Environmental t News Snow shows perfluorochemical source
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ucts such as stain-repellent coat ings that escape from factories or consumer products into the atmo sphere, where they are transported and oxidized to form perfluorooc tanoic acid (PFOA) and other per fluorocarboxylic acids. The competing, oceanic hy pothesis, articulated most fully by Cousins and colleagues, is that his torical emissions, rela tively uncontrolled in the past, have their final rest ing place in the ocean, where currents transport them toward the poles. In the Arctic, these lega cy pollutants are incor porated into the marine food web. They can also concentrate in the ocean surface layer, from which they can be taken up by marine aerosols and land on the ice. Solving the mystery has important ramifica tions, says toxicologist Kurunthachalam Kannan of the New York State Department of Health’s Wadsworth Center. “If we can identify the major sources, effective regulatory decisions can be made to reduce future emis sions,” he says. Canadian officials, concerned about the country’s Arctic regions, have taken an aggressive regula tory stance against new fluorotel omer products. The action is based on the atmospheric theory pro moted by Mabury, according to John Arseneau, director general of Environment Canada’s risk-assess ment directorate. One way to search for a marine aerosol source is to use sodium as a tracer. Because perfluorinat ed chemicals are powerful surfac tants likely to concentrate in the Cor a Young
3M
Corp.’s voluntary several different perfluorochemi phaseout of prod cals. These levels are 2–3 orders of ucts based on per magnitude below those measured fluorooctane sulfonate (PFOS) at lower latitudes. chemistry has led to a rapid de “The drop in PFOS is dramat cline in PFOS levels in Arctic snow, ic—about 500% from the high in according to new research pub 1998 to the recent lower levels,” lished in this issue of ES&T (pp says Young. But Stockholm Univer 3455–3461). The general trend for sity chemist Ian Cousins has res PFOS in the ice cap is consistent ervations. “I’m concerned about with previously re ported declines in PFOS levels in ringed seals (Environ. Sci. Technol. 2007, 41, 42–49). The new re search could help put an end to the controversy within the scientific com munity over the ex act source of PFOS in the Arctic. Such a quick en vironmental response to the phaseout, which 3M an nounced in 2000, Snow-pit samples show a dramatic drop in PFOS levels. combined with new data on the relative concentraderiving time trends from the tions of other perfluorochemicals snow layers, because of the mobil in Arctic snow and ice, supports ity of perfluorinated compounds, an atmospheric source, say the especially during melting of ice authors. The Arctic has no direct and snow in the spring and sum sources for nonvolatile perfluoro mer,” he says. “Ice melting could chemicals, so their presence there cause some chemical migration has long been an environmental to lower depths, but not much,” mystery. Young says, noting that other iceUniversity of Toronto chemist cap studies have reached similar Cora Young and colleagues collect conclusions. ed ice samples from the high Arc Two different theories have tic in the spring of 2005 and 2006 been proposed to explain the pres and a series of samples from a 6.8ence of nonvolatile perfluorochem meter-deep pit on Devon Island in icals in the Arctic. According to the Canadian province of Nuna the atmospheric theory, advanced vut. A pit this deep dates back to by University of Toronto chemist 1996, the authors say. Young took Scott Mabury and colleagues, the large-volume samples and concen most significant source is fluoro trated them 100-fold to find pico telomer alcohols. These are volatile gram-per-liter concentrations of precursors of commercial prod
© 2007 American Chemical Society
