Risk Assessment

Ecological Soil Screening Level (Eco-SSL) Guidance and Documents

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:

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:

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. 

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/.

    Availability of Eco-SSL Values- April 4, 2005    
Contaminant Plant Soil Invertabrates Mammalian Avian
Aluminium Narrative Statement
Antimony No Yes Yes No
Arsenic Yes No Yes Yes
Barium No Yes Yes No
Beryllium No Yes Yes No
Cadmium Yes Yes Yes Yes
Chromium (III) No No Yes Yes
Chromium (IV) No No Yes No
Cobalt Yes No Yes Yes
Copper Yes Yes Pending Pending
DDT No No Pending Pending
Dieldrin No No Yes Yes
Iron Narrative Statement
Lead Yes Yes Yes Yes
Manganese Yes Yes Yes Yes
Nickel Yes No Pending Pending
PAHs No No Pending Pending
Pentachlorophenol Yes Yes Yes Yes
RDX No No Pending Pending
Selenium Yes No Pending Pending
Silver No No Pending Pending
TNT Yes No Pending Pending
Vanadium No No Yes Yes
Zinc Yes Yes Pending Pending

No- Minimum required data not available to derive Eco-SSL
Yes- Eco-SSL was derived
Pending- Eco-SSL is pending further review and evaluation of literature