Environmental▼News PFOA half-life of 4.37 years, indicating the potential for bioaccumulation in humans, according to the preliminary risk assessment. EPA doesn’t know how people are being exposed to PFOA, according to Johnson. It may be released during manufacturing or processing, and it may also be formed due to the breakdown of other fluorinated compounds made by the telomerization process. Scientists who are studying the problem hypothesize that PFOA, which is nonvolatile, is a breakdown product of more volatile precursors, including telomers, according to environmental chemist Scott Mabury of the University of Toronto. EPA’s draft report assesses current scientific work, including studies by various perfluorinated chemical manufacturers. The document reviews human occupational studies and animal toxicological studies, focusing on adverse developmental effects observed in a two-generation rat study completed in March 2002 by contract lab Argus Research in Horsham, Pa. In that study, rat pups whose dams received PFOA experienced delays in maturation and increased mortality. At the lowest dose with observed effects, the male pups lost weight, and this indicator was used for the risk assessment. Significantly, the difference between the PFOA rat dams’ blood concentrations and those measured in the blood from groups of children and women is
less than 100-fold. This is a slim margin of safety that could be a cause for serious concern, say experts. However, using the concentration of PFOA in the male rats’ blood gives a difference of more than 9000, because female rats eliminate the perfluorinated compound much quicker than the males. The EPA preliminary risk assessment is at odds with a risk assessment published in August 2002 by the West Virginia Department of Environmental Protection. The state’s assessment evaluated many of the same studies but decided that effects to the liver were of most concern and concluded that current environmental concentrations of PFOA pose no risk to human health. The West Virginia assessment stemmed from a consent order between the state and DuPont, following the discovery of PFOA from the company’s facility in public water supplies there, and in nearby Ohio. A panel of toxicologists, including several from EPA, proposed a reference dose of 0.004 milligrams per kilogram body weight per day. This converts to a drinking water concentration of 150 parts per billion—much higher than any currently known environmental concentration, assuming a 60 kilogram adult drinks 2 liters of water each day. EPA’s effort to negotiate binding research agreements with companies that manufacture and use
PFOA, as well as companies that manufacture telomers, began with letters of intent that were released on April 14. The members of the Fluoropolymer Manufacturers Group (Asahi Glass Fluoropolymers, USA; Daikin America; DuPont; and Dyneon), who together represent most of the known users and manufacturers of PFOA, outlined in these letters of intent to reduce emissions from their plants that use or manufacture PFOA by a minimum of 50% by 2006 as compared to a baseline determined in 2002. Another group of companies has formed the Telomer Research Program (TRP—Asahi Glass, Clariant, Daikin, and DuPont). These companies are involved because there is some evidence that telomers can degrade to PFOA. TRP has hired a research lab to analyze for PFOA in finished carpets, textiles, and paper products that use telomer compounds. A report of the findings is expected this summer. Analysis of used products is expected before the end of the year. Although DuPont maintains that existing data do not show an association between PFOA exposure and adverse human health effects, the company is continuing its study of the compound and has been working with federal and state agencies to determine human healthbased screening levels for PFOA, according to a company spokesperson. —REBECCA RENNER
For the first time, lakes in New York state’s Adirondack Mountains are showing signs of the long, slow crawl back to recovery from acidification, according to two new studies based on the same data set. Roughly 60% of lakes surveyed in the Adirondack Mountains, the United States’ most acid-sensitive region, displayed a significant increasing trend in acid-neutralizing capacity, reports Charlie Driscoll, environmental engineer at Syracuse University (Environ. Sci. Technol. 2003, 37, 2036–2042). In addition,
acid-neutralizing capacity is increasing in waters of the Appalachian Mountains, from Virginia to New York, and in the Upper Midwest, demonstrating for the first time in the United States that mandated cuts in emissions of acid rain-generating SO2 can lead to region-wide ecosystem recovery, concludes a January 29 U.S. EPA report (www. epa.gov/ord/htm/CAAA-2002report-2col-rev-4.pdf). Driscoll and his colleagues took a detailed look at trends in acid deposition and acidity of 16 lakes
202 A ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / JUNE 1, 2003
CARL HEILMAN II/WILD VISIONS, INC.
