Environmental t News Acetaminophen forms toxics during chlorination
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by variations in the volume of the wastewater influent) may lead to a buildup of these compounds in the treatment plant, he says. NAPQI is a known hepatotoxin. It is also generated in the human body during acetaminophen metabolism and can be responsible for lethality in overdoses of the drug. 1,4-Benzoquinone, a hydrolysis product of NAPQI, is a benzene metabolite suspected of causing genotoxic and mutagenic effects. In fact, acetominophen’s potential transformation to toxic products triggered Bedner’s interest in the drug’s behavior during wastewater treatment. “Acetaminophen is so common these days, since it is added to all sorts of sinus and cold medicines,” she says, adding “but it also has this dark side to its oxidation chemistry that we don’t usually acknowledge.” “This paper provides a good example of why we should consider disinfection chemistry when we evaluate pollutant fate during municipal wastewater treatment,” says environmental chemist Michael Dodd, who is with the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and has investigated the reactions of chlorine and ozone with a number of antibacterial agents. We are just beginning the second phase in the study of pharmaceuticals, says Sedlak, who draws parallels to the history of pesticide research. Now that researchers have determined the occurrence of the parent compounds, they can begin to investigate potential reaction products, especially those that could be more toxic or stable than the parent compounds. —ANKE SCHAEFER PHOTODISC
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cetaminophen, the most “This is one of the first papers widely used painkiller in that details the products of chlothe world and the active inrine reaction of a pharmaceutical,” gredient in over-the-counter drugs says David Sedlak of the civil and like Tylenol, may be transformed environmental engineering deinto toxic compounds during chlopartment at the University of Calirination in wastewater treatment fornia, Berkeley. He stresses the plants, according to research pubimportance of studying the reaclished in this issue of ES&T (pp tion products of pharmaceuticals 516–522). The occurrence of pharmaceuticals in the environment has received a lot of interest following a study by the U.S. Geological Survey (USGS; Environ. Sci. Technol. 2002, 36, 1202–1211), but little is known about their potential transformation during wastewater and drinking-water treatment. According to the USGS study, acetaminophen, which is also known as paracetamol, Oxidation of pharmaceuticals during wastewater is one of the most frequently chlorination can lead to worrisome byproducts. detected anthropogenic compounds in streams in the U.S. more closely, because they can be Chlorination is the most more toxic or more stable than the common chemical method for parent compounds. “Otherwise, wastewater and drinking-water when looking at pharmaceuticals disinfection in the U.S. Under conin the environment, we may simditions simulating wastewater disply not be looking at the right cominfection, acetaminophen reacted pounds,” Sedlak says. He predicts with hypochlorite to form a varithat this type of reaction will also ety of products, two of which were play a role in other disinfection identified as toxic compounds— techniques, such as ozonation or 1,4-benzoquinone and N-acetyl-preaction with chloramines. benzoquinone imine (NAPQI)—by It would be interesting to see authors Mary Bedner and William whether 1,4-benzoquinone and MacCrehan of the U.S. National NAPQI can be measured in real Institute of Standards and Techwastewater treatment plants, says nology. After a 1-hour treatment Bedner, who acknowledges that with 4 milligrams per liter (mg/ these compounds are not very staL) of chlorine, these byproducts ble and, therefore, are unlikely to comprised 25% and 1.5% of the persist in the environment. They initial acetaminophen concentracould nonetheless have an ecotion, respectively. Typical chlorine logical impact downstream of the concentrations used in wastewatreatment area in effluent-domiter chlorination range from 2 to 10 nated environments, Sedlak says. mg/L, with a usual contact time of In addition, changes in the dose 5 minutes to 1 hour. of chlorine (which can be caused
© 2006 American Chemical Society
Joan Thullen, USGS
Havens for wildlife in the parched southwestern U.S., wetlands constructed to receive sewage treatment plant discharges also boast a sterling record for slashing nutrient levels, suspended solids, and biological oxygen demand in effluents. But after two decades of research on treatment wetlands, scientists have scarcely investigated whether pesticides and metals in sewage effluent pose a risk to wildlife. Research published in this issue of ES&T (pp 603–611) indicates for the first time a potential exposure pathway for a complex mix of the nearly 50 inorganic and organic contaminants found in a treatment wetland. Larry Barber and his colleagues at the U.S. Geological Survey (USGS) analyzed water and fish tissue samples from the Tres Rios Demonstration Constructed Wetlands located near Phoenix, Ariz. The 10-acre site receives secondary sewage effluent from industrial, residential,
Treatment wetlands outperform sewage treatment plants when it comes to removing contaminants, but scientists say that exposure to 100% effluent could pose risks to wildlife health.
