Discarded plastics and priority pollutants: A multiple stressor in marine habitats

Background/Question/Methods

Hazards associated with plastic materials have become an issue of concern among environmentalists, scientists, industry workers and policy makers. Plastic products have been questioned for their safety due to adverse effects reported from various additives to plastics and some of the monomers that make up the material itself. In addition, discarded plastics have become a global environmental problem across several habitats. In the ocean, plastic pollution has been reported globally from coastal to pelagic habitats from the surface waters to the seafloor. Furthermore, several marine organisms across many trophic levels ingest plastic debris. The material itself may pose a threat to marine life, and in addition may be another medium for exposure to priority pollutants. Plastic waste interacts with other contaminants in the environment by sorbing priority pollutants such as persistent organic pollutants (POPs) and trace metals from surrounding waters. Plastic material in combination with priority pollutants threatens organisms as a multiple stressor. To better understand the risks of discarded plastics in marine habitats we asked two questions: 1) what is the fate of POPs to different types of plastics in marine habitats, and 2) what are consequences of ingestion of plastic material and marine plastic debris in fish. Using field experiments replicated over space and time, we measured sorption of PCBs and PAHs to five types of mass-produced plastics (HDPE, LDPE, PP, PET and PVC) in San Diego Bay. Next, we selected low-density polyethylene (LDPE) plastic for dietary exposure experiments. Adult Japanese medaka (Oryzias latipes) were exposed to one of three treatments (control diet, diet spiked with 10% virgin LDPE and diet spiked with 10% ocean-exposed LDPE) for 1- or 2-month periods and tested for several toxic endpoints including: changes in gene expression, transfer of pollutants from plastic to fish tissue, and histopathology.

Results/Conclusions

We found that different types of plastics sorb different concentrations of PAHs and PCBs. Significant differences among plastic types (p<0.001) suggest that some plastics may be less hazardous as marine debris. In medaka, we found changes in gene expression from both virgin and plastic exposed to the marine environment. Results gathered to date regarding effects of polyethylene plastic material itself and in combination with priority pollutants to medaka will be presented