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.
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