Adirondack lakes recovering from acid rain
Acid-neutralizing capacity is increasing in Adirondack lakes.
monitored since 1982 and 32 lakes monitored since 1992 in the Adirondacks. They measured a significant increasing trend in acid-neutralizing capacity of 1.60 microequiva-
sis is that increases in CO2 from fossil fuel burning are boosting the growth of plants, which are sequestering the nitrogen, he says. But the flow of acidic nitrate ions to the lakes may increase if the forests become saturated with nitrogen and can no longer store it, or if climate change events, such as droughts, lead to fires that release nitrogen from the watershed. Although most lakes are improving, 40% show no change or continue to lose acid-neutralizing capacity, Driscoll cautions. With the controls now in place that will cut SO2 emissions by 50% from 1980 levels, full chemical recovery of Adirondack lakes to an acidneutralizing capacity of 50 µeq/L will take 25–100 years, he says. Because the acid rain controls in the Clean Air Act do not cap NOx emissions, watersheds will continue to receive far more than the 8 kilograms nitrogen per hectare per year that is considered safe for sensitive watersheds. To stop leaching of nitrate from watersheds, NOx emissions from utilities must be cut by 75% in concert with aggressive cuts in passenger car emissions of nearly 90% beyond levels mandated for model year 2004, Driscoll reports (BioScience 2003, 53, 357–374). Europe and Canada, with emissions cuts similar to those in the United States, have also measured a growing number of lakes regaining their acid-neutralizing capacity, says John Gunn, fisheries research scientist at Laurentian University. This has spurred a further 80% cut in emissions of SO2 and NOx in European countries by 2010, he says. And the Canadian provinces of Nova Scotia, New Brunswick, Quebec, and Ontario have agreed to cut SO2 emissions a further 50% from current levels by 2010 and will agree on NOx cuts by year’s end, says Kerri Timoffee, manager of the acid rain program for Environment Canada. Meanwhile, the Bush administration’s proposed Clear Skies legislation would cut SO2 emissions by 73% and NOx emissions by 67% from 2000 levels by 2018. —JANET PELLEY
News Briefs Taking the heat off data centers A new “smart” modeling system for designing the data centers that house hundreds of computers could save millions of dollars in energy bills each year, according to the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy. The new modeling system was created by the computer giant HP and relies on computational fluid dynamics, which have been used to improve airplane designs, to create a threedimensional model of the temperature distribution throughout a data center. “Increasingly powerful microprocessors and systems are leading to higher heat densities in data centers,” says Juergen Rottler, vice president with HP Services. HP researchers believe their smart cooling analysis could reduce expenses at a 30,000square-foot data center by as much as 25%. For more information, go to www.eere.energy.gov.
Top and worst charities The Sierra Club and the Scenic Hudson Land Trust were among environmental organizations earning a top rating of four stars from Charity Navigator, a nonprofit group that ranks U.S.-based charities based on their publicly available tax filings. On the other hand, The Cousteau Society and Earthvoice International both received zero stars. Overall, Charity Navigator ranked 213 environmental organizations, awarding 79% of them four stars. The ratings were based on factors such as each group’s fundraising, program, and administration costs and how much they spend to raise each dollar by fundraising. To check on 1900 nonprofits, go to www.charity navigator.org.
JUNE 1, 2003 / ENVIRONMENTAL SCIENCE & TECHNOLOGY ■ 203 A
PHOTODISC
lents per liter per year (µeq/L-yr) from 1992 to 2000 for 29 of the 48 monitored lakes. The lakes ranged from chronically acidic, with no acid-neutralizing capacity, to those that are nearly impervious to acid rain and have an acid-neutralizing capacity well over 50 µeq/L, which is the threshold over which aquatic plants and animals are safe from the effects of surface water acidification. Driscoll’s findings provide more detail than the EPA study but confirm EPA’s findings of a widespread improvement in lake chemistry due to SO2 emissions cuts, says John Stoddard, aquatic ecologist at EPA and author of the EPA report. Acid-neutralizing capacity is a key indicator of recovery because it measures the ability of a watershed to counteract the acid pollutants, nitric and sulfuric acid, in rainfall, says Stoddard. These acids form when NOx and SO2 from fossil fuel combustion react with atmospheric water. The positive trend in acid-neutralizing capacity in the Adirondacks is due to drops in the acid anions sulfate and nitrate, which are declining at a rate of –3.26 µeq/L-yr, Driscoll says. The decrease in sulfate ions in lakes matches the decline in emissions of SO2 and deposition of sulfate in rain and snow, he adds. This clearly demonstrates that the region-wide cuts in SO2 mandated by the Clean Air Act can help lakes over a wide area recover, he says. Emissions of SO2 have declined 38% since their peak in 1973. Another positive sign is the growing concentration of dissolved organic carbon (DOC) in 7 of the 48 lakes, Driscoll reports. The return of DOC helps shift aluminum from its toxic inorganic form toward less toxic organic forms. However, because DOC is associated with naturally occurring organic acids, it could slightly retard recovery of acidneutralizing capacity, he says. But scientists are baffled that concentrations of acidic nitrate ions are decreasing in the lakes, while emissions of NOx and deposition of nitrate ions have remained relatively constant over the study, Driscoll says. The leading hypothe-
