Persistent organic pollutants in plastic marine debris found on beaches in San Diego, California

Plastic debris were collected from eight beaches around San Diego County, California. Debris collected include: pre-production pellets and post-consumer plastics including fragments, polystyrene (PS) foam, and rubber. A total of n = 2453 pieces were collected ranging from <5 mm to 50 mm in size. The plastic pieces were separated by type, location, and appearance and analyzed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its breakdown products, and chlordanes. PAH concentrations ranged from 30 ng g−1 to 1900 ng g−1, PCBs from non-detect to 47 ng g−1, chlordanes from 1.8 ng g−1 to 60 ng g−1, and DDTs from non-detect to 76 ng g−1. Consistently higher PAH concentrations found in PS foam samples (300–1900 ng g−1) led us to examine unexposed PS foam packaging materials and PS virgin pellets. Unexposed PS foam contained higher concentrations of PAHs (240–1700 ng g−1) than PS virgin pellets (12–15 ng g−1), suggesting that PAHs may be produced during manufacturing. Temporal trends of debris were investigated at one site, Ocean Beach, where storm events and beach maintenance were found to be important variables influencing debris present at a given time.

► During beach surveys across San Diego County, most plastics (68%) were <5mm.
► Sampling following a storm event revealed an increase in the density of plastic.
► PAHs were greater than other POPs for all samples.
► Results suggest that PAHs are byproducts of manufacturing PS to PS foam.
► Weight of plastic debris does not reflect amount of POPs in plastic debris.