richment factors for perfluorinat ed compounds are unknown. The extreme enrichments reported by Young most likely rule out marine aerosols as a source, argues ma rine chemist Robert Duce at Texas A&M University. In addition, “the complete lack of correlation with sodium also supports the conten tion that this material on the ice cap is not ocean-related,” he says. —REBECCA RENNER
New Jersey dives into PFOA water guidance New Jersey officials have issued the most stringent preliminary health-based guidance yet on per fluorooctanoic acid (PFOA) levels in drinking water in the U.S. The guidance, a first step in regulating PFOA, was issued as a benchmark so that water companies can judge whether the low levels of perfluori nated chemicals in their drinking water are safe for humans. New Jersey is the latest state to issue advice on PFOA in drink ing water; the guidance follows action in two other states where past chemical industry operations have led to PFOA contamination of drinking water. PFOA is unregulated in the U.S. Last year, the U.S. EPA’s Science Advisory Board (SAB) classified PFOA as a likely human carcino gen, but EPA’s risk assessment pro cess, a precursor to any regulatory action, is likely to take years to complete, according to the agency. “States are running with this be cause the EPA process is too slow,” says Kristan Markey with Environ mental Working Group, an advoca cy organization. “This is the latest in what will be an ongoing process of research and regulation of this ubiqui tous toxin,” says Boston Universi ty environmental health scientist
Richard Clapp, who praised New Jersey’s recommendation. Early in dications are that, in addition to cancer, PFOA may be associated with birth defects and abnormal blood lipids, he notes. However, the low levels that are ubiquitous in the U.S. population have not been clearly linked to any adverse effects. PFOA, also known as C8, is a processing aid used in manufac turing fluoropolymers that have a wide variety of applications, in cluding nonstick cookware. The chemical can also be a byproduct of manufacturing fluorotelomers, which are used on grease-resistant food wraps and stain-resistant tex tiles. Granular activated carbon can remove perfluorochemicals from drinking water. The New Jersey Department of Environmental Protection (NJDEP) made its recommendation of 0.04 parts per billion (ppb) at the re quest of the Pennsgrove Water Supply Company, according to the state’s guidance document. PFOA and other perfluorocarboxylates have been detected with elevated levels in the system’s drinking wa ter near DuPont’s massive Cham bers Works chemical plant. The water pollution surfacing today in West Virginia is thought
News Briefs Montreal beats Kyoto on climate controls
The 1987 Montreal Protocol has protected the ozone layer by controlling emissions of chlorofluorocarbons (CFCs) and other related chemicals on a global scale. Now, researchers say it also seems to have slowed down climate change. By cutting back on ozone-depleting substances, the treaty prevented some global warming because CFCs are also potent greenhouse gases. According to the team’s calculations, published in Proceedings of the National Academy of Sciences U.S.A. (2007, doi 10.1073/pnas.0610328104), the treaty had more impact on climate change than the first phase of targets set by the Kyoto Protocol, which limits CO 2 and other greenhouse gases.
Bigger fish to fry?
Size is not all in the genes. An organ ism’s features are decided by interactions between its genes and its environment. Take the transgenic coho salmon, for example. A new study published in Proceedings of the National Academy of Sciences U.S.A. (2007, 10.1073/pnas. 0608767104) shows that when these fish—genetically modified to make extra growth hormone—are raised in hatcheries, they can grow 25 times heavier than their wild cousins and become more predatory. But when reared in a streamlike setting, the transgenic fish are only twice as heavy as wild salmon and prey on fewer fish. The authors caution against releasing transgenic organisms into nature without a better understanding of how transgenes manifest in different environments.
