ITER Frequently Asked Questions

Included on ITER? You will find answers to the most frequently asked questions including the different ways you can view the database.

What is ITER
Print a report?
Support ITER?
Search ITER?
Information on ITER?
Citing ITER?
included on ITER?
ITER update?
Make a suggestion?
View chemicals?
Sponsor  ITER?

What is ITER?

ITER (International Toxicity Estimates of Risk) is a free Internet database of human health risk values for over 680 chemicals of environmental concern from several organizations worldwide. ITER is the only Internet database that provides this data in a table format that allows side-by-side comparisons of risk values from different organizations. Below the table is a synopsis that includes an explanation for any differences among the organizations' values.

How do I search ITER?

ITER is currently available  

What's included on ITER?

ITER contains data from national and international organizations worldwide. ITER provides links to these organizations for more detailed information. ITER currently contains data from:  

Agency for Toxic Substances and Disease Registry (ATSDR)   ATSDR derives minimal risk levels (MRLs), which are found in the Agency's Toxicological Profiles.  

Health Canada   Health Canada develops Tolerable Intakes/Concentrations and Tumorigenic Doses/Concentrations for Priority Substances under the Canadian Environmental Protection Act (CEPA). These risk values for Health Canada are included on ITER. 

International Agency for Research on Cancer (IARC)  We are currently adding IARC's data to ITER. Look for announcements about this on ITER’s “What’s New” page.  

IARC evaluates the cancer weight of evidence for chemicals over a wide range of human exposures and classifies chemicals according to potential for carcinogenicity. The results of IARC analyses are published Monographs. IARC cancer classification groups and detailed descriptions of these groups can be found in the Preamble to each monograph and at The IARC evaluation considers the evidence of carcinogenicity in humans, the evidence of carcinogenicity in experimental animals, and other data relevant to the evaluation of carcinogenicity and its mechanisms.

NSF International

NSF International, an independent, not-for-profit organization, derives action levels [the total allowable concentration (TAC), single product allowable concentration (SPAC), and short-term exposure level (STEL)] for contaminants detected in laboratory testing of products in contact with drinking water and food. The basis for the action levels is the oral reference dose (RfD) for non-cancer risk assessment and the appropriate risk level for carcinogen risk assessment. U.S. EPA non-cancer and cancer risk assessment procedures are followed and a risk assessment document is prepared.  

National Institute of Public Health and the Environment (RIVM), The Netherlands   RIVM develops human-toxicological risk limits (i.e., maximum permissible risk levels, MPRs) for a variety of chemicals based on chemical assessments that are compiled in the framework of the Dutch government program on risks in relation to soil quality. The MPRs updated in 2001 have been added to ITER.  

Texas Commission on Environmental Quality (TCEQ)

TCEQ derives risk values called Effects Screening Levels (ESLs), inhalation Reference Values (ReVs), and inhalation Unit Risk Factors (URFs), which are published in Development Support Documents (DSDs). DSDs summarize how chemical-specific toxicity values were derived based on published guidelines (RG-442, TCEQ Guidelines to Develop Toxicity Factors).  

U.S. Environmental Protection Agency (EPA )

EPA derives risk values called reference concentrations (RfCs), reference doses (RfDs) and cancer assessments. All of these risk values from EPA’s Integrated Risk Information System (IRIS) are included on ITER.  

Independent parties whose risk values have undergone peer review

Risk values developed by other parties (e.g. industry, consulting groups, government, universities, etc.) that do not meet the criteria for having their own column on ITER (such as having data for at least 40 chemicals) are included on ITER under the ITER PR column or the IPRV column after they have undergone an independent peer review.  

ITER PR Column

The ITER PR column contains data from those organizations whose risk values have undergone peer review through TERA’s ITER Peer Review process ( This independent peer review is convened by TERA through its Peer Review Program, and if the expert panel concurs with an assessment, it can be made available to the public on the ITER database. Over two-dozen independent risk values have been included in the ITER PR column. Most of the independent values can only be found on ITER.

IPRV Column
The IPRV column contains data from those organizations that do not meet the criteria for having their own column (such as having data for at least 40 chemicals) and whose risk values have undergone peer review outside TERA’s ITER Peer Review process.  

Risk values are principally used as guidance or regulatory levels against which human exposures from contamination of air, food, soil, and water can be compared. The information on ITER is useful to risk assessors and risk managers needing human health risk values to make risk-based decisions. ITER allows the user to compare a number of key organizations' values and to determine the best value to use for the human exposure situation being evaluated. 

How do you view chemicals?

If you would like to view the data for a chemical, click on its chemical name. This will take you to the Level 1 table for that chemical, which contains red and gray circles for each organization and category (noncancer oral, cancer oral, noncancer inhalation, or cancer inhalation). The red circles indicate that ITER contains data, and the gray circles indicate that ITER does not contain data for that particular organization or category. (Note: In some cases the organization may have data available but it has not yet been prepared for inclusion in ITER. See the above section, entitled “What is ITER” to determine which organizations’ data is currently being added to ITER). Click on the red circles to go to the Level 2 table, which displays the key elements for each organization’s risk value along with a synopsis explaining any differences among risk values. At the bottom of the Level 2 table, you can click on the green circle(s) to go to Level 3 and obtain more information about a particular organization’s risk value (including a source and/or link for further information about that particular assessment).

How do I print a report?

If you want to generate and print a report, click on print

How is information gathered for ITER?