and medical sources. Contaminants flowing through the site are eliminated through photodegradation, volatilization, biodegradation, sorption to sediments, and uptake by plants, says Barber. Indeed, the researchers found that the wetlands reduced contaminant concentrations by 40– 99% between the inlet and outlet. Nonetheless, tilapia fish living in the wetland (to control mosquitoes) accumulated levels of the DDT degradation product, p,pDDE, at concentrations as high as 870 micrograms per kilogram (µg/kg) body weight, whereas mosquito fish took up as much as 1300 µg/kg. Similarly, tilapia stored the pesticide trans-nonachlor at levels up to 670 µg/kg, and mosquito fish had levels as high as 1800 µg/kg. Levels of some chemicals, such as p,p-DDE, increased in the wetland because they were released from the soils on which the wetland was built, say the researchers. These levels are higher than values reported for other water bodies less impacted by wastewater, Barber says. In addition to their toxic properties, p,p-DDE and trans-nonachlor are endocrine disrupters. “Based on the results from other studies, the chemistry data indicate that exposure to the levels of endocrine disrupting chemicals in the effluent may affect the reproductive health of the fish,” he says. Although the Tres Rios fish populations appear to be healthy and robust, a fish consumption advisory exists for a nearby stream that receives the same effluent as the wetlands, he notes. The high levels of bioaccumulated toxins could be a concern for some of the wildlife, such as herons that eat the fish, says Roland Wass, a coauthor of the study and president of Wass Gerke and Associates.
News Briefs Controlling allergens improves asthma
A home-based intervention program aimed at reducing dust mites, cockroaches, mold, and secondhand smoke not only reduced asthma symptoms but also cut the cost of treating children with mild to severe asthma, according to new research published in the Journal of Allergy and Clinical Immunology (doi 10.1016/ j.jaci.2005.07.032). The parents of more than 900 participants, ages 5–11, living in low-income sections of 7 urban cities, received instructions for reducing allergens inside the home. According to lead researcher Meyer Kattan, a pediatric pulmo nologist with the Mount Sinai School of Medicine, and colleagues, the kids experienced 19% fewer unscheduled clinic visits and a 13% reduction in the use of albuterol inhalers. The researchers calculated that the intervention also produced 37.8 more symptom-free days over 2 years.
Making H2O2 greener
Researchers at the U.S. Department of Energy’s Idaho National Laboratory reported in October that they have discovered a way to improve the utility of hydrogen peroxide (H2O2 ) as an environmentally benign agent for industrial processes. The new technology relies upon an enzyme produced by an extremophile bacterium, Thermus brockianus. It has a much longer industrial half-life than comparable commercial catalases—15 days rather than 15 seconds. The enzyme is able to remove H2O2 by breaking it down after it has been used to treat wastewater. H2O2 is increasingly being used to eliminate bacteria on fresh produce and for pasteurizing dairy products and sterilizing food packages.
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Engineered wetlands may pose risks to wildlife
Environmentalt News Therefore, a full-scale 450-acre treatment wetland that the city of Phoenix and the U.S. Army Corps of Engineers plan to build at the demonstration site will have a fish-free basin at the upstream end. Eventually, much cleaner water will be delivered to a downstream wetland basin with fish and will enhance habitats along the Salt River, he says. By restricting fish to the basin with lower contaminant levels, the researchers hope to minimize any ecological risks due to bioaccumulated toxins. “The study doesn’t tell us anything about the health of the fish
that they sampled—such as were they healthy, reproducing animals or were they sickly animals on their last legs, and whether or not they showed signs of stress from living in this ‘nitrified’ secondary effluent,” says Bob Bastian, a senior environmental scientist in the U.S. EPA’s Office of Water. Because wetlands are so rare in the Southwest, the artificial treatment wetlands could benefit wildlife by increasing their food supply, despite exposing fish and their predators to risks associated with bioaccumulation of contaminants, he says.
