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ASTER (ASsessment Tools for the Evaluation of Risk) was developed at the U.S. EPA, National Health and Environmental Effects Research Laboratory (NHEERL), Mid-Continent Ecology Division (MED), with funding from the U.S. EPA Office of Resource Conservation and Recovery (ORCR), and Office of Research and Development’s, National Center for Computational Toxicology. The objective was to develop an intranet application that could assist EPA in hazard ranking and the development of comprehensive risk assessments. ASTER is designed to provide high quality data for discrete chemicals, when available in the associated databases (i.e., ECOTOX and EcoChem), and QSAR-based estimates when data are lacking.

ASTER queries on a single chemical require users to enter a Chemical Abstract Services (CAS) Registry number, a chemical name, or the chemical’s structure as represented by a SMILES string.  Searches can also be conducted on multiple chemicals by uploading a comma delimited file of CAS Registry numbers or SMILES strings.

During single chemical processing, the software allows you to see details on how parameters were calculated or change critical information such as physical/chemical property data or the acute mode of toxic action. Reports are available in either an HTML or Microsoft Office Excel format.  The report provides chemical identification information, a summary of physical/chemical property and exposure information, ecotoxicity data either reported in the ECOTOX database or estimated using QSAR models, information on the chemical’s acute mode of toxic action, and all associated references.

Due to security restrictions, ASTER is not publicly available. EPA staff members or EPA contractors interested in using ASTER should contact ECOTOX Technical Support to obtain the access information. Employees of other government (tribal, local, state, national, international) agencies that require a search of the ASTER system must request a search through the ECOTOX Support staff, providing SMILES string(s) and/or CAS Registry number(s) for chemical(s) of interest.  Persons affiliated with government contracts/extramural agreements must submit their search requests through the funding governmental agency's Project Officer.

ASTER Quick Guide (PDF) (2 pp, 239K)
ASTER User Guide (PDF) (45 pp, 813K)

For more information on ASTER contact ECOTOX Support at T: (218) 529-5225 or E: ecotox.support@epa.gov.

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