In September 2014, EPA and the U.S. Fish and Wildlife Service released an initial assessment of contamination at Tern Island, a remote island in the chain of Northwestern Hawaiian Islands (NWHI). The results show that there have been releases of hazardous substances such as polychlorinated biphenyls (PCBs) and lead from military wastes buried on the island between World War II and 1979, and further action is warranted.

Tern Island, located 564 miles northwest of Honolulu, comprises part of the Hawaiian Islands National Wildlife Refuge and Papahānaumokuākea Marine National Monument in the NWHI. It also lies within the Coral Reef Ecosystem Reserve managed by the National Oceanic and Atmospheric Administration and the State of Hawaii’s NWHI Marine Refuge.

The island was enlarged by the U.S. Navy in 1942 and used until 1946 as a naval airfield and aircraft refueling stop. It was subsequently occupied mainly by the U.S. Coast Guard for use as a Long Range Navigation (LORAN) radio station until 1979.  During this time the military discarded and buried materials such as batteries, capacitors, and transformers on-site. These materials have been shown to contain hazardous substances such as PCBs and lead, which are released into the environment.

Tern Island and its surrounding atoll, French Frigate Shoals, are designated as critical habitat for the Hawaiian monk seal, whose total population of 1,200 has been steadily declining in the NWHI. The atoll plays a vital role as the site of the largest breeding colony of the species, and faces loss of land habitat in the wake of climate change and projected sea level rise. The atoll is also nesting habitat for 95% of the population of threatened Hawaiian green sea turtles. Tern Island, the largest in the atoll, is the breeding site for 18 species of seabirds, the most in the NWHI.

The Center for Biological Diversity petitioned EPA in December 2012 to assess the sources and hazards posed by plastic pollution to the marine environment in the NWHI. Through its Superfund program and partnership with FWS, EPA conducted a “Preliminary Assessment” in response to the petition. Its assessment reviews the potential impacts on island wildlife from the military waste deposited on and around Tern Island.

The NWHI, including Tern Island, are located within the North Pacific Subtropical Convergence Zone, where a high concentration of marine debris from global sources accumulates, including plastics. The role of marine debris microplastics (defined as particles five millimeters and less) as a mechanism to concentrate and transport hazardous substances to marine species via the food chain also is discussed in the assessment. Initial studies conducted by EPA in areas outside of the NWHI indicate that microplastic marine debris can accumulate and transport contaminants in the marine environment into the food chain. Summaries of these and other plastic-related studies are referenced in the assessment.