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ocean surface layer, their abun dance might be enriched relative to that of sodium. Young finds that on the ice cap, the ratio of PFOA to sodium is enriched 10,000 times relative to oceanic ratios. In addi tion, no correlation exists between levels of sodium and the perfluo rochemicals, so she discounts ma rine aerosols. Such dismissal is premature, says Cousins, who notes that en
Environmentalt News to come mainly from legacy opera tions. DuPont and other compa nies that use or make PFOA have agreed with EPA to voluntarily re duce its use. A November 2006 consent agreement between offi cials with DuPont and EPA slashed the drinking-water action level for PFOA from 150 to 0.50 ppb in West Virginia. Under the agree ment, DuPont has offered bottled water or water treatment for pub lic or private water users living near its Washington Works plant if the PFOA level exceeds the ac tion level. In March, Minnesota officials
halved their state’s recommend ed safe level for PFOA in drink ing water from 1 to 0.5 ppb. PFOA and other perfluorochemicals have turned up in public and private drinking-water wells in communi ties east of St. Paul. According to 3M officials, the sources are land filled industrial wastes from a 3M manufacturing plant. The com pany has already voluntarily paid several million dollars to install carbon treatment at the local water utility and to connect affected pri vate wells to the water system. NJDEP risk assessors used the SAB scientific review as the start
Pricing tomorrow’s coal-fired power plant capture and storage (CCS) capabil ity before or after the plant is built? The researchers used the In tegrated Environmental Control Model, a well-known, publicly available tool developed at CMU and designed to compare the per formance, emissions, and cost of U.S. DOE / NE TL
The price tag for a new coal-fired power plant runs into the billions of dollars. With energy demand rising at 1% per year in the U.S. and carbon-control legislation be ing discussed enthusiastically in Congress, some utility executives are in gridlock over which tech nology to choose for future power needs. New research published in this issue of ES&T (pp 3431–3436) shows utility executives and poli cy makers that coal, and lots of it, can continue to be burned without consumer costs rising much high er than they are today, provided that several policy actions are tak en soon. Coauthors Joule Bergerson, a postdoctoral fellow at the Univer sity of Calgary (Canada), and Les ter Lave, codirector of Carnegie Mellon University’s (CMU’s) Elec tricity Industry Center, provide an engineering–economic analy sis for utility executives and pub lic officials. The paper aims to help decision makers choose a coal technology, given their be liefs about future environmental regulations. Should the plant use traditional, pulverized coal (PC) technology or the slightly more ef ficient integrated coal gasification combined-cycle (IGCC) process? Should it be equipped for carbon
One option for future power generation is the integrated gasification combinedcycle (IGCC) system, shown at Tampa Electric’s Polk Power Station (above).
various electricity generation tech nologies. Using 2002 dollars ad justed for inflation, they inserted recent costs of actual mediumsized power plants and engineer ing cost estimates of new plants with similar power outputs of 450–480 megawatts. The plants all burned the same high-Btu-value coals. The results are surprising. “Peo ple think IGCC would make more
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ing point for determining a prelim inary guidance level for lifetime exposure, according to NJDEP tox icologist Gloria Post. One of the studies examined by the SAB, a 2year rat study, found health effects at even the lowest blood PFOA levels. Officials in New Jersey and Minnesota note that they will re evaluate their findings as addition al data emerge. This year, the first results will be seen from the C8 Health Project, an assessment of PFOA risks based on blood samples collected from 64,000 people. —REBECCA RENNER
sense to build for future genera tion, but our numbers didn’t show that,” Bergerson says. “We couldn’t find a case for a utility to build an IGCC plant unless Congress im posed a very high carbon tax and the tax was implemented very soon,” she adds. The analysis reveals that a tax could tip the scale: if a company is committed to building a PC sys tem, “the carbon price would have to be $46 per ton of CO2 or more to justify adding CCS,” the authors write. A lower tax or one that was delayed would have no effect, they add, because a cost analysis would steer the generator to build the cheap PC plant and pay the tax. Still, they caution that these esti mates are subject to a myriad of uncertainties. The paper makes a unique con tribution by examining the dif ference between what the public prefers and what company execu tives want from a new power plant and placing a dollar amount on these differences. “This appears to be the first time I’ve seen a real cost assigned to public and private motivations,” says Rita Bajura, for mer director of the U.S. Depart ment of Energy’s National Energy Technology Laboratory. “They look at private and public motivations, and they do so without bias. They come at it with a purely academ ic viewpoint,” which, she says, is
