Environmental t News More triclosan trouble
full risk–benefit analysis of these products should be conducted.” Three scientists, two of whom o longer just for hand soap, be used for household cleaning. work for a company that uses trithe antibacterial agent triExperiments with tap water from closan in its products, said that closan is cropping up in different locations yielded mixed in their opinion the results of the more and more consumer prodresults: little chloroform was gennew study should not be interucts. These days, even socks and erated in Atlanta water, but moderpreted too broadly; they chose not toothpaste aim to keep parts of ate levels formed in Danville, Va., to be quoted. Two said that the you microbe-free. But research water for some soaps. conditions used in the study, alpublished in this issue of ES&T (pp “At fairly low levels of chlorine, though more realistic than those 2387–2394) by Peter Vikesland and the triclosan degrades rapidly,” in previous work, do not necescolleagues at the Virginia PolyVikesland says. That speed leads sarily reflect normal exposure. technic Institute and State Unihim to ask whether triclosan is The researchers allowed reacversity shows that under normal broken down quickly enough in tions to proceed for 1 minute, but household conditions, prodcommonly used consumer ucts containing triclosan guidelines call for washreact with chlorinated waing hands for only about 15 ter to produce chloroform, a seconds. probable carcinogen. “I think even though In 2005, a bit of panic enthe actual washing condisued after ES&T published tions may vary among inVikesland’s research (Endividuals, the findings of viron. Sci. Technol. 2005, this study are still cred39, 3176–3185; 188A–189A; ible and very relevant be271A). The study showed cause of the conservative that in the laboratory, pure approach it took,” says Chtriclosan reacts with free ing-Hua Huang of the GeorTriclosan is found in an increasing number of antibactechlorine to produce chlogia Institute of Technology. rial consumer products. roform. Other news stoShe adds that the study ries followed, and soon Vikesland chlorinated tap water to render it used a “modest amount” of soap learned that stores in China were less effective in killing germs. (0.25 grams per liter of water) and removing triclosan-containing “I don’t find the formation of found large differences in chlotoothpaste from their shelves. In chloroform surprising; I think it roform concentrations with triresponse, Vikesland warned that will form under many scenarios in closan-containing (averaging 60 people should not jump to concluour daily lives,” says Shane Snyder micrograms per liter [μg/L]) and sions and pointed out that his work of the Southern Nevada Water Autriclosan-free (2 μg/L) soaps. did not examine toothpaste. thority. After the City of Palo Alto, Ciba Specialty Chemicals inThe team has now followed up Calif., banned triclosan-containvented triclosan 35 years ago, on that study and tested 16 proding soaps from city facilities, Snyaccording to the company’s webucts, including lotions, soaps, and der says he was contacted about site. Ciba officials do not dispute body washes with and without enacting a similar ban in the Las the formation of chloroform in triclosan. They found that all of Vegas area, but he saw no reason to the study but do question wheththe household goods with triclodo so from a wastewater-treatment er the researchers used realsan produced either chloroform perspective. Chlorine reacts with world conditions, says company or other chlorinated byproducts. various forms of organic matter in spokesperson Pat Rossman. Ciba From their tests, they estimate that municipal water to produce chloofficials point out that some chlounder some conditions, the use of roform, he says, and he expects the roform formed with triclosantriclosan can increase annual exlevels of chloroform from triclosan free soaps and that the tap-water posure to chloroform by as much to be negligible. studies show decomposition levas 40% above background levels in Triclosan creates enough chloels much lower than those obtap water. roform to warrant more study, tained under lab conditions. The In some soaps, all of the triclobelieves Vikesland, but he maincompany will review the findsan degraded within 1 minute of tains that “it’s hard to predict exings, Rossman says, and conduct exposure to chlorinated water at actly what’s going to happen at an further evaluations. 40 °C, a temperature that might individual’s tap.” He writes that “a —ERIKA ENGELHAUPT Pe ter Vikesl and
