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Author Ted Schettler
Science director
Dept of Medicine, Boston Medical Center
tschettler@igc.org
www.sehn.org
 
Comment
General comments on TRACI:

TRACI acknowledges large uncertainties in input parameters. It estimates a dose per unit release rate and assumes that that dose is equivalent throughout a large population. It makes no allowance for disproportionately exposed individuals who exceed that estimate because of where they are. (Landscape effects will be more or less important depending on the chemical of interest and manufacturing circumstances)

TRACI is meant to provide ranking and relative comparisons of chemicals rather than absolute risk. In doing so, TRACI acknowledges that estimating absolute risk is virtually impossible to do with validity because of multiple sources of uncertainty. Yet, the committee removed human cancer and non-cancer health effects from the TRACI analysis and attempted an absolute risk assessment. (No details are provided in the document to show any of the numerical values used or assumptions or simplifications). The authors justify that approach by saying that it provides a method for integrating the population wide health effects with the occupational health effects. However, the uncertainties in the population-wide analysis are so large that this integration becomes virtually meaningless.


I am including some comments below on specific sections of the draft report. Some are included as examples of the weaknesses and limitations in the committee’s general approach. These weaknesses strike at the core utility of the chosen method. As an exercise this project serves the purpose of showing that the method is not suitable to the task at hand.