EnvironmentalM Ne causing all water to be recycled to some extent. As demand increases, Sakaji says, the percentage of water by wastewater effluent, he says. that is “of wastewater origin”—and Formation is maximized at the 6–9 the catalyst for the formation of pH range typically found in drinkNDMA—also increases. ing water treatment plants. Approximately 30% of U.S. The research “is a real strong indrinking water utilities use chlordicator that we do have a new disamines, which contain chlorine and infection byproduct,” says Rick ammonia, says Bill Lauer, an engiSakaji of the California Department neer at the American Water Works Association, a nonprofit organization of drinking water providers. Because monochloramine is the chloramine that is considered to be the most effective for disinfecting water, most utilities try to maximize their concentrations of it, he explains, noting that the actual amounts of monochloramine are dependent upon water characteristics like temperature and pH. Utilities are increasingly moving to chloramines as a disinfection agent to avoid the toxic byproducts associated with chlorine. To environmentalists, the new research is an indication that tinkering at the margins with products containing chlorine is not the best possible solution to dealing with New evidence show sthatNDM A,a probable the reality that disinfecting drinking human carcinogen,mayform in drinking w ater water can cause collateral health treated w ith chloramines.Scientistsare inves- damage, says Erik Olson, senior attigating w hethercommunitiesthatgettheir torney for the Natural Resources drinking w aterfrom riverscontaining excess Defense Council, a nonprofit envinitrogen due to runofffrom agriculturalland ronmental group. He acknowledges are atan increased risk. that products like chloramines are of Health Services. “It could be a big part of an important interim step to deal,” agrees Richard Valentine, a reduce overall disinfection byprodprofessor of civil and environmental ucts and suppress some of the worst engineering at the University of known byproducts. Iowa who is also studying NDMA Over the long term, however, formation in drinking water. “The Olson says, “the real answer, in our whole area is a classic example of view, is to shift to newer technolopeople not looking at the right gies or better technologies that replace, under the right conditions, at move precursors, so you’re not the right time,” he adds. creating this wide array of byprod“We’ve always considered ucts, or to look at something like NDMA to potentially be a disinfecUV light, which apparently creates tion byproduct,” Sakaji stresses. The no byproducts.” root cause of the problem, he hyThe next important step in dealpothesizes, is increasing pressure ing with NDMA as a potential dison the nation’s waters, which is infection byproduct is to determine
isinfecting water with monochloramine may produce toxic byproducts, according to new research published in the February 15 issue of ES&T (Environ. Sci. Technol. 2002, 36, 588–595). The research is causing concern in the drinking water community because monochloramine’s main appeal as a disinfectant is to avoid the toxic byproducts associated with using elemental chlorine to treat water. The new research suggests that N-nitrosodimethylamine (NDMA), which is considered a probable human carcinogen, can be formed in surface water that is treated with monochloramine. The research confirms what researchers have observed in the field, says David Sedlak, an associate professor of civil and environmental engineering at the University of California–Berkeley. For more than 20 years, researchers have been aware that NDMA can form when drinking water is treated with chlorine under certain conditions, Sedlak explains. However, the exact conditions leading to NDMA formation were unknown. His laboratory studies have brought to light a series of chemical reactions showing how monochloramine could cause the toxic compound to be formed during the disinfection of drinking water. The research also implies that NDMA may be generated in water distribution systems, he says. Sedlak’s experiments show that NDMA is most likely to form in drinking water containing both monochloramine and dimethylamine, which is a common component of human and animal waste and can remain in water even after secondary wastewater treatment. For that reason, NDMA is most likely to be found in drinking water taken from surface waters impacted
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New drinking water hazard
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seen levels higher than 20 nanograms/liter (ng/L), the amount that California has set as a temporary action level. There are no federal standards for NDMA as yet, but the U.S. EPA’s Integrated Risk Information Service says levels higher than 0.7 ng/L result in an increased cancer risk. California was the first state to begin searching its drinking water supplies for NDMA in response to industrial contamination from rocket fuel production, Sedlak says. It soon became apparent that the compound was forming in reclaimed wastewater, he says. California’s experience shows that NDMA can be removed from drinking water via treatment with UV light, Sakaji says. The technology is currently being used in Southern California. Reverse osmosis is another treatment being investigated, he says, but it has not proven fully effective. In either case, the treatment is expensive, especially in light of the rapidly rising cost of electricity in the state, and wells have been closed because it is not economically feasible to treat the water, he says. —KELLYN S. BETTS
U.S. food agencies sponsor dioxin study
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Data from several independent tion in food, trends in human dioxstudies suggest that 95% of human in exposures, and options to reduce exposure to dioxin comes from dietary exposure to dioxin without food. That finding, along with compromising good health and nutougher new dioxin food standards trition. The panel is expected to in the European Union (see story issue its final report in spring 2003. on p. 95A), sparked enough conAt the panel’s first meeting on cern among officials with the two December 19, representatives from U.S. regulatory the two sponsoring agencies responsible agencies—the U.S. for food that they Department of Agriasked the National culture (USDA) and Academy of Scienthe Food and Drug ces (NAS) to study Administration the implications of (FDA)—emphasized dioxin in the U.S. the need to consider food supply. the trade-offs of variOver the next ous actions to reduce year, an NAS panel dioxin exposure. For will look at evidence example, an action for the presence of should not increase dioxin in foods, the cost of food to Recentstudiespointto food as pathways leading to the primaryroute ofdioxin expo- the point that people dioxin contaminacan no longer afford sure in humans.
