microplastics as vectors of POP accumulation in marine wildlife. When birds or juvenile fish ingest microplasics, which is worse to the health of organisms and populations: the undigestible plastic or the POP’s? Clearly, reducing microplastic inputs will reduce marine life injuries, regardless of the mode of injury. It remains unclear to what extent microplastics represent a source for food chain POP accumulation compared to other sources, such as marine organisms normal food. A risk assessment approach would help sort out the questions and their significance. It has been nearly 40 years since Carpenter and Smith (1972) first reported the occurrence of plastic spherules in the Atlantic, including confirming the ability of Long Island Sound spherules to accumulate PCBs (Carpenter et al, 1972). Only recently have scientists again started exploring the role of microplastics as accumulators and vectors of Persistent Organic Pollutants (POPs). Microplastics accumulate POPs to part per million concentrations. However, there remain differences of opinion about the significance of microplastics as vectors of POP accumulation in marine wildlife. When birds or juvenile fish ingest microplasics, which is worse to the health of organisms and populations: the undigestible plastic or the POP’s? Clearly, reducing microplastic inputs will reduce marine life injuries, regardless of the mode of injury. It remains unclear to what extent microplastics represent a source for food chain POP accumulation compared to other sources, such as marine organisms normal food. A risk assessment approach would help sort out the questions and their significance. Alan J. Mearns, PhD, is an Ecologist and Senior Staff Scientist with the NOAA Office of Response and Restoration in Seattle, Washington. He holds a PhD in Fisheries from the University of Washington and Master's and Bachelor's degrees in Biology and Zoology from California State University in Long Beach. During the 1970's Alan was Leader of the Biology Division at the Southern California Coastal Water Research Project (SCCWRP) and in the 1980's Ecologist for the MESA Puget Sound Project and Leader of the National Status and Trends Historical Trend Assessment Program which evaluated longterm contaminant trends along the entire US coastline. Since 1989 he has been a member of the NOAA ERD (HazMat) Team supporting NOAA's Scientific Support Coordinators (SSC's) during oil spills and