N
2072 n Environmental Science & Technology / APRIL 1, 2007
© 2007 American Chemical Society
News Briefs
Research published in this issue of ES&T (pp 2153–2158) uses an innovative approach to show that indoor air releases far more PCBs to the atmosphere around England’s second-largest city than does the area’s soil. The findings go against the widely held hypothesis that soil volatilization is the main source of PCBs in the environment, according to Stuart Harrad and his colleagues at the University of Birmingham (U.K.), where the measurements were made. The paper adds important new data to the growing body of research showing that older consumer products still in use are a significant source of PCBs on a global basis, says Terry Bidleman of Environment Canada’s Air Quality Processes Research Division. The ventilation of contaminated indoor air “to outside is what is driving outdoor air concentrations, which in turn is what drives food concentrations,” Harrad explains. At present, food is the main route through which most people are exposed to PCBs. The concentrations of nondioxin-like PCBs in U.K. food have not declined since 1992, according to a draft report by the country’s Department for Environment Food and Rural Affairs (Defra). It documents that concentrations of these nondioxin-like PCBs—which are primarily what Harrad’s group was monitoring— have increased in 9 out of 11 food groups monitored between 1992 and 2001. “This is not inconsistent with there being a continuing and nondiminishing source of PCBs to the environment that is helping to maintain concentrations in food,” Harrad says.
Harrad’s new data corroborate recent measurements of the sources of PCBs in and around Toronto, says Tom Harner, a research scientist with Environment Canada. “We now have two comprehensive studies that have investigated the plume of PCBs in urban areas, both implicating indoor air as the major source and both showing strong gradients as you move away from the most heavily populated areas,” Harner says. Harrad and his colleagues took the concept one step further than the Toronto study by distinguishing between sources of PCBs from indoor air and soils. To do so, they exploited the fact that some of the individual PCB compounds, or
A tasty antidote to lead poisoning
Help for the effects of lead poisoning on learning and memory may lie in the roots of Curcuma longa, the source of the Asian spice turmeric. That conclusion comes from a study published online January 17 in the Journal of Agricultural and Food Chemistry (2007, 55, 1039– 1044). Lead reduces levels of antioxidants—compounds that mop up toxic free radicals—in the brain. Free radicals kill neurons in the hippocampus, the brain region that controls learning and memory. When simultaneously treated with lead and curcumin—a powerful antioxidant in turmeric— rat hippocampal neurons survived better than those treated only with lead. Curcumin also improved the performance of lead-poisoned rats in a learning and memory test.
Top 10 refinery polluters
Researchers took samples from areas in and around Birmingham (U.K.).
congeners, are chiral molecules that have two nonsuperimposable mirror-image forms called enantiomers. Because soil microbes preferentially consume one enantiomer of each pair, the PCBs have characteristic chiral signatures when they volatilize from the soil in warm weather. PCBs emitted into air from other sources bear unaltered racemic chiral signatures that contain equal amounts of each enantiomer. Harrad’s study showed signatures in outdoor air matched the racemic
Texas, Louisiana, and Pennsylvania are home to the top 10 polluters among U.S. oil refineries in terms of cancer-causing emissions, according to a report released February 8 by the Environmental Integrity Project (EIP). The top nine emitters account for one-third of carcinogens released by the nation’s refineries, the report says, but only 15% of refining capacity. The environmental group’s analysis was based on emissions from 1999 to 2004 as cataloged by the U.S. EPA’s Toxics Release Inventory. EIP considered emissions listed as carcinogenic by the U.S. National Toxicology Program or the World Health Organization, including benzene, PAHs, and lead. Over the years studied, cancer-causing emissions decreased by 13% industry-wide but increased at several sites on the list.
