stored chemical stockpiles of this and other POPs in developing countries pose huge environmental and health risks. "These stockpiles are actually more like hazardous waste sites," said Jim Willis, head of the United Nations Environment Programme's (UNEP's) chemical division and the meeting's secretary. "In Africa alone, there are probably at least 1000 [metric] tons of POPs pesticides." Financial assistance for developing countries and political pressure ultimately will determine the treaty's success in eliminating or reducing existing stocks of all the POP chemicals. These negotiations "have really brought this issue to a head, crystallizing the need for funding of alternatives," Piatt McGinn said. With dioxins and furans, European countries initially recommended a more precautionary approach than the United States, but as the talks progressed, a consensus was being reached on reducing releases of these chemicals rather than eliminating them. "The problem with the aim to eliminate is that these two byproducts are almost everywhere," said a U.S. State Department source. Technologically, it is not clear at this point that elimination is even possible he noted Adding to the problem, few countries monitor the amounts of dioxins and furans they release into the environment, and even among those countries that do measure, the data are widely variable, Willis said. A recent UNEP survey, to which only 15 countries replied, estimated global dioxin emissions at roughly 10 kilograms annually. As for PCBs, countries agreed to eliminate new use and production, but not to destroy existing stocks because of their ubiquitousness. "Even countries such as Sweden who have undertaken really massive efforts to try to get all the PCBs out of the country found that some uses were not economically feasible to eliminate," Willis said. These issues, as well as developing scientific criteria and a process for adding new chemicals to the treaty, remain on the table for further negotiation at the next two rounds of treaty talks in 2000. —KRIS CHRISTEN
CLIMATE Understanding global water cycle is key to managing climate change, NRC reports Although most climate scientists agree that understanding the earth's water cycle is key to managing global climate changes, critical research areas are being overlooked by the U.S. Global Change Research Program (USGCRP), according to the National Research Council (NRC). The panel notes that in the most recent USGCRP implementation plan for the 2000 fiscal year, Our Changing Planet, the global water cycle was listed as one of six fundamental program elements. The 47-page report is the first in a series from NRC's newly established Committee on Hydrologic Science. The panel makes three conclusions: • Several priority areas, particularly with respect to detecting and predicting changes to the water cycle, are not well developed within the USGCRP. • Satellite measurement programs, which constitute more than 70% of the program's water cycle budget in the current fiscal year, are not designed to meet the challenges presented in the most recent implementation plan. • Water resource management issues, such as decision making under drought conditions, should be an integral component of the program and "help guide the evolution of new initiatives within the USGCRP." The panel also noted the importance of educating decision makers, and students as early as kindergarten, on water resources in a changing world. And the scientific community should begin to share knowledge and scientific tools with water managers and engineers, NRC wrote. For a copy of Hydrologic Science Priorities for the U.S. Global Change eesearch Program: An Initial Assessment, call (202) 334-2138. —C.M.C.
