catchment runoff and 0.12 g/yr would enter it from atmospheric deposition. Whether the mercury in the runoff is newly deposited mercury, which has been shown to be more bioavailable than older mercury, or mercury that has been locked up in the soil for many years, is difficult to determine. “You have atmospheric deposition accumulating in these pools, and you’ve also got old mercury that’s been sitting in the pools. I think it’d be pretty tough to separate the two out without using isotopes,” says Lindberg. —BRITT E. ERICKSON
Concerns over common perfluorinated surfactant
RACHEL PETKEWICH
Perfluorooctanoic acid (PFOA), a perfluorinated surfactant produced in the United States by DuPont and used in the manufacture of Teflon, Goretex, and stain-resistant carpets, may pose a developmental risk to children at concentrations already found in the blood of women and children, according to a U.S. EPA preliminary risk assessment released on April 14. “The data before us raise concerns,” according to Steve Johnson, EPA’s Office of Pollution Prevention and Toxics assistant administrator, who announced that the agency is accelerating its investigation of
A perfluorinated surfactant used to make Teflon could pose a risk to children.
PFOA because of the analysis. The agency is also taking the unusual step of publicly negotiating enforceable consent agreements with the manufacturers and users to require research and reduce PFOA emissions. But the agency is not considering emergency action at this time because there is too much “scientific uncertainty” about the sources and pathways of PFOA exposure in the general population and too much uncertainty about the animal testing data, he said. PFOA, sometimes referred to as C-8, has widespread applications in chemical manufacturing, aircraft production processes, and some electronic products. Following the unexpected discoveries concerning the environmental fate and toxicity of perfluorooctane sulfonates (PFOS) (Environ. Sci. Technol. 2001, 35, 154A–160A), EPA began investigating PFOA. PFOA is a persistent pollutant and small concentrations are found in human blood, according to the risk assessment. Unlike PFOS, PFOA does not appear to biomagnify in animals. However, an ongoing, five-year study of nine retired 3M workers suggests a mean serum
News Briefs Public buses in Iceland fill up on hydrogen The world’s first public hydrogen fueling station opened for business in Reykjavik, Iceland, on April 24. The new station, which was produced collaboratively by Icelandic New Energy, Ltd., Daimler-Chrysler, and Shell, is a milestone toward Iceland’s goal to create the world’s first hydrogen economy. The station services three hydrogen fuel cell-powered buses running regular routes throughout the city. The buses fill up on compressed hydrogen gas produced by on-site electrolysis of tap water. The electricity required for this reaction is obtained from renewable, geothermal energy, which is widespread throughout the country.
Cleaning up snowmobiles By designing a well-performing snowmobile with lower emissions, less noise, and improved fuel economy, University of Idaho students won the annual Society of Automotive Engineers’ (SAE) Clean Snowmobile Challenge for the second year in a row. Held at Michigan Technological University in March, the contest drew students from 12 universities across the country to reengineer existing snowmobiles, which are notorious polluters. “The engineering challenge lies in the fact that teams are also judged on how well [the snowmobiles] perform and how much fun they are to ride,” according to the SAE. Idaho’s four-stroke engine-powered design placed first in the emissions, noise, and fuel economy categories. Other schools won the handling, braking, and acceleration categories. For more information about the contest, visit www.sae.org/students/snow.htm.
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these accelerated input rates [due to clear-cutting and soil treatment], would still dominate,” he says. Methyl mercury is a different story. “Methyl mercury is generally on the order of 1% [of the total mercury] in atmospheric deposition,” says Lindberg. As a result, the watershed area-to-lake area ratio can be much smaller and the contribution of methyl mercury from runoff will still dominate. According to Porvari, for a hypothetical forest lake with an area of 1 km2 and a catchment area of 10 km2, approximately 0.2 g/yr of methyl mercury would enter the lake from the
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
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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-
