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

EPA's Superfund program issued ecological soil screening levels (Eco-SSLs) for seventeen inorganic and four organic 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:

• Release of Guidance for Developing Ecological Soil Screening Levels (Eco-SSLs) and Eco-SSLs for Nine Contaminants  Memorandum (Dec 2003)
• Update to the Guidance for Developing Ecological Soil Screening Levels (OSWER Directive 9285.7-55) (Feb 2005) (85pp, 3MB, PDF)

The interim Eco-SSL documents for the chemicals listed below provide an overview of the contaminant, separate discussion for each receptor group including a comprehensive list of literature evaluated under the effort, and a summary of data used in deriving Eco-SSL values.  The initial list of documents through Zinc are metal contaminants, and the documents that follow, beginning with DDT and Metabolites, are organic contaminants. The updates did not substantially change the final Eco-SSL values:

• Interim Ecological Soil Screening Level Documents for Metal and Organic Contaminants

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)

Eco-SSLs for copper and silver were released in 2006. In 2007, numerical soil EcoSSL concentrations were issued for DDT and metabolites, manganese, nickel, low and high molecular weight PAHs, selenium and zinc. The numerical soil copper, dieldrin and pentachlorophenol soil concentrations were updated in 2007, and the chromium III and chromium VI EcoSSLs were updated in 2008. Attachments 1-4, 4-1, 4-3 and 4-5 of the EcoSSL guidance were also updated in 2007.

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: Safer Chemical Research - Ecological Soil Screening Level.