Governm Computer manufacturing linked to cancers A study of cancer rates at a U.K. computer chip manufacturer found a “higher than expected” occurrence of four types of cancer. The results “raise the possibility of a work-related cause for some of these cancers,” according to the United Kingdom’s Health and Safety Executive, which conducted the study. The study, released in December, covered 4388 current and former employees of a plant run by the National Semiconductor Corporation in Greenock, Scotland. Using statistical analysis tools, the researchers determined that the female employees’ stomach cancer rates were 4−5 times higher than expected, and the male workers’ incidence of brain cancers was 4 times greater than the norm for the general population. The incidence of lung cancer for women who had worked at the plant was 2−3 times greater than for nonworkers, and their rate of breast cancer was elevated by 30%. However, the study’s findings are not considered conclusive because they do not include information about lifestyle factors. The Health and Safety Executive intends to conduct follow-up studies to evaluate a wider range of potentially germane factors, such as previous job histories, smoking, and diet. National Semiconductor, which pledged to support the additional investigation, issued a statement stressing that there is no proof that working at the company has caused an increased risk of developing cancer. The U.K. government was spurred to undertake the study by the International Campaign for Responsible Technology, a nonprofit group.
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how often it occurs, Valentine says. The American Water Works Association’s Research Foundation (AWWARF) and the Water Environment Federation are already funding a study to look for NDMA in drinking water throughout the United States, he says. In addition to chloramines, it appears that a number of drinking water treatment processes can contribute to NDMA formation by providing precursor material, he says. He credits his graduate student, Junghoon Choi, with discovering some mechanisms beyond the chloraminedimethylamine connection that Sedlak has elucidated. Some of the resins used for water treatment are nitrogenbased, so using them in conjunction with chloramines might cause NDMA formation, Valentine says. Midwestern water supplies that contain excess nitrogen as the result of agricultural practices may also be at risk, he adds. Valentine says that he has been finding NDMA concentrations at the parts-per-trillion level, which is near the detection limit for the compound. In some cases, he has
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committee administered by the Food and Agriculture Organization of the United Nations and the
World Health Organization, recommends a limit of 70 pg/kg bw/ month. —BRITT E. ERICKSON
Inspectors lack scientific arsenal to embargo invasive species The U.S. government’s screening models for invasive species are not adequate to protect the country from aggressive invaders, according to a new report by the National Research Council (NRC). The NRC’s report, Predicting Invasions of Nonindigenous Plants and Plant Pests, charges that the pest risk assessments used by the U.S. Department of Agriculture (USDA) to prevent the importation of invasive species are subjective, and the results are not reproducible or verifiable. Invasive foreign plants and animals cost the U.S. economy over $137 billion annually from lost crops and containment measure costs. They are the secondlargest driver of biodiversity loss, after habitat destruction, and can cause human illness, such as the mosquito-transmitted West Nile virus, says Lori Williams, executive director of the National Invasive Species Council, a federal coordinating body. The USDA’s Animal and Plant Health Inspection Service (APHIS) has the authority under the Plant Protection Act to prohibit importation of potentially invasive species, but international trade agreements stipulate that the decisions must be supported by scientific evidence and cannot impede trade. This mandate is a heavy burden, The Asian long-horned beegiven our limited knowledge of organisms and tle isa new and serious how they might behave in a new environment, threatto trees. says Dick Mack, ecologist at Washington State University and coauthor of the NRC report, which was released on Jan. 8. Undertaken at the request of APHIS, the NRC report concludes that there are currently no scientific principles or reliable procedures for identifying potential invasive species. However, the report presents a framework for developing a predictive system based on dozens of biological and environmental factors that foster invasiveness, such as a history of long-distance movement or uniparental reproduction. On the basis of the proposed framework, it is unlikely that the APHIS risk assessment captures the likelihood of invasion by an introduced species because it relies on only three risk elements, Mack says. The NRC report’s conclusions are not new, but their scientific credibility lends weight to efforts already under way to implement the report’s recommendations, Williams responds. —JANET PELLEY UDSA
