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The Science Behind Human Health:  EPA’s Integrated Risk and Information System

The IRIS program strengthens the scientific foundation that protects health and the environment.

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It’s a fairly safe bet that at some point, we’ve all taken a drink of tap water from a kitchen faucet, inhaled deeply while enjoying an afternoon outside, or tracked soil into our homes. Americans perform these and dozens of other mundane daily activities without giving a second thought to potential harmful consequences, thanks in large part to the U.S. EPA’s Integrated Risk Information System (IRIS).

EPA plays a critical role in providing high-quality health information on chemicals of concern. The Agency’s IRIS assessment program is a key part of this effort and includes human health assessments of more than 540 chemical substances.  These assessments provide the sound scientific basis for EPA decisions and are widely used by risk assessors, health professionals, and state, local, and international governments.

“EPA is committed to upholding the highest standard of scientific integrity in all of its activities,” said Paul Anastas, assistant administrator of EPA’s Office of Research and Development.  “This means constantly seeking to improve, strengthen, and enhance our scientific work to reflect the best available information.” Continuous improvement of the IRIS program is an important part of this ongoing effort.

In early July, EPA announced changes to the program that will help ensure that the Agency continues to use the best and most transparent science to pursue our mission of protecting human health and the environment. These latest changes build upon significant improvements initiated by Administrator Lisa Jackson in 2009. 

Since 2009, EPA has completed 16 assessments, more than the number of assessments that were completed in the previous 4 years. The average timeframe for completing assessments has been reduced from three years or more to within two years and the backlog of assessments in the pipeline is smaller.  These improvements have been accompanied by strong and continued emphasis on independent, transparent peer review of the IRIS program.

In April of this year, EPA received a report from the National Academy of Sciences on their review of EPA’s draft IRIS assessment of formaldehyde.   In the report, the NAS suggested ways to improve the IRIS process in two primary areas: accessibility and transparency.

Because EPA is constantly seeking feedback from credible, independent scientific sources, those suggestions were welcomed and are in the process of being fully incorporated into the IRIS program.  They include: 

  • Shorter, clearer, more concise and more transparent IRIS assessment documents.
  • Reduced volume of text and increased clarity and transparency of data, methods and decision criteria.
  • Consolidation of text into concise narrative descriptions.
  • Online public posting of all studies used in the assessment development.

In order to make the scientific rationale of IRIS assessments as transparent as possible, EPA will evaluate the strengths and weaknesses of critical studies in a more uniform way.  And, the Agency will clearly indicate which criteria were most influential in weighing scientific evidence in support of chosen toxicity values.

EPA will also establish a dedicated advisory committee that will exclusively serve to help assure the scientific rigor and transparency of IRIS assessments as the NAS recommendations are implemented.  And, EPA will add a peer consultation step to the early stages of major IRIS assessments to assure that the scientific community can provide input as critical design decisions for individual assessments are made.

These changes will be implemented over the coming months in a tiered approach—with the most extensive changes applied to those assessments in the earliest stages of development.

“All the improvements to IRIS are part of the natural evolution that accompanies all rigorous scientific work,” said Anastas. “We will continue to consider information and perspectives from independent scientific sources and pursue improvements on an ongoing basis.”


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