ing in the next few years. BGE, the utility that serves customers in central Maryland, recently re ceived approval for a 72% price in crease, Lave says, partly because energy prices were frozen when the state deregulated the electric ity industry. As deregulation poli cies are removed from other states, prices will rise there as well. “In the future, the additional cost of carbon capture and storage will be noticeable but won’t be extraordi nary,” Lave says. —CATHERINE M. COONEY
Bush expands influence over regulations The Bush Administration’s cam paign for regulatory reform has now taken aim at guidance docu ments, a potpourri of messages from federal agencies that tell busi nesses and citizens how to imple ment regulations. A new directive from President Bush orders agen cies to submit significant guid ance documents for review by the White House Office of Management and Budget (OMB). It’s uncertain how broadly OMB will interpret its new authority. Yet the directive set off a firestorm of alarm among environmental and public-health advocates, who say that an aggres sive White House could impede or change agency guidance. Executive Order 13422, is sued by President Bush on Janu ary 18, 2007, is accompanied by OMB’s Final Bulletin for Agency Good Guidance Practices. These two documents boost White House control over a wide range of regu latory activities. During the Bush Administra tion, OMB has often operated un der the public radar by issuing documents that attack environ mental science; it appears to be the White House’s favorite approach toward weakening environmental and public-health regulations, says David Michaels, an epidemiologist at George Washington University. “This was clearly written to target
risk assessments by the EPA,” Mi chaels says. The new order fits this pattern that includes a draft bulletin pro posing overhauls to agency risk as sessments, issued in 2006, and the 2003 guidelines for agencies on how peer review of regulatory science should be conducted, critics say. Beginning in July, federal agen cies will have to prove the need for new regulations on the basis of specific failures of the free market, such as lack of competition pre venting the provision of safe alter natives to toxic substances. Each agency head must designate a po litical appointee within the agency to control the writing of new rules. Environmental advocates say they are concerned that the new order will significantly slow down EPA’s work. “The bulletin could be used to interfere with chemical as sessments for EPA’s Integrated Risk Information System (IRIS) and the National Toxicology Program’s Report on Carcinogens,” says Jenni fer Sass, a senior scientist with the Natural Resources Defense Coun cil, an advocacy group. OMB has already taken from the IRIS staff at EPA the assessments for formalde hyde, ethylene oxide, and trichlo roethylene, Sass says. “We’re very concerned that this new OMB initiative may pre vent that information from com
News Briefs Asian pollution strengthens storms
Air pollution from Asia isn’t only a problem in Asia. A new study shows that human-made pollution from Asia—mainly soot and sulfate aerosols—is intensifying winter storm activity over the Pacific Ocean. Renyi Zhang and colleagues used satellites to track pollution and clouds between 1984 and 2005. Aerosol particles increased during that time because of coal burning in China and India. The researchers say this increase enhanced the cloud updraft to generate stronger thunderstorms. More intense Pacific storms can ultimately affect global circulation, and increased transfer of heat and particles to the poles could exacerbate warming there. The study was published in Proceedings of the National Academy of Sciences U.S.A. (2007, 104, 5295–5299).
New aerosol source
Atmospheric chemistry models are notorious for underestimating organic aerosol levels in the air. Now, researchers at Carnegie Mellon University believe they have discovered the missing source: photooxidation of hydrocarbon emissions. Allen Robinson and colleagues exposed diesel exhaust to UV light and tracked the primary organic aerosols (POAs), particles once thought to be stable and nonvolatile. A significant fraction of the POAs evaporated and were then oxidized by UV light to form secondary organic aerosols (SOAs). The findings, published in Science (2007, 315, 1259–1262), show that a large fraction of hydrocarbons spewing from cars and trucks are oxidized to SOAs by the sun, instead of condensing into POAs. Those highly oxidized and hydrophilic SOAs play a role in regulating climate and may cause adverse health effects.
