Plastic resin pellets as a transport medium for toxic chemicals in the marine environment

Plastic resin pellets (small granules 0.1-0.5 centimeters in diameter) are widely distributed in the ocean all over the world. They are an industrial raw material for the plastic industry and are unintentionally released to t he environment both during manufacturing and transport. They are sometimes ingested by seabirds and other marine organisms, and their adverse effects on organisms are a concern. In the present study, PCBs, DDE, and nonylpheno ls (NP) were detected in polypropylene (PP) resin pellets collected from fo ur Japanese coasts. Concentrations of PCBs (4-117 ng/g), DDE (0.16-3.1 ng/g ), and NP (0.13-16 mug/g) varied among the sampling sites. These concentrat ions were comparable to those for suspended particles and bottom sediments collected from the same area as the pellets. Field adsorption experiments u sing PP virgin pellets demonstrated significant and steady increase in PCBs and DDE concentrations throughout the six-day experiment, indicating that the source of PCBs and DDE is ambient seawater and that adsorption to pelle t surfaces is the mechanism of enrichment. The major source of NP in the ma rine PP resin pellets was thought to be plastic additives and/or their degr adation products. Comparison of PCBs and DDE concentrations in marine PP re sin pellets with those in seawater suggests their high degree of accumulati on (apparent adsorption coefficient: 10(5)-10(6)). The high accumulation po tential suggests that plastic resin pellets serve as both a transport mediu m and a potential source of toxic chemicals in the marine environment.