The values and text on ITER have been extracted from existing published documents and data systems of the original health organizations. TERA staff compiles information on the risk values into a consistent format, so that users can readily make comparisons across organizations. In some cases, the organization itself extracts and prepares data for ITER. TERA staff performs necessary conversions so that direct comparisons can be made when appropriate and write the synopsis text to help explain the similarities and differences between the values of the different organizations. The following explains the sources for ITER data. 

ATSDR information was extracted from the ATSDR Toxicological Profile for each chemical. Toxicological Profiles are published in both draft and final forms by ATSDR. For information call the ATSDR TOX-INFO LINE at (404) 639-6000 or see 

Health Canada information was extracted from Assessment Reports prepared by Environment Canada and Health Canada under the CEPA Priority Substances Program. These reports provide an assessment of risks to human health and are chemical specific. The most recent assessment reports, Environment Canada and Health Canada’s Canadian Environmental Protection Act, 1999: Priority Substances List Assessment Reports, are available online at Earlier reports were included in a 1994 publication, Evaluation of Risks to Health from Environmental Exposure in Canada. In: Environmental Carcinogenesis and Ecotoxicology Reviews, Part C of Journal of Environmental Science and Health. C12(2). This publication summarized the assessments of risks to human health of 44 Priority Substances that were written to fulfill the requirements of the CEPA. More detailed assessment reports and supporting documentation are available from the corresponding authors of each respective manuscript. New assessments will continue to be added as they are released. 

IARC information was extracted from the Summary and Evaluations in the IARC Monographs for each chemical. IARC Monographs are available at  

NSF International information is compiled from compound specific oral risk assessment documents prepared by NSF International. The complete documents are available from the NSF bookstore at

RIVM (The Netherlands) information was extracted from RIVM's 2001 document entitled, Re-evaluation of human-toxicological maximum permissible risk levels (RIVM report 711701025). This report can be found at  

TCEQ information was extracted from the Development Support Documents (DSDs). These documents can be found at 

U.S. EPA information was extracted from the Integrated Risk Information System (IRIS). IRIS is EPA's official source for agency consensus risk values. IRIS is available on-line at For additional information about IRIS, contact the U.S. EPA Risk Information Hotline at (301) 345-2870 or at

Independent parties’ information is derived from their risk assessment documentation, which has undergone independent peer review (see 

How often is ITER updated?

The ITER database is updated monthly.

How is ITER sponsored?

ITER was developed by TERA as a public service, to provide the international risk assessment community with easy access to the health risk values of many organizations and to provide a way to distribute independently derived peer-reviewed values. We are extremely grateful to our sponsors, without whom ITER would not have been possible. Additional support is needed to both maintain and expand ITER, and to continue providing ITER as a free service to the risk assessment community.

TERA has received support from a number of diverse organizations to help support the development and continual growth of the ITER database. Groups have supported ITER through funds or in-kind activities. These sponsors have included: 

- The Acrylonitrile Group, Inc. 
- The American Chemistry Council 
- Duke Energy 
- Concurrent Technologies Corporation (CTC) 
- Cytec Industries Inc. 
- Formaldehyde Epidemiology, Toxicology, and Environmental Group, Inc. (FETEG) 
- Health Canada 
- Metal Finishing Association of Southern California 
- National Institute of Public Health and the Environment (RIVM), The Netherlands 
- National Library of Medicine 
- Nickel Producers Environmental Research Association (NiPERA) 
- Noblis 
- NSF International 
- Syracuse Research Corporation 
- Texas Commission on Environmental Quality (TCEQ) 
- TERA developmental reserve funds 
- U.S. Borax 

How can I support ITER?

Thank you for your interest in helping support ITER, the only comprehensive Internet database of international risk values. We believe ITER is a great resource for international risk assessment information and hope you do too. As a nonprofit [501(c)(3)] organization, TERA funds ITER through grants and donations. TERA has been able to develop ITER as a free Internet database thanks to contributions of time, resources, and money, as well as through partnerships, from organizations such as those listed on our sponsors page. 

Financial Support 
In-Kind Support 
Feedback and Ideas for Improvements and Expansion 

You can help TERA expand this database through your financial or in-kind support, or through your ideas and feedback. We greatly appreciate any support you offer, and recognize that it will benefit the entire risk assessment community and beyond. 

TERA plans to expand the ITER database to include additional data from other countries and international organizations. Currently, ITER contains risk values and/or cancer classifications for 750+ chemicals from:

Agency for Toxic Substances & Disease Registry (ATSDR), 
Health Canada,  
International Agency for Research on Cancer (IARC) [in progress],  
NSF International,  
National Institute of Public Health and the Environment (RIVM), The Netherlands,   Texas Commission on Environmental Quality (TCEQ), 
U.S. Environmental Protection Agency (U.S. EPA)  
Independent parties whose risk values have undergone peer review.  

Your support will help us make risk assessment information readily available to people around the world, and will ultimately help protect public health. Please remember that your financial and in-kind contributions are also tax-deductible.  

Thank you for your support! 

how do I cite ITER?

General citation:   

TERA (Toxicology Excellence for Risk Assessment). 2020, International Toxicity Estimates for Risk (ITER) Database. Online. Cincinnati, OH. Available at: httsp://

Citing a specific chemical:   
TERA (Toxicology Excellence for Risk Assessment). 2020. International Toxicity Estimates for Risk (ITER) Database. Benzene (CAS 71-43-2). Online. Cincinnati, OH. Available at:

Can I make a suggestion?

TERA is interested in feedback on the content and format of ITER, as well as your suggestions for adding other organizations to ITER. Please send us your comments to TERA at