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hard to find. “Almost any interest ed player has a vested interest in this,” Bajura says. Karen Palmer of the nonprofit research group Re sources for the Future agrees that an objective discussion of public versus private interests has been overlooked and suggests that this area of research be expanded. Lave says the paper shows that the cost of generating electricity with CCS will rise sharply but that the cost of delivered power to con sumers won’t be much more than what some customers will be pay
Environmentalt News ing out, or coming out as the most robust scientific assessment by the agency experts,” Sass says. IRIS, a database that documents human health effects, is a tool used world wide to assess a chemical’s toxicity. The Bush Administration has not explained why the executive order was needed, a point under scored by a report by the Congres sional Research Service presented at one of two House of Represen tatives hearings in February. That left business leaders, including William Kovacs, vice president of the U.S. Chamber of Commerce, to offer their interpretations of the president’s order. The move was justified, because some guidance documents have
had the power and economic im pact of rules yet have escaped the public scrutiny required for rule making, Kovacs said when testify ing before Congress. Alarms raised over the executive order are “much ado about nothing,” says Dan Troy, chair of the American Bar Associa tion (ABA) Section of Administra tive Law and Regulatory Practice. The two documents will increase accountability and transparency and are just what the ABA recom mended, he says. Guidance documents are not legally binding and can include internal memos, letters to the reg ulated community, and speech es. They are written by agency staff members, who are often well
versed in the requirements of laws concerning the environment and public health. But the new order and directive could be interpret ed to apply to any document that is not a rule but that is used in regulatory policy and that is nor mally developed at the agency lev el by scientists. This would result in documents being written in stead by economists and lawyers at OMB, critics point out. Congress has not signaled how it intends to address its concerns over the action, but a new admin istration could easily revoke the order, says Stuart Shapiro, a former analyst at OMB’s Office of Infor mation and Regulatory Affairs. —JANET PELLEY
Sharing sustainable solutions
R amaswami et al .
especially in the face of water scar city (Environ. Sci. Technol. 2005, 39, 476A–477A). Increasing awareness about the ver, and Health Sciences Center. Other successful technologies planet’s changing climate and di These “very sustainable” solutions cited in the paper are water-medi minishing resources has made sus can be successfully adopted in de ated thermal heating and cooling, tainability a key issue around the veloped countries after further and using biogas for waste man world. In two new papers published analysis and improvement, says agement and energy supply. in this issue of ES&T (pp 3415–3421; Ramaswami. Effective distribution and im 3422–3430), James Mi plementation of technol helcic of Michigan Tech ogy go hand in hand with nological University and economics and gover colleagues present an ar nance tools. In the sec ray of ideas and tools from ond paper, the authors developing countries that discuss such successful have proven useful in im instruments. plementing sustainable Community lending living. Using specific case programs, such as those studies, the authors argue sponsored by Grameen that indigenous knowl Bank, earned world edge needs to be included wide recognition when in global conversations on the bank shared the 2006 Nested water temples in Bali are a well-documented case of sustainability. Nobel Peace Prize with communal sharing of resources. “Developing nations Muhammad Yunus for typically have a long history of In the first paper, Mihelcic, Ra success in economic and social de practical innovation and suc maswami, and Julie Zimmerman velopment in Bangladesh. But less cessful application of indigenous of Yale University document sci well-known are the centuries-old knowledge systems,” write the au entific and technological tools in communal sharing practices that thors. And yet, the flow of infor developing countries. One such help communities survive despite mation between the two disparate example is rainwater harvesting. inadequate resources. For exam parts of the world is almost always The UN Environment Programme ple, the Indonesian island Bali has unidirectional. “There is a lot of supports rainwater harvesting— a limited freshwater supply, which knowledge transfer from the de practiced for centuries on various flows to the fields through natural veloped to the developing world,” small islands and communities all and constructed irrigation chan says author Anu Ramaswami of over the world—as one of the best nels and is controlled by small wa the University of Colorado, Den alternatives to freshwater supply, ter temples at individual farms 3398 n Environmental Science & Technology / MAY 15, 2007
transfer knowledge from all these other fields to sustainability,” says Marian Chertow, an industrial en vironmental management expert at the Yale School of Forestry and Environmental Studies. Although the ideas themselves “aren’t en tirely novel”, they are a “well-cho sen” group of ideas and examples. Adopting these tools in other plac es will involve many factors, in cluding “the scale to which the solution is appropriate, patterns of development, and the capital base of that particular place,” she adds. Environmental engineer Do menico Grasso of the University of Vermont agrees. “A lot of our work in the U.S. is involved in high-tech environmental engineering that is intellectually stimulating but is not directly exportable,” he says. These papers are “a great way for Ameri cans to open their eyes to some ex citing technologies and economic instruments and societal instru ments that are available overseas.” —RHITU CHATTERJEE
A potential new Crypto source
Snapping fluorocarbon superbonds
A new study describes a computerdesigned molecule that can degrade fluorocarbons, the chemicals responsible for depleting the ozone layer. The carbon–fluorine bond is the strongest one between carbon and another element. This makes fluorocarbons popular as refrigerants, pesticides, and nonstick materials, but it also makes them hard to destroy. Carlos Gonzalez of the National Institute of Standards and Technology and colleagues studied naturally occurring bacterial enzymes that are known to rip apart carbon–fluorine bonds. The team designed a molecule that acts similarly to the enzymes, which are hard to exploit for large-scale uses. They hope this magic molecule, described in the Journal of Physical Chemistry A (2007, 111, 268–272), will one day reduce fluorocarbon levels.
