EPA's Superfund program issued ecological soil screening levels (Eco-SSLs) for thirteen contaminants that are frequently found in soil at Superfund sites. For background information on the development of Eco-SSLs and how they should be used in the Superfund ecological risk assessment process, see the following Memorandum:

• Release of Guidance for Developing Ecological Soil Screening Levels (Eco-SSLs) and Eco-SSLs for Nine Contaminants (PDF)(3 pp, 223 K, About PDF) 

Numerical soil concentrations were updated in March of 2005 for antimony, barium, beryllium, cadmium, cobalt, dieldrin, and lead. The updates did not substantially change the final Eco-SSL values:

• Update Sheet (PDF)(4 pp, 125 K)

In April of 2005, numerical soil concentrations were presented for arsenic, chromium III, chromium VI, pentachlorophenol, and vanadium. Narrative statements were developed for aluminum and iron, metals which are often found at high concentrations under background conditions. Eco-SSL guidance updated in February of 2005 describes how these values were developed and how they should be used in screening ecological risks. 

• Guidance for Developing Ecological Soil Screening Levels (Eco-SSLs) (PDF)(87 pp, 2.8 MB),

EPA plans to issue Eco-SSLs for up to 10 more contaminants next year, including values for copper, DDT, manganese, nickel, total PAHs, selenium, silver, and zinc.

The mammalian toxicity reference values developed for these contaminants can also be used in the baseline risk assessment for evaluating site risks. Following a peer-reviewed process, utilizing a large stakeholder group and reviewing every relevant published article to develop these Eco-SSLs, EPA expects that these new values will be widely accepted and used. The Guidance, the thirteen contaminant specific documents, and all the Attachments from the Guidance are available on-line at: http://www.epa.gov/ecotox/ecossl/.