Lead a hazard in post-Katrina sludge trations of aeromonas bacteria as high as 26 million colony-forming units per milliliter (CFU/mL), more than twice the expected range of 100 to 10 million CFU/mL in polluted water. Some species of aeromonas are an emerging threat to human health and have been isolated from nearly one-quarter of infected wounds from tsunami survivors in Thailand, he says. “The most concerning findings are the elevated lead concentrations in the soil, because children
on playgrounds don’t wash their hands and [they] put everything in their mouths, which predisposes them to lead exposure,” Presley says. At 2 out of 12 sites, the researchers measured lead concentrations of 405.5 parts per million (ppm) and 642 ppm, exceeding EPA’s soil cleanup standard of 400 ppm. The crusty sediment and sludge layer, up to several inches thick, readily becomes airborne dust when disturbed, presenting a risk of exposure through inhalation, he says. Presley and his colleagues are probably finding at least some lead S. M. PRESLE Y
When Hurricane Katrina’s floodwaters receded, they left behind a chocolate-malt-like coating of sediment and sludge on the yards, homes, and cars of New Orleans. Research published in this issue of ES&T (pp 468–474) provides one of the first peer-reviewed analyses of contaminants in the sediment; it is based on samples taken just 2 weeks after Katrina’s August 29 strike. The findings reveal troubling levels of lead that, when considered alongside historic soil contamination, call for remediation, some scientists say. Steve Presley and his colleagues at Texas Tech University collected sediment and soil samples from September 16 to 18 along a transect bisecting the city from the high ground of the French Quarter to the lowlands at Lake Pontchartrain. The researchers analyzed the samples for 26 metals and 90 compounds, such as pesticides. They also tested floodwaters for three kinds of disease-causing bacteria. Concentrations of lead, arsenic, the pesticide aldrin, and eight other organic compounds in some of the samples exceeded the U.S. EPA’s thresholds for human health and soil cleanup, Presley says. The researchers also found concen-
Treatment wetlands have already proven themselves to be incalculable assets in the arid southwest, not a liability, says Christie Moon Crother, a geologist with California’s Eastern Municipal Water District in the San Jacinto Valley. Nearly 120 bird species visit the district’s treatment wetland, including the once-declining white-faced ibis, which avoided Endangered Species Act listing after its population rebounded on the abundant nesting sites and food created by this wastewaterfed, engineered wetland, she says. —JANET PELLEY
When the Texas Tech University team drove through New Orleans to take samples, their truck raised a cloud of dust from the sediments displaced by the flood.
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a decline in intellectual ability and erratic behavior. Lead poisoning has also been linked to criminal activity in teenagers, he says. EPA’s soil cleanup standard of “400 ppm lead is totally out of range with what a child can safely be exposed to,” Mielke adds. The European standards for soils, 40– 80 ppm, and Canadian standards, 150 ppm, are far lower than the U.S. threshold, he says. What EPA officials are saying officially is that the Texas Tech findings are an important independent confirmation of the sampling done by the agency. “Being above 400 ppm lead in an urban environment is not particularly unusual,” says Bill Farland, EPA’s acting deputy assistant administrator for science. —JANET PELLEY
For close to a decade, the federal government has recommended that workers use lead-specific cleaning products or the harsh detergent trisodium phosphate to clean houses contaminated with lead dust. However, scientists never adequately checked to see whether special cleaning agents were actually needed. Research published in this issue of ES&T (pp 590–594) reports that any general cleaner will effectively remove lead-contaminated dust. In response, the federal government plans to change its lead abatement guidelines, which will slightly lower cleaning costs and help keep environmentally unfriendly phosphate products from entering the environment. “Our study found that there is really no difference between all the different types of cleaners,” says the study’s lead author Roger Lewis, director of the environmental health research lab at St. Louis University’s School of Public Health. “The problem now is that we need to disseminate this information.”
mickey smith
Household cleaners can remove lead dust
Windowsills are prime sources of lead paint in older houses.
Lead has been shown to cause neurological problems in young children. In the 1990s, the U.S. Department of Housing and Urban Development (HUD) established guidelines on reducing hazards from exposure to leadbased paints, says Peter Ashley, an environmental scientist with the agency. “Most of the work being done doesn’t involve paint removal; it’s normally just stabilizing the paint in place,” says Ashley. On the basis of the best avail-
News Briefs Record renewable growth
Global investments in renewable energy—excluding large hydropower—rose to a record $30 billion in 2004, compared with $150 billion in investments in the conventional power sector, according to a new report by the Renewable Energy Policy Network for the 21st Century (REN21), a global policy network. Overall, small hydro, biomass, wind, solar, geothermal, and biofuels accounted for 160 gigawatts, making up about 4% of global power sector capacity. Nearly half that amount was generated in developing countries, the report finds. Large hy dropower attracted an additional $20–25 billion in investments in 2004, primarily in developing countries, and comprised 16% of global electricity generation. Grid-connected solar photovoltaic is the fastest-growing energy technology worldwide, with capacity increasing by 60% annually from 2000 to 2004, the REN21 assessment concludes. Wind power came in second, growing by 28% per year.
… and renewable power purchases are rising
Renewable energy capacity serving green power markets in the U.S. now tops 2200 megawatts, a 10-fold increase in 5 years, according to a new report from the U.S. National Renewable Energy Laboratory (NREL). The growth is driven primarily by nonresidential customers such as government agencies, businesses, and universities looking to meet environmental goals. Green power programs offered by electric utilities allow customers to purchase some portion of their power supply—usually at a higher price—from renewable energy sources. The renewable sources most commonly tapped by utilities are wind, solar, and landfill gas, NREL finds. Wind energy makes up the largest portion of total capacity.