APRIL 1, 2007 / Environmental Science & Technology n 2073
jupiterimages
Indoor air is a major source of PCBs
Environmentalt News signatures in indoor air, and not the altered soil signatures. Harrad’s use of these chiral signatures is an innovative way to distinguish between PCB sources, says Bidleman, who has done similar work on chiral signatures of chlorinated pesticides. The paper makes the strongest case for PCB–95, he says, adding that he would like to see more data col-
lected. “The policy implications are very, very large,” he stresses, a comment echoed by others. The findings could “lead to a reevaluation of remediation and cleanup priorities,” adds Martin Scheringer of the Swiss Federal Institute of Technology. Since 2000, researchers in Germany, Sweden, and Switzerland have documented that indoor air
can contain significantly higher levels of PCBs than the concentrations recorded inside Birmingham buildings, Harrad points out. “Before the ban of PCB in open systems in 1972, PCBs were used as plasticizers for joint sealants, [which can contain up] to 30% of PCB,” explains Martin Kohler, of Empa (Switzerland). —KELLYN BETTS
Another arsenic hot spot adding that “it’s not the case anywhere else that you have such clear boundaries of arsenic-safe and arsenic-polluted water.” Berg and his colleagues show that the elevated levels are con-
Skin lesions, such as the ones on this Cambodian man’s hands, are classic symptoms of chronic arsenic exposure.
fined to the floodplain between the Bassac and Mekong rivers in Kandal province and their adjacent riverbanks. Arsenic concentrations there averaged 233 µg/L, whereas concentrations to the east and west of the rivers were below 10 µg/L. While surveying samples for such parameters as water hardness, pH, and metal concentrations, the scientists also found another potential health threat: manganese. More than half of the samples taken from western areas, which were relatively arsenic
2074 n Environmental Science & Technology / APRIL 1, 2007
Micke y Sampson, Resource De velopment International , Cambodia
A brewing health crisis in Cambodia may be following the same pattern of arsenic poisoning that has devastated parts of Bangladesh and West Bengal (India). Poor surface- water quality recently led Cambodians to rely more heavily on shallow groundwater wells for drinking water, but recent reports indicate elevated levels of naturally occurring arsenic in some of these wells. In the first comprehensive groundwater survey of the area, published in this issue of ES&T (pp 2146–2152), scientists map out the magnitude of the contamination problem, which includes arsenic as well as manganese, in Cambodia. Those involved in the work are calling for immediate mitigation efforts. Michael Berg, an environmental chemist at the Swiss Federal Institute of Aquatic Science and Technology, and colleagues sampled 131 household wells across 3700 square kilometers (km2) of the Mekong River floodplain in Cambodia. Arsenic concentrations ranged from 1–1340 micrograms per liter (µg/L); 48% exceeded the 10 µg/L drinking-water guideline recommended by the World Health Organization (WHO). More than a third exceeded the 50 µg/L drinking-water limit set in many developing countries. “The big surprise is that the areas of arsenic contamination are sharply restricted, and we find perfectly safe water in some areas,” Berg says. “This is an extremely good message,” he notes,
free, contained manganese levels above the WHO guideline value of 0.4 milligrams per liter. Although arsenic’s human health effects are clear, only recently have studies indicated an association between manganese and neurotoxic effects in children, Berg notes. Only 18% of the wells sampled provided chemically safe drinking water. “This is a very important piece of work, because so far we haven’t been paying much attention to groundwater contamination” outside of the Bengal Delta, says Dipankar Chakraborti of Jadavpur University’s School of Environmental Studies (India). He maintains, however, that it’s too early to tell whether the situation is as severe as in Bangladesh, where the total arsenic-affected region is about 80,000 km 2 and some 43 million people have been drinking arsenic-laden water for several decades. As in Vietnam, Cambodians only began installing groundwater wells about 10 years ago. The symptoms of chronic arsenic exposure generally don’t appear until after 5–10 years of continuous exposure, and they become more pronounced over time. These findings are “part of an emerging picture of naturally occurring arsenic and manganese problems in shallow groundwater in many Asian countries,” agrees Alan Welch with the U.S. Geological Survey. The findings linking Cambodia’s topography with high and low arsenic concentrations offer a guideline for other surveys, he adds. —KRIS CHRISTEN
News Briefs
USDA , Photo by Keith Weller
The largest market basket survey of arsenic in U.S. rice, published in this issue of ES&T (pp 2178–2183), indicates that rice from California contains, on average, about 40% less arsenic than rice from the south central U.S.—Arkansas, Louisiana, Mississippi, Texas, and Missouri.