Stopping and surviving climate change
C. parvum (labeled here with a fluorescent antibody) is one of the two species known to infect humans.
and herd animals,” says Jellison. “And agricultural runoff was con sidered to be a very big contributor to surface-water contamination.” To determine whether there were additional sources of Cryptosporidium in these waters, Jel lison sampled two brooks—Brook SF and Brook JF—that were down stream from agricultural sites and suspected of agricultural contami nation. Both of the brooks drain into the Wachusett Reservoir, the primary source of drinking water
Eric M. Gage, Jellison L ab
It is not the deadliest of water borne pathogens, but Cryptosporidium spp. can infect thousands and kill scores by causing diar rhea. Since the 1993 outbreak in Milwaukee, Wis., which infected 400,000 people and killed 104, re searchers and water-quality regu lators have tried to keep a strict eye on the deadly protozoa in drinking water. Now, research published in this issue of ES&T (pp 3620–3625) reveals six novel genetic variants and a new potential source of Cryptosporidium—migratory birds. When study leader Kristen Jel lison, now an assistant professor at Lehigh University, began her re search as a graduate student at the Massachusetts Institute of Tech nology (MIT) in 1997, she want ed to identify the main source of Cryptosporidium in drinking-water supplies in the Boston area. “Cryptosporidium was found in cattle
News Briefs
The consequences of global warming are dire, but acting now will allow humans to both adapt to changes and prevent the worst from happening. So says a group of scientists convened by the academic membership society Sigma Xi and sponsored by the UN to produce their report, Confronting Climate Change: Avoiding the Unmanageable and Managing the Unavoidable. The group concluded that policies should aim to limit global warming to 2.5 °C or less above the preindustrial temperatures of 1750. This requires immediately reducing methane and soot emissions, as well as limiting CO 2 levels to 450–500 parts per million—all possible using current technologies, the panel says. Released in February, the full report appears in the May–June issue of Sigma Xi’s magazine, American Scientist.
