An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Science Advisor Programs

Exploration of Aging and Toxic Response Issues: Final Report

Contract No. 68-C-99-238
Task Order 15
Prepared for: Risk Assessment Forum, EPA
Prepared By: Versar, Inc., 6850 Versar Center, Springfield, VA 22151
Clearly, most physiological functions undergo deterioration with increasing adult age and this deterioration undoubtedly increases vulnerability to harmful environmental agents. However, two important caveats need to be emphasized:
  1. The extent of this deterioration varies greatly between and within individuals
  2. Most investigators have attempted to quantify the extent of deterioration and variation using cross-sectional study designs

Thus, although strong qualitative evidence regarding age-associated physiological deterioration is available, data on the extent of deterioration are soft. 

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.