EPA Draft Study on Portland Harbor Finds PCBs, Other Chemicals Pose Biggest Risks

摘要

Polychlorinated biphenyls are the most significant and widespread chemicals posing risks to humans and wildlife along the lower Willamette River, according to a draft remedial investigation report released by the Environmental Protection Agency Oct. 28.rnThe other major contaminants posing risks to humans and the environment include chlorinated dioxins and furans, the pesticide DDT, and polycyclic aromatic hydrocarbons, said the draft report on the Portland Harbor superfund site.rnThe ingestion of certain fish represents the primary exposure pathway for risk to both humans and wildlife, especially aquatic mammals, the draft report said. People who are in contact with the water and sediment have much lower risk, according to the study.rnChemical contaminants have higher concentrations in near-shore and off-channel areas. Sediments within the navigation channel have lower chemical contaminant concentrations. Moreover, the greatest chemical concentrations in sediment are located deep in the mud rather than closer to the surface. More chemicals probably were released into the river in the distant past than recently, according to the 7,000-page report.