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through local water associations called “subak”. A communal sharing of wa ter requires that farmers stagger their crops such that both up stream and downstream farms re ceive enough water and the closely clustered farms receive water at the same time. This also improves pest management, because nearby farms that have the same “farming and fallow periods deprive pests of their natural habitat,” write the au thors. To plan a water-usage sched ule, regular meetings are held at individual-farm, subak, and in tersubak levels. This system was officially encouraged by the Bali government after massive failure of water-sharing and pest-man agement decisions targeted at the individual level in the 1970s and 1980s. Similar successful communal sharing strategies are also found among Mongolian herders and other groups in Asia and Africa. “What the authors have done is
Environmentalt News for Boston and surrounding areas. The team monitored the two brooks every month from June 2001 to May 2002 for the presence of Cryptosporidium oocysts (the hard-walled infective stage). To isolate the oocysts from the wa ter, they used a standard immuno magnetic separation method. They then amplified the DNA from the oocysts to identify the pathogens. Although Brook SF appeared to be free of the pathogen, Brook JF showed six new genetic variants or genotypes of Cryptosporidium. The oocysts were found only from June to November, when migratory birds such as Canada geese (Branta canadensis) are known to stop in the region. The authors also analyzed oo cysts from a Canada goose in New York and one in Illinois. Compari son of the sequences revealed that one genotype from Brook JF was identical to the one in the New York goose, and yet another was
very similar. A third genotype was closely related to oocysts in the Il linois goose, whereas the remain ing four seemed unrelated to other known genotypes of Cryptosporidium. The observed genotypes were not related to any found in cattle. Taken together, the results suggest that in this agricultural watershed, “birds were more of a source than herd animals,” concludes Jellison. Of all the known species and genetic variants of Cryptosporidium, only two—C. parvum and C. hominis—are known to cause cryptosporidiosis in humans. “There’s now growing recognition that some populations, probably mostly immunocompromised in dividuals and malnourished chil dren in particular, are susceptible for infection with some of the spe cies that we hadn’t previously con sidered to be causes of human infections,” says coauthor David Schauer of MIT. Despite the fact that the results generate no imme
diate public-health concern, the genetic variants described in this study might one day be found to be pathogenic to humans, especially in susceptible populations, he says. So, there is a need to “build up a good picture of, or good database of, what the patterns of human in fections are with these genotypes as well,” adds Schauer. Microbiologist Joan Rose of Michigan State University agrees. Cryptosporidium, she says, repro duces both sexually and asexu ally, which makes “the emergence of more pathogenic or virulent forms” very easy. Knowing the ge netic diversity and distribution of the pathogen helps in understand ing the evolution of virulent forms from nonvirulent ones. The results are especially important in the wake of the recent concern over avian flu, because “we know there is a role for birds in moving things around,” she adds. —RHITU CHATTERJEE
As more and more farmers spread solid waste from sewage treatment plants onto their fields, people liv ing in rural areas have begun re porting sicknesses that could be related to the dispersal of these bio solids. But making that connection remains as difficult as measur ing the airborne particles coming from the sludge. A new framework published in this issue of ES&T (pp 3537–3544) could eliminate the need for complex aerosol measure ments, making it easier to predict the health impacts of applying bio solids on agricultural lands. Jordan Peccia of Yale University and his colleagues at Arizona State University monitored class B bio solids—less refined than the more processed class A form, which con tains no pathogens—from waste water treatment plants in Phoenix, Ariz., as they were being flung onto a field with a standard side-slinging applicator. They tracked airborne
Jordan Peccia
Aerosolized contaminants from biosolids
A side-slinging biosolids applicator flings sludge toward four PM10 monitors.
particulate matter less than 10 mi crometers in diameter (PM10) with stationary monitors under various conditions and measured aerosol concentrations of U.S. EPA regulat ed metals, three biosolids indicator bacteria, and endotoxin. The team assessed the content of the bulk biosolids before applica tion and compared the results with the measured metals, pathogens, and other components of interest in their captured aerosol samples. The results showed a direct correla
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tion between the concentrations of pathogens and other contaminants in aerosols and those measured in the bulk biosolids. “This measurement framework allows for the estimation of patho gen and toxin concentrations in aerosols, without the need for aero sols measurement,” says Peccia. Aerosol recovery techniques are destructive and notoriously diffi cult to carry out, particularly for pathogens. “These difficulties are directly responsible for the pau city of pathogen information that we have on the topic of biosolids bioaerosols,” adds Peccia. Aerosol recovery rates reported in the liter ature are currently about 10%. The new research used a “good experimental design and a novel way to figure out the distribution of the [metals and other contam inants] over the area,” says the U.S. Geological Survey’s Ed Fur long, who coauthored recent work looking at biosolids as a source of emerging contaminants (Environ. Sci. Technol. 2006, 40, 7207–7215).