Rice from California contains, on average, about 40% less arsenic than rice from the south central U.S., researchers have found.
Andrew Meharg and co-workers at the University of Aberdeen (U.K.) measured arsenic levels in 134 samples of rice purchased from Arkansas and California supermarkets. Arsenic levels in south central U.S. rice averaged 0.27 micrograms per gram (μg/g), whereas arsenic in rice from California averaged 0.16 μg/g. The highest arsenic concentration was found in a sample of rice from Louisiana mills (0.66 μg/g), and the lowest was found in an organically grown rice from California (0.10 μg/g). The researchers inferred where the rice grew from the location of the processor named on the package label, and they confirmed it with multielemental fingerprinting combined with principal component analysis (PCA). By measuring levels of unusual elements, such as selenium, they could broadly determine the rice’s origins be-
cause “the plant reflects the environment it’s growing in,” explains Meharg. In a previous study (Environ. Sci. Technol. 2005, 39, 5531–5540), Meharg and colleagues measured arsenic levels and speciation in rice from various countries, including several samples purchased in Scotland and labeled as U.S. rice. Subsequent press coverage caused the USA Rice Federation to dispute the significance of the data (Environ. Sci. Technol. 2006, 40, 2077–2078). The team has now followed up on that initial study by analyzing more rice samples. Meharg speculates that the higher level of arsenic in rice from the south central U.S. can be traced to residual arsenic-containing pesticides still present in old cotton fields now used for growing rice. But not everyone is convinced. The higher amounts of arsenic in south central U.S. rice could be due solely to natural background levels in soils, notes Mark Barnett, an arsenic expert at Auburn University. Meharg mentions that rice growers are developing strains of rice especially for these high-arsenic soils, and he asserts in the paper that regardless of the original arsenic source, “the consequences for human health are identical.” Although U.S. rice consumption averages about 25 g per day per capita, some ethnic groups and people with gluten intolerance eat much more, Meharg says. On average, half the arsenic in rice is composed of the more dangerous inorganic form, although this varies widely, he continues. A person eating 100 g of rice that contains arsenic at a concentration of 0.3 μg/g would consume 30 μg of arsenic, probably half of which is inorganic. That person’s dietary exposure from rice alone would be higher than that from water, for which the U.S. EPA has set a maximum contaminant level of 10 μg of inorganic arsenic per liter.
Europe tightens CO2 standards
Transport is the only sector in Europe that has shown dramatic increases in CO2 emissions over the past 15 years. The European Commission (EC) has responded with two new proposals to tackle the problem. The first proposal will force carmakers to cut CO 2 emissions from new cars by 18% by 2012. Carmakers would be responsible for getting emissions down to 130 grams of CO 2 per kilometer (g/km) through technology improvements. Ultimately, the EC wants to bring emissions down to 120 g/km by 2012—25% below the 2005 level. It says the additional reduction is possible through increased use of biofuels, better tires, and measures to ensure drivers change gears at the right time. The second proposal, which updates a fuel-quality directive from 1998, outlines new fuel-quality standards that aim to achieve, by 2020, a 10% reduction in CO 2 emissions throughout the whole product life cycle. Overall, this should prevent emission of about 500 million metric tons of CO 2 . The proposal also contains two additional measures due to take effect in 2009: cuts by one-third in sulfur emissions and PAHs from diesel. The proposed standards would allow increased blending with biofuels, including up to 10% ethanol. Both measures await approval by member states and the European Parliament. Legislation based on these proposals is unlikely to be drafted until 2008. Meanwhile, California has already taken action on fuels. Transportation fuels sold in the state will have to contain 10% less carbon by 2020, under an executive order signed by Gov. Arnold Schwarzenegger in late January.
