Project title: An Investigation of Perfluorinated Compounds (PFCs) in Puget Sound Shellfish
Completed in: 2009
Among the many concerns facing residents of Puget Sound are toxicants in our environment. Toxicants that end up in our marine environment pose an extra threat to human, animal, and environmental health. The Washington State Department of Ecology (Ecology) has prioritized research to understand the sources and strategies to reduce the threat these chemicals represent in the state. One of the classes of chemicals of concern is phthalates. Of particular concern is bis(2-ethylhexyl)phthalate, commonly abbreviated DEHP, which is a common compound in the creation of plastics and occurs in air, water, and soil around Puget Sound. One of the tasks incorporated in Ecology's approach to controlling toxic chemicals in Puget Sound is utilizing numerical models to assess movement through different media and predict levels in the environment. In line with this method, an eight-box fate-and-transport model was developed for the central Puget Sound region, focusing on the water column (shallow and deep depths), sediment, and biota. DEHP is a non-ionic organic chemical, which lends itself well to using established Mackay-type modeling techniques to estimate movement through the environment. The relative abundance of empirical data in various media (e.g., sediment, animal, and water) will allow comparison to the box model's prediction. Input data for the model were obtained from a variety of sources, although Ecology's Environmental Information Management (EIM) database was particularly useful as it provided sediment data collected over a 26-year time period. Calculations were also performed to understand the various exposure pathways of DEHP. Modeling of dermal exposure via water, as well as ingestion of shellfish and finfish was performed in order to quantify the total exposure residents of Puget Sound are experiencing when compared to the general US population. Successful validation of both types of computer models will yield a useful tool for public health agencies, researchers, and organizations involved in cleanup efforts to use to better understand the movement of DEHP -- and perhaps with additional modifications, other contaminants -- in the Puget Sound region.