Now Playing: Risk Assessment Approaches and Application of IRIS Values - Panel Discussion
Moderators: Sandra Baird and Hugh Barton

Question 1: Joyce Tsuji and Michael Hansen
1a. “Science and Decisions” (NRC 2009) recommended that EPA adopt a unified dose-response assessment framework for cancer and noncancer end points. It has been suggested that an arsenic IRIS assessment might provide:
a. Risk estimates for noncancer end points (rather than or in addition to a concentration assumed to be health protective, such as an RfD)
b. Nonlinear cancer assessment
c. Multiple risk estimates for a single toxicity end point (e.g., alternative mode of action hypotheses, estimates from different studies, multiple dose-response models fitted to the same data)
d. Risk estimates for many toxicity end points
What recommendations do you have for EPA on use of these approaches? 1b. If the toxicological review of inorganic arsenic contains risk estimates derived from the dose-response approaches described in Question 1a, how would that impact the practice of risk assessment in the activities you are involved in?

Question 2: Barbara Beck and Kate Sande
2a. EPA has been asked by stakeholders to explicitly include consideration of populations that may have increased susceptibility to the adverse effects from arsenic (e.g., life stages, genetics, pre-existing disease, and environmental stressors such as co-exposures and nutritional deficiencies). What type of quantitative estimates of susceptibility would be useful in your risk assessment activities? If quantitative estimates cannot be derived, how do you recommend EPA provide information on susceptibility so that it can be used to inform your risk assessment activities?
2b. What types of documentation (and level of detail) are necessary to assist you and other users of an IRIS assessment if one of these approaches (which are not currently standard methods) were used?

Additional Questions for Workshop Speakers and Panelists from Committee