EPA charts new course in draft cumulative risk assessment for pesticides The first draft of EPA's cumulative risk assessment method for pesticides was met with approval from an independent Science Advisory Panel (SAP), although the group had plenty of advice on how to improve things. In September, the SAP reviewed two methods for determining whether the toxicity of several pesticides overlaps. Crafted by EPA's Office of Pesticide Programs (OPP), the methods will guide risk assessors who must meet the new demands of the Food Quality Protection Act (FQPA). The 1996 law, passed unanimously by Congress, requires EPA to revise residue tolerances for pesticides and set new tolerances that identify a "safe" level of pesticide exposure. For the first time EPA must consider a person's cumulative chemicals that have a common mechanism of toxicitv The OPP team stressed the preliminary nature of its work, for good reason. By developing such a complex method, EPA is undertak-
ing work that no risk professional has actually completed for publication, although a few have worked on components of cumulative risk, several risk experts said. A few pharmaceutical companies are working with cumulative risk, but the companies are not sharing the results of their work. The OPP's proposed methods were illustrated by a case study of organophosphates, a class of chemicals widely used by farmers and homeowners. The two methods first calculate a margin of exposure (MOE) for each chemical. EPA defines an MOE as the ratio of a dose that relates to a specific toxic effect to the human exposure level. The larger the ratio, the lower the risk. The MOE is incorporated into two methods: the Relative Potency Factor MOE and the Cumulative MOE The SAP questioned EPA on its choice of endpoints, how and why it chose certain points of departure, and how it would combine its toxicity data. The group suggested that EPA add real-world data on
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interactions and expand the case study to other chemical groups. They pointed out that with so little available data on chemical interactions and toxicity effects, EPA will end up inserting a large number of assumptions into its analysis. How OPP chose its assumptions was not clearly articulated, the panel members said. The proposed methods may be too limited to meet the requirements of the FQPA, other risk professionals said. The approaches are useful if used as a screening tool to determine which chemicals are potentially of concern, said Resha Putzrath, principal toxicologist for Georgetown Risk Group in Washington, D.C. "To do the next step, to find out [more accurately] if they really are of concern requires an
incredible amount of data and work," said Putzrath. One large data gap deals with exposure. EPA officials agree that gathering exposure information is a big hurdle they have not tackled. This is particularly true for residential exposure, said Beth Doyle, a toxicologist in OPP. Agency officials are determining what information they need and how they will collect it, and are likely to unveil their plans for this in December. At the same meeting, the OPP team will submit the exposure portion of its risk assessment to the SAP she said This complex approach to risk assessment disappoints consumer and environmental groups, who believe that devising a method that is on the cutting edge will slow down, if not stop, the
issuance of revised tolerances. If the data are not available to support a cumulative risk assessment, the FQPA requires EPA to issue new tolerances using a 10-fold safety factor, said Charles Benbrook, a consultant with Consumers Union, headquartered in Yonkers, N.Y. "To do a crude cumulative risk assessment is not that difficult," said Benbrook. A coalition has already sued EPA for not revising tolerances by the FQPA deadline. A schematic outlining the general cumulative risk assessment process is found on pELSC 12 of OPP's document "Proposed Guidance on Cumulative Risk Assessment of Pesticide Chemicals That Have a Common Mechanism ofTfmrilv" found 'At www^nM unv/ Desticides/SAP/ 1999/index htm CATHERINE M. COONEY
Long-dormant Clean Water Act provision strengthened After some 30 lawsuits filed by environmentalists nationwide, EPA released a long-awaited proposal in August strengthening the Clean Water Act's (CWA's) Section 303(d), which requires states to list impaired waterways and develop total maximum daily load (TMDL) allocations [Fed. Regist. 1999, 64 (162), 46,011-46,055). TMDLs, designed to help states determine how much various pollutants must be reduced to meet water quality standards in a given waterway, have been part of the CWA since its inception in 1972. But states and EPA have failed to enforce this program, environmentalists have charged, and courts largely have agreed. The proposed rule clarifies requirements regarding how impaired waters should be listed and how TMDLs should be established, said Don Brady, chief of EPA's Watershed Branch. Key components would require states to submit detailed TMDL implementation plans and timetables, along with their biennial listing of impaired waters. Moreover, states would set caps on pollution entering a given water body from point sources such as factories or wastewater treatment plants and also nonpoint pollutants
The 1998 Section 303(d) lists, required under the Clean Water Act, identified more than 300,000 river and shore miles and 5 million lake acres as polluted.
such as air deposition and agricultural and urban runoff. Environmentalists lauded the proposed revisions as "a step in the right direction." But the proposal drew mixed reviews from states, the Association of Metropolitan Sewerage Agencies, which represents wastewater treatment facilities, and the Association of State and Interstate Water Pollution Control Administrators, which represents state water program manag-
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ers. The American Farm Bureau Federation filed a lawsuit. "We don't like the fact that TMDLs are bringing in nonpoint sources because we don't believe the authority exists under the CWA for [EPA] to do that," said David Salmonsen, the Farm Bureau's director of governmental relations. The Farm Bureau hopes to keep regulation of nonpoint source pollutants under voluntary, incentive-based programs
