POLLUTION LOCATOR|Ongoing Efforts to Improve Risk Scores

Scientists at the University of California at Berkeley and the Lawrence Berkeley National Laboratory are engaged in an ongoing collaboration to extend and improve Toxicity Equivalence Potentials with colleagues at the Center for Clean Products and Clean Technologies at the University of Tennessee, Knoxville, and at U.S. EPA's National Risk Management Research Laboratory. This work is currently focused on four areas:

EXTENDING TEP RISK SCORING TO MORE CHEMICALS
Work is ongoing to increase the number of chemicals that can be assigned TEPs, focusing initially on chemicals with substantial reported releases. Two low toxicity chemicals that comprise 80% of reported mass releases to water (nitrate and phosphoric acid) will be modeled. Because of uncertainties associated with treating metal compounds as if they were equivalent to the element, emphasis is also being placed on obtaining additional data for inorganic species of several metals such as lead, arsenic, cadmium, chromium, and nickel.

EVALUATING THE NEED FOR REGIONAL TEPS
The current TEPs in Scorecard are based on average data for the U.S. Researchers are evaluating whether TEPs differ significantly if they are derived for specific geographical regions in the U.S., different seasons of the year, and different population classifications (urban, suburban, rural).

DEVELOPING TEPS FOR OTHER ENVIRONMENTAL EFFECTS
Work is ongoing to develop TEPs that address ecological effects and important indirect environmental effects (acidification and tropospheric ozone formation potential).

CHARACTERIZING UNCERTAINTY
Work is ongoing to characterize the uncertainty and variability in TEPS calculated using CalTOX. Simulations are being run to assess the importance of chemical property uncertainty and landscape and exposure parameter variability on TEP values. This work should illuminate where the major sources of uncertainty in risk scoring are and focus attention on acquiring the information needed to reduce that uncertainty.