of material more contaminated than that already on site. Proposed 
guidelines under PSDDA will require disposal decisions to be based on 
biological as well as chemical test results. 
Contaminants of Concern in Puget Sound Sediments 
Of the thousands of chemicals known or suspected to exist in the 
environment, only a small number have been measured routinely in detailed 
environmental studies. Chemicals that are considered a threat to the 
environmental health of Puget Sound (and other coastal areas across the 
country) share some common characteristics: 
t A demonstrated or suspected effect on human health or 
marine life 
t An identified past or present source of sufficient 
magnitude to be of concern 
t Potential persistence as a toxic contaminant 
t A potential for entering the food web. 
Several hundred chemicals have been tentatively identified in 
selected samples of Puget Sound sediments. Routine analyses have been 
conducted for only about 150 toxic chemicals and in only some areas of the 
Sound. Chemicals that have been frequently detected are limited to 
phenols, PAH, polychlorinated biphenyls (PCBs), other chlorinated 
hydrocarbons, some pesticides (e.g., DDT), and most metals. Lists of 
contaminants of concern has been developed by several agencies. A recent 
summary of contaminants of concern and their general properties has been 
published by the Puget Sound Estuary Program (Tetra Tech 1986a). 
Some of these chemicals are no longer actively produced (e.g., PCBs 
and DDT), but still enter Puget Sound from dumps, spills, and other waste 
sources. The sources of many toxic chemicals are difficult to distinguish 
or are widespread. For example, PAH come from the burning of wood, coal, 
and oil products; from leaking automobile oils and eroded highway 
pavement; and from a number of industrial processes including steel 
production and wood preserving. Other toxic chemicals have both human and 
natural sources. ' For example, arsenic comes from copper smelting 
operations and from ocean water, which contains naturally elevated levels 
of dissolved arsenic. 
Contaminant Accumulation and Burial 
Many factors influence contaminant dispersal and accumulation in 
Puget Sound. The manner in which a pollutant is dispersed from its point 
of introduction into the marine environment will be largely determined by 
its chemical properties, particularly its affinity for particles. The 
mobility, fate, and ecological impact of a chemical contaminant will be 
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