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contamination that existed before Katrina flooded New Orleans, says Howard Mielke, an environmental toxicologist at Xavier University. Before Katrina, Mielke analyzed nearly 5000 soil samples from across the city and revealed that 40% of New Orleans soils exceed the lead cleanup standard, with some lead concentrations above 1000 ppm. Lead sources include historic use of leaded gas, lead paint, and emissions from now-mothballed garbage incinerators, he says. As a result, even before Hurricane Katrina, 20–30% of children in the inner city were suffering from lead poisoning, with blood lead levels greater than the Centers for Disease Control and Prevention’s health guideline of 10 micrograms per deciliter (µg/dL), Mielke says. Lead poisoning symptoms include
Environmentalt News able evidence, HUD recommended the use of lead-specific cleaning agents or trisodium phosphate. “It wasn’t a requirement, but the guidelines carried weight and became the de facto procedures for contractors carrying out work,” he says. In fact, these guidelines are now being followed in cities, counties, and states across the U.S. For the study, Lewis and colleagues tested how well various detergents removed lead dust from three different building materials: linoleum, wallpaper, and pine veneer. First, lead dust was embedded into the material at levels typically found in older U.S. houses. The lead concentration in the dust was 20 milligrams per cubic meter. To ensure a uniform pressure while cleaning, the researchers used a robotic arm to wipe
the surface. While finding that no detergent worked better than any other, the authors also discovered that linoleum and pine veneer were easier to clean. Ashley says that his agency funded the study to test the efficiency of different products and because phosphate cleaners are known to cause algal blooms after they wash into streams and rivers. He says that not using phosphate cleaners in the first place is the best way to ensure that they don’t become a problem in the environment. “The EPA allows lead hazard control work to be treated as regular construction debris,” says Ashley. “So it doesn’t have to be handled as a hazardous waste.” Ashley says that new HUD guidelines to be released in the
next few months will no longer recommend either phosphate detergent or lead-specific cleaning agents. Lewis says that the use of lead-specific cleaning agents has created a cottage industry for products that seem to perform no better than those you might already find under your kitchen sink. Switching to regular household products probably won’t save a great deal on total construction, but lead-specific cleaners can cost 4–5 times more than products that can be picked up from the local market. “People are making money selling this stuff, but there’s no proof it works,” Lewis says. Noting that he could not find any studies backing up the claims that these cleaners actually work, he added, “Let’s see their data.” —PAUL D. THACKER
After 25 years, the U.S. EPA has recommended that state and local regulators use a new air-quality model as of December 9, according to a notice published in the Federal Register (2005, 70, 68,218– 68,261). The AERMOD model is being phased in as the tool that regulators use for assessing their progress in reducing criteria air pollutants under the Clean Air Act (CAA). AERMOD was designed to meet requirements identified by a committee that included scientists from EPA and the American Meteorological Society (AMS). The committee’s charge was to “introduce state-of-the-art modeling concepts into the EPA’s local-scale air-quality models,” according to the agency’s website. AERMOD is a steady-state plume model that incorporates air dispersion on the basis of planetary boundary-layer turbulence structure and scaling concepts. According to the Federal Register, AERMOD “provides better characterization of plume disper-
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EPA updates air-quality model
Use of the model could lead to relaxed restrictions for some manufacturers.
sion than” Industrial Source Complex (ISC3), which has been EPA’s preferred model since 1980. AERMOD is able to simulate elevated air pollution sources as well as those at the surface, and it can incorporate both simple and complex terrain. On November 9, 2006, AERMOD will replace ISC3 as the agency’s “preferred general-purpose” model. At that time, it will become the model that regulators use to estimate local levels of ozone, volatile organic compounds, carbon monoxide, NO2, SO2, particulate matter, and lead. Areas that have been
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unable to attain CAA standards for these criteria pollutants will be required to use AERMOD to revise their State Implementation Plans for existing air pollution sources. States will also need to use AERMOD for their New Source Review and Prevention of Significant Deterioration programs. AERMOD’s predictions of ground-level pollutant concentrations are more accurate because they incorporate up-to-date physics to simulate air emissions plume transport and dispersion, says Rob ert Paine, technical director of ENSR, an international environmental services company. Paine was a member of EPA’s AERMOD design team. “In many cases, AERMOD predicts lower concentrations than the ISC[3] model,” he adds. This means that some facilities’ operational restrictions may be relaxed, he explains. The agency’s peer-review process verified that the AERMOD model is widely considered to represent the “state of the science” and confirmed that it “represents sound and significant advances over” ISC3, according to the notice. —KELLYN S. BETTS
