Go to the EPA IRIS data base at http://www.epa.gov/iris/index.html Click on List of IRIS Substances. Select Heptachlor (not the QuickView). Answer the following questions in your own words:
a. What is meant by oral reference dose?
b. What types of studies did the EPA use to estimate the oral reference dose? (human, animal, or both?)
c. What was the adverse effect upon which the Agency based its estimate?
d. What are the major uncertainties in the estimate?