“They’ve quantified what’s moving off-site from the most common bio solids application technique using biosolids from a single wastewater treatment process,” Furlong says. “These new data will be very useful for modeling exposure of individuals residing next to agri cultural land where biosolids are applied,” says Rolf Halden of Johns Hopkins University. “This study is of great importance, since billions of dry pounds of biosolids are landapplied each year.” Since the 1970s, recycling of biosolids in different forms—from almost liquid to muddy sludge— has been promoted by EPA and wastewater treatment plants. In 2003, EPA asked the National Acad
emies to weigh in on its limits for metals and other contaminants in biosolids applied to agricultural lands. The panel found no docu mented public-health effects and encouraged subsequent research to fill data gaps on health effects as well as on risk assessment. Tracking by states and other agencies was “shockingly lacking”, says Ellen Harrison, who is the di rector of the Cornell Waste Man agement Institute, and served on the National Academies panel. She says she “became convinced by all the reports that [illness] is scientif ically plausible” but that the moni toring and methods to make the connection are lacking. The new research, Harrison says,
is interesting but possibly limited. “Sludge is not sludge is not sludge,” she comments, implying that not all sludge is the same. She suggests that the current ES&T paper applies only to particular class B biosol ids in certain application settings. “I think it’s a good step, but I would be loath to plug into a risk assess ment numbers from one sludge.” Peccia and colleagues suggest instead that the correlations be tween bulk biosolids and aerosol emissions “provide a more funda mental, bulk-biosolids-based ap proach” that can be applied “to different land application scenarios and a broader range of toxins and pathogens.” —NAOMI LUBICK
A heavy-metal history in Peru
Colin Cooke
reported the findings in Science (2003, 301, 1893–1895). Now that the team has found A dirty little secret lies buried at Archaeologists have known for evidence of early metal use in Bo the bottom of a lake in Peru. Ac some time that the Incas used sil livia and Peru, they plan a larg cording to new research published ver extensively, but no one had er survey to learn more about in this issue of ES&T (pp 3469– found evidence of local smelting. how the technology was spread 3474), the lake sediments contain That may be because archaeolo throughout the New World. evidence that pre-Incan cultures in gists usually rely on finding arti “These lakes are natural ar the Morococha region of the Andes facts, Cooke says. The team looked chives, a book no one has thought were smelting copper and its alloys to sediments, knowing that any to open,” says Earl Brooks, ad from ore as early as A.D. junct professor of geology 1000, leaving behind traces at George Mason Universi of metal pollution. The An ty. Brooks has been study dean people later switched ing lead at a mining site in to silver when Incas moved Bolivia and says that geo into the area around A.D. logical techniques could 1450. also help reveal historic use The authors say villag of other metals of current ers probably ramped up concern, such as mercury silver production to pay the and arsenic. heavy tribute taxes that In The findings “raise cas demanded in the form some potentially serious of silver objects. About 80 questions about effects on years later, Spaniards came these humans at the time,” Researchers uncover a timeline for human use of metals. with more advanced tech says the University of Flor nologies. “Once the Span ida’s Mark Brenner, who ish show up, atmospheric pollution metal artifacts in Peru “may have uses sediment cores to study en goes up 10-fold,” says Colin Cooke, been looted or melted down and vironmental change. The high An the first author on the paper, who sent to Spain” long ago. Two coau des have a good environment for worked on the project as a gradu thors of the ES&T paper, Mark Ab preserving biological specimens, ate student at the University of bott of the University of Pittsburgh he says, adding that “it might be Pittsburgh. Airborne metal pollu and Alexander Wolfe of the Uni worth looking at metal levels in tion rains down on small lakes, ul versity of Alberta (Canada), first human remains” to see how much timately leaving behind traces in found evidence of pre-Incan silver people were exposed to. the bottom sediments. smelting in the Bolivian Andes and —ERIKA ENGELHAUPT MAY 15, 2007 / Environmental Science & Technology n 3401