APRIL 1, 2007 / Environmental Science & Technology n 2075
jupiterimages
Arsenic in U.S. rice varies by region
Environmentalt News The levels of arsenic in rice from the south central U.S. make the report interesting, Barnett says, “however, I don’t think that we should overreact.” He points out that “none of the levels of arsenic in rice exceeded the 1.0 milligram per kilogram threshold recommended by some countries.” Barnett also notes that arsenic is a normal part of the human diet and that arsenic intake from food often
exceeds that from drinking water. Richard Loeppert, a soil chemist at Texas A&M University, says that the arsenic levels Meharg and colleagues report are about what he would expect. However, he stresses the limited usefulness of market basket surveys, indicating that they do not help to identify the soil, crop management, and varietal factors that might affect arsenic concentrations. Loeppert
also questions the value of PCA for sourcing rice, because soil metal concentrations can vary considerably over very short distances. Meharg hopes that U.S. researchers will be able to monitor and survey individual farms to “establish the relationships between the soil contamination and the rice contamination, which we have been doing elsewhere in the world.” —BARBARA BOOTH
Global methane cycles in flux
ASLAM KHALIL
factors that are difficult to quantify,” Khalil says. “All of them are reducing emissions” for the moment, Although the concentration of 25 parts per billion per year (ppb/ he adds. methane in the atmosphere nearyr) in 1980 to about 5 ppb/yr in Changes in these three facly doubled over the past centu2004. Their models also show that tors in China, in particular, could ry, fluxes of this greenhouse gas methane emissions “disturbancbe responsible for a major methseemingly leveled off during the es”—changes in fluxes—originated ane slowdown, Khalil says. Anpast 20 years. In a review pubat northern latitudes and rippled oxic conditions in flooded fields lished in this issue of ES&T make rice paddies perfect (pp 2131–2137), researchers, for producing methane. The led by Aslam Khalil of Portgas percolates up through land State University, modsoils or through plants el the sources and sinks of themselves, which act like methane. They also question drinking-straw conduits to whether human activities the atmosphere. Organic will have much of an impact fertilizer (such as hay or on future methane levels. manure) provides carMethane, which is 23 bon inputs that can times more powerful than stimulate methane CO2 as a greenhouse gas, production. is emitted from numerous Khalil’s team has sources, including wetlands, confirmed previous cows, and thawing arctic perresearch showing mafrost. But the gas is also that flooded fields reRice fields in China contribute a significant amount of consumed by microbes and lease six times more methstored geologically, making its methane, a greenhouse gas, to the atmosphere. ane than intermittently cycles hard to pinpoint, despite flooded fields. Straw apseveral decades of research. Recent out to affect the rest of the globe. plied as fertilizer leads to twice as reports have documented tropiThey hypothesize that possible much methane from intermittentcal upland sources and reassessed fluctuations in hydroxyl radicals, ly flooded fields than from bare, emissions from arctic lakes, adding which destroy methane, could drained fields, according to initial to previously known natural emishave modulated the gas’s concendata presented by Khalil at the sions. “People keep finding sources, trations during the past 20 years. American Geophysical Union anbut nobody’s finding the sinks,” Khalil and co-workers also posnual meeting last December. says Patrick Crill, a biogeochemist tulate that the agricultural compoAnecdotal evidence shows that at Stockholm University. “Undernent of methane—which accounts Chinese farmers now let their standing the root causes of the balfor about 20% of the global budget fields dry out and that they are no ance will be important, especially if of approximately 500 teragrams a longer applying as much organic CH4 begins to increase again.” year—will not change much in the fertilizer, Khalil notes. As-yet-unIn their new assessment, Khalil near future. Organic fertilizer inpublished surveys, he says, show and co-workers model recent atputs, the amount of land flooded that farmers are also using modimospheric methane trends, and for growing rice, and political and fied rice plants that require less find a drop in methane fluxes from sociological changes “are the three time to grow. Once farmers meet 2076 n Environmental Science & Technology / APRIL 1, 2007
predict, says Hugo Denier van der Gon, of TNO Built Environment and Geosciences (The Netherlands). One confounding factor will be the growing demand for rice, he comments. —NAOMI LUBICK
