New risk-based hazardous waste regulations draw fire in California Environmental groups and industry in California have attacked a proposed state hazardous waste classification system that is based on an advanced risk assessment model. The revised classification is the first major regulatory application of CalTOX, a multimedia, mass-balancing model that incorporates uncertainty analysis. Critics praise the science behind CalTOX but disagree with the results and with how the model is being used. The model assesses multiple media, exposure pathways, and chemicals in setting threshold values for the waste classifications. Environmentalists claim that under the new system, wastes previously considered hazardous will be left untended or stockpiled at industrial sites. Industry is concerned that the new system, intended to relieve regulatory burdens, will actually increase them. The revised classifications were intended to simplify California's complex waste regulations. In addition to federal requirements, California has its own hazardous waste laws that regulate roughly 50% more substances than do federal regulations. The proposal creates three broad waste categories: nonhazardous waste, managed industrial waste, and hazardous waste. The state's Department of Toxic Substance Control used the CalTOX model to define the boundaries between these classifications. Using a hypothetical exposure scenario, department staff ran the model and then set threshold concentrations so that acute toxicity limits would not be exceeded. Much of the controversy centers on the distinction between the nonhazardous waste category and managed industrial waste. A scenario of residents living on a poorly capped landfill was used to set the boundary between these categories. The issue here is not the model, but the assumptions being used, said Chevron chemical engineer Mark Luce, who advises the Western States Petroleum Association. The boundary separating the nonhazardous category from the intermediate category
has particularly irked industry, which believes that the boundary is based on "a completely implausible scenario," Luce said. He contends that such a scenario is a thing of the past because landfills are highly regulated by the state. State staff counter that because such situations have occurred in
"Values and policy decisions are hiding behind the science." —Caryn Woodhouse, Toxics Assessment Group the past, they could occur again in the future; therefore, modeling this worst-case scenario protects public health. Environmental groups also question the assumptions used in the modeling. "Values and policy decisions are hiding behind the science," said environmental consultant Caryn Woodhouse of Taylor Bay Associates, who represents the citizens' Toxics Assessment Group in Davis, Calif. According to Woodhouse, the proposed classification system would, for example, allow much higher concentrations of lead to go unregulated but set tighter limits on dioxin. CalTOX developer Tom McKone
of the University of CaliforniaBerkeley sees the California debate as an important aspect of improving risk assessment. "CalTOX is a great tool for understanding die big picture, so it is well suited for classifying waste for potential exposure. But someone still has to make assumptions about the scenarios. It is easy to the likelihood tiiat people will live in a certain place and to mix these likelihoods together but that is a policy decision " he said Jim Carlisle, senior toxicologist with the Department of Toxic Substance Control who is supervising the classification revision, believes that criticism of die new system is as much about diis type of policy decision as it is about science. "We've reached the limits of our ability to resolve the issue," he said. "We can tell policy makers what happens if people live on a landfill, but we can't work out the likelihood." Carlisle is working to revise die draft regulations by January. Meanwhile, the National Academy of Sciences has agreed to a year-long review of die use of CalTOX in California's proposed waste classification scheme, which will be completed in late 1998. But observers fear that by focusing on the scientific issues, the review will fail to resolve the controversy. —REBECCA RENNER
New RBCA standard for chemical waste cleanups developed by ASTM Following the success of its "riskbased corrective action" (RBCA) standard for petroleum-contaminated sites, the American Society for Testing and Materials (ASTM) is expected to put into effect a provisional standard for chemical-contaminated sites this month. The RBCA standard for petroleum-contaminated sites has been incorporated into many states' remediation programs. The new standard, called "RBCA 2," was approved at the society's recent meeting in San Diego. The Committee for Environmental Assessments will vote on formally adopting the standard widiin the
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next two years. The RBCA process bases cleanup actions on an assessment of the risk chemicals pose to human health and the environment and on the planned future use of the site. The provisional standard will give site owners more certainty in terms of acceptable cleanup levels, said Mike Italiano, executive director of the RBCA Leadership Council, a Washington, D.C.-based trade association. Like the petroleum cleanup standard, RBCA 2 uses a threetiered approach to determine the amount of testing required at the site and the level of contamina-
