ENVIRONMENTAL NEWS U.N. negotiations on POPs snag on malaria
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t the third round of international treaty negotiations on persistent organic pollutants (POPs) held in Geneva, Switzerland, in September, 115 countries agreed to limit DDT for use in indoor spraying only. If the draft text survives the next two negotiation rounds scheduled in 2000, total DDT elimination will be postponed until safer, cost-effective alternatives have been found. The goal of the United Nations treaty is to reduce or eliminate 12 particularly hazardous chemicals—including eight pesticides, two industrial chemicals, and two unintended combustion and industrial byproducts (ES&T 1998, 3 (9), 394A-395A). Although the eight least produced and used POPs are slated for elimination with some limited, country-specific exemptions, polychlorinated biphenyls (PCBs), dioxins, furans,
Some 2.5 billion people in more than 90 countries are currently at risk of contracting malaria. The World Wildlife Fund estimates that malaria causes 500 million acute clinical cases and kills 3 million people annually.
"Under some circumstances, DDT is still the best available weapon against malaria," despite the fact that "an awful lot of mosquitoes, some as early as the 1950s, have developed resistance to DDT," said Anne Piatt McGinn, senior researcher at the Worldwatch Institute. Areas in southeast Asia are well known for DDT resistance. Some lowercost DDT alternatives include bed nets treated with synthetic pyrethroids and integrated pest management, said Clifton Curtis, director of the World Wildlife Fund's global toxic initiative. But research and funding limitations have prevented their widespread expansion.
and DDT proved to be the more controversial POPs chemicals tackled at the Geneva talks. DDT's usefulness and relatively low cost in combating malaria stymied negotiators at the talks' outset.
Roughly 30 countries still use DDT, the bulk of them in Africa, said Piatt McGinn, adding that only six countries are still producing it, with global production capacity estimated at 35,000 metric tons in 1995. But improperly
TABLE 1 Production and use of 12 persistent organic pollutants POP
Date started
Cumulative world production (tons)
Designed use
DDT
1942
2.8-3 million
Domestic and agricultural insecticide against mosquitoes
Aldrin
1950
240,000
Insecticide to control soil pests (primarily termites) on corn and potatoes; fumigant
Dieldrin
1950
240,000
Insecticide used on fruit, soil, and seeds
Chlordane
1947
70,000
Insecticide used in fire ant control and on a variety of crops
Heptachlor
1952
no data
Insecticide in seed grain and crops; termiticide; used for fire ant control
Hexachlorobenzene
1945
1-2 million
Used as fungicide; also a byproduct in pesticide manufacture and contaminant in omer pesucide products
Mirex
1959
no data
Insecticide and fire retardant
Toxaphene
1948
1.33 million
I11. ir-Gl .iciUG, e s p e c i a l l y a g a i U o l UUlvb, [ l l l l c b , H i c i g g u i o , u b c d o l l lA.'tlUn
r vDo
1 *j£-\J
1-2 million
Used as weainerproofers, hydraunc lIC]uiQS in transformers, IICJUIO insulators, dielectrics, and to prolong residual activity of pesticides
Endrin
Rodenticide and insecticide used on cotton, rice, and maize
Dioxins
Byproduct of combustion—especially plastics—and of chlorine product manufacture and paper production
Furans
myproduct, often bonded t o d i u x i n s
Source: WorldWatch Institute, 1999.
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© 1999 American Chemical Society
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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