Risk assessment rebuff for OMB The White House Office of Management and Budget’s (OMB’s) attempt to standardize risk assessments conducted by federal agencies has been unanimously rejected as “fundamentally flawed” by a National Research Council (NRC) committee. As a result, OMB will rethink its approach to developing improved guidance for risk assessment, according to Steven Aitken, acting administrator for the Office of Information and Regulatory Affairs (OIRA), an agency within OMB. It has yet to be determined whether OMB will revise its draft risk assessment bulletin, issue a new draft, or devise another alternative, he says. OIRA, which oversees all of the government’s rulemaking, released its draft bulletin in January 2006 as former administrator John Graham’s 5-year reign at OIRA was coming to a close. The groundbreaking risk document followed OMB guidelines for agencies on peer review, data quality, and cost–benefit analysis. In the most recent risk-assessment bulletin, OIRA attempted to establish technical standards for all agencies on issues such as uncertainty analysis, determination of adverse effects, and what emphasis risk assessments should place on sensitive populations that are likely to be more vulnerable to a risk, such as environmental pollution. But OIRA overstepped its authority, according to the NRC report Scientific Review of the Proposed Risk Assessment Bulletin, released in January. The committee strongly recommends that risk assessments be developed by agen-
cies themselves because different agencies have different needs. Harvard Center for Risk Assessment director James Hammitt, a former colleague of Graham’s, says he’s surprised that the committee was so critical. “Much of the bulletin reflects what I take to be common wisdom in the field,” says Hammitt. Perhaps the issue is not so much how to conduct risk analyses, Hammitt says, as how much influence the White House should have. The NRC panel seems to be arguing for more White House deference to agency and departmental expertise, he notes. But committee member and risk-assessment expert Joseph Rodricks noted that, for uncertainty analysis, the draft bulletin set standards that exceed the current state of the science. The NRC committee recommends that OIRA establish a baseline for the quality of each agency’s risk assessments before offering general guidance. For example, the U.S. EPA is routinely praised for its use of advanced risk assessment methods, but many other agencies are not as far along. The rebuff of the bulletin may mark the end of Graham’s more “hands-on approach” to OMB directives, says former OMB analyst Richard Belzer. OMB has traditionally set targets and then let each agency figure out how to meet them, he says. Belzer predicts that OIRA will return to this less prescriptive approach by emphasizing cost–benefit analysis over detailed guidelines. —REBECCA RENNER
News Briefs Toxic substances affect brain similarly
Toxic substances with different chemical properties act through the same regulatory pathway to disrupt cell function, researchers report in a PLoS Biology paper (2007, 5, e35). Researchers at the University of Rochester Medical Center tested methyl mercury, lead, and the herbicide paraquat on neural progenitor cells—advanced-stage stem cells that have begun to specialize into specific brain cells. They found that environmentally relevant levels of methyl mercury and lead as well as low levels of paraquat made the cells 20% more oxidized. This activated a chain of reactions that eventually stopped cell division. They saw the same effects of methyl mercury on mice tested from conception to 21 days after birth. Understanding these pathways could aid in largescale toxicological screening, the authors write.
Report: renewables are doable
Renewable energy could reduce U.S. contributions to global warming substantially by 2030, according to a team of academic, government, and private researchers working with the Sierra Club and the American Solar Energy Society (ASES). Researchers from Oak Ridge National Laboratory and elsewhere calculated that overall, energy efficiency measures for buildings and other sites could cut as much as 688 metric tons (t) of carbon by 2030. And renewable energy— such as concentrated photovoltaics and geothermal—could reduce carbon by an additional 523 t. That could help the U.S. cut 60–80% of its carbon emissions, according to Tackling Climate Change in the U.S. Released on January 30, the report contains nine papers from ASES’s meeting last summer.
APRIL 1, 2007 / Environmental Science & Technology n 2077
NIH
their government quotas, they may choose not to recultivate that acreage with rice that year, further cutting down on the time that land is flooded and producing methane. But future changes in human land use remain challenging to