good nutrition. The panel was urged not to rely on the U.S. EPA’s 11-year reassessment of the risks posed by 2,3,7,8-tetrachlorodibenzo-p-dioxin and related compounds, which has already been thoroughly reviewed. Dioxin levels in the environment have been declining since the early 1970s, according to William Farland, acting deputy assistant administrator for science in EPA’s Office of Research and Development. In addition, tissue data show that current dioxin levels in the U.S. population are declining and are about half of what they were in the 1980s, he says. Even so, the U.S. population is still being exposed to about 1 picogram of dioxin per kilogram of body weight per day (pg/kg bw/day), primarily through consumption of animal fat. Other recent re-evaluations of the toxicity of dioxin by the International Agency for Research on Cancer, the U.S. Agency for Toxicity Substances and Disease Registry, and the National Institute of Environmental Health Sciences also point to food as the primary route of dioxin exposure in humans. Although there are currently no dioxin tolerance limits in food in the United States, it could be part of a risk management strategy in the future, says James Schaub of USDA’s Office of Risk Assessment and Cost Benefit Analysis. USDA will investigate sources if meat or poultry is found to have unusually high levels of dioxin or if unusual congeners are found, he says. FDA is responsible for milk and dairy products. Monitoring of dioxin is expensive, however, and many laboratories are not equipped to perform such analyses. Researchers at USDA’s Agricultural Research Service in Fargo, N.D., are currently trying to develop lower-cost methods of monitoring dioxin. In the European Union, new dioxin food standards will go into effect in July 2002 (see story on p. 95A), setting the exposure limit at 14 pg/kg bw/week, and the Joint FAO/WHO Expert Committee on Food Additives, an international
Are national water quality assessments threatened? As the U.S. Geological Survey’s (USGS) National Water Quality Assessment (NAWQA) program moves from monitoring conditions to its second phase of assessing long-term trends, a report by the National Research Council (NRC) commends the program’s significant contribution to a better understanding of water quality nationwide. But the report notes that NAWQA has its work cut out
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for it in the upcoming decade. NAWQA’s biggest threat is funding shortfalls. “There’s a real concern as to whether they have the resources to do the job,” says George Hallberg, the report’s committee chair. NAWQA has been cut back from 59 water quality assessments in different geographical areas called study units in its first phase to 42 in the second because of funding constraints. If further
Federalfunding shortfallsthreaten w ater qualitystudies.
All in all, the NRC committee recommends that NAWQA “do more, not less,” but recognizes that current and future demands already exceed NAWQA’s capacity. “We all have to realize that to answer the long-term questions of what’s happening to our nation’s waters requires some long-term and consistent support,” Hallberg says. For more information, Opportunities To Improve the U.S. Geological Survey National Water Quality Assessment Program can be downloaded at www.nap.edu/ catalog/10267.html. —KRIS CHRISTEN
Mold growth linked to airtight building designs Although buildings are more airtight than they used to be, thanks to efforts to boost their energy efficiency, there’s a worrisome complication—in wet-climate and high-humidity areas, mold and mildew problems in these improved structures are on the rise. With the aid of powerful computer models, however, researchers are finding that the problem is not insoluble. The extent of the mold growth problem recently came to the attention of city officials in Seattle, Wash., where local architects and engineers rehabilitating buildings found that many buildings less than 10–15 years old were rotting from the inside out, says Michael Aoki-Kramer with the city’s
Governm
against an ecotoxicology program. “NAWQA’s forte is in collecting occurrence and field data,” Hallberg says, whereas ecotoxicology is more of a lab function.
EU limits dioxins in food and animal feed PHOTODISC
downsizing occurs, “we’d probably do away with the whole basis for trend analysis,” losing a decade worth of effort, Hallberg notes. NAWQA’s usefulness to various local, state, and federal agencies and other groups lies in the design consistency of each investigation and the use of standardized methods that make comparisons among the study units possible, according to the report. Many states are piggybacking their own programs onto NAWQA, building on the expertise and consistency in protocols developed under this program, an investment that’s often overlooked, Hallberg says. The NRC committee supports NAWQA’s existing priorities—which include measuring pesticides, nutrients, volatile organic compounds, and trace elements—and concurs with USGS proposals to add new contaminants—such as methyl mercury, waterborne microbial pathogens, pharmaceutical products, and high production volume industrial chemicals. The committee also strongly recommends that surface water sediments become a NAWQA priority topic and supports more biological assessments and ecological syntheses in surface waters, but it advises
Department of Design, Construction, and Land Use. “They hypothesized that with increased energy efficiency requirements, buildings were being made too tight and weren’t able to dry out.” A subsequent city survey of various multifamily buildings found that all of those built over the past 15 years had water leakage problems. Moreover, it didn’t seem to matter whether the wall system was brick, wood, vinyl, or stucco—they were all failing, says Jeff Christian of Oak Ridge National Laboratory (ORNL). Seattle officials teamed up with ORNL to tap into the lab’s expertise in assessing how well building materials respond to moisture over time. “We took 35 of the [Seattle] builders’ favorite wall systems and
Legally binding limits on dioxins in food and animal feed in the European Union (EU) will take effect this July. The limits—maximum thresholds for allowable dioxin levels—apply to all food and feed sold in the EU. The thresholds are the first part of a three-prong strategy targeting dioxins. Early next year, the European Commission (EU) is expected to define stricter action levels. Once approved by the EU Parliament and EU Council, they will require any member state finding food or feed containing dioxins above the specified levels to investigate contamination sources and take measures to eliminate them. Later next year, the EC will propose even tighter target levels to be achieved over the next five to six years. The EC’s overall plan is to reduce human daily intake of dioxins to
