Skip to Content
United States National Library of Medicine National Institutes of Health

Fact Sheet
International Toxicity Estimates for Risk (ITER)

ITER is a toxicology data file on the National Library of Medicine's (NLM) Toxicology Data Network (TOXNET®). It contains data in support of human health risk assessments. It is compiled by Toxicology Excellence for Risk Assessment (TERA) and contains over 650 chemical records with key data from the Agency for Toxic Substances & Disease Registry (ATSDR), Health Canada, National Institute of Public Health & the Environment (RIVM) - The Netherlands, U.S. Environmental Protection Agency (EPA), the International Agency for Research on Cancer (IARC) (in progress), NSF International, and independent parties whose risk values have undergone peer review. ITER provides a comparison of international risk assessment information in a side-by-side format and explains differences in risk values derived by different organizations. ITER data, focusing on hazard identification and dose-response assessment, is extracted from each agency’s assessment and contains links to the source documentation. Among the key data provided in ITER are ATSDR’s minimal risk levels; Health Canada’s tolerable intakes/concentrations and tumorigenic doses/concentrations; EPA’s carcinogen classifications, unit risks, slope factors, oral reference doses, and inhalation reference concentrations; RIVM’s maximum permissible risk levels; NSF International's reference doses and carcinogen risk levels, IARC's cancer classifications, and noncancer and/or cancer risk values (that have undergone peer review) derived by independent parties.

Web Access/Searching

ITER is accessible, free of charge, via TOXNET at:

Users can search by chemical or other name, chemical name fragment, or Chemical Abstracts Service Registry Number(RN), and/or subject terms. Search results can easily be viewed, printed or downloaded. Search results are displayed in relevancy ranked order. Users may select to display exact term matches, complete records, or any combination of data from the following broad groupings:

Users can easily conduct their ITER search strategy against other databases: Hazardous Substances Data Bank®, Chemical Carcinogenesis Research Information System, GENE-TOX, IRIS, TOXLINE®, and ChemIDplus®.

Further Information

For detailed information about ITER or TOXNET, contact:

ITER Representative
Specialized Information Services
National Library of Medicine
Two Democracy Plaza, Suite 510
6707 Democracy Boulevard, MSC 5467
Bethesda, MD 20892-5467
FAX: (301) 480-3537
Telephone: (301) 496-1131

For comments on ITER content, contact:

ITER and RiskIE Manager
Toxicology Excellence for Risk Assessment
Telephone: (512) 863-5441

For general information on the Library's computerized information services, including ITER, contact:

Customer Service
National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894
Telephone: 1-888-FINDNLM (1-888-346-3656)

A complete list of NLM Fact Sheets is available at:
(alphabetical list)
(subject list):

Or write to:

Office of Communications and Public Liaison
National Library of Medicine
8600 Rockville Pike
Bethesda, Maryland 20894

Phone: (301) 496-6308
Fax: (301) 496-4450

Last reviewed: 09 May 2008
Last updated: 09 May 2008
First published: 14 January 2004
Metadata| Permanence level: Permanent: Stable Content