Environmental▼News itors during two 48-hour periods in 1999. The students’ personal measurements for the metals averaged much higher than ambient levels or measurements taken in their homes and school. “The interesting thing about this study is that we were able to identify the biggest source of exposure,” says Sonia Sax, a research fellow at the Harvard School of Public Health, whose doctoral work was part of the TEACH study. The ratios of iron and manganese from the personal measurements suggested a steel source. The time and activity data revealed that the students were exposed to higher levels of airborne metals while commuting, and the researchers recognized steel dust from the subway rails as the likely source. “This study shows the importance of testing personal exposures. Doing ambient monitoring, you never would have seen the trend,” says Chillrud. A separate set of measurements taken exclusively in the subway confirmed that exposure there is considerably
higher than ambient or indoor exposure. “We do need to further characterize these exposures,” says Sax. “There are a lot of good epidemiological studies with humans involved, but they are mainly occupational and you can’t extrapolate to low dosages.” The current regulations for iron, chromium, and manganese are based mainly on high-dose studies and on animal studies. Chillrud is heading up a new study of subway workers to determine whether inhaling the metals actually affects the levels in the body. The aim is to establish whether there is a dose–response relationship between inhaled steel dust and measurable biochemical markers. Despite the findings, the subway remains a good alternative to other forms of transportation for NYC’s 1.3 billion annual riders, say the researchers. For example, according to Sax, the volatile organic compounds from surface traffic measured in this study present a greater
lifetime risk for cancer than do the subway metals. “The methods used by Chillrud et al. are some of the more elegant I have seen amongst several similar studies in various cities throughout the world,” says Roy Colville, a scientist from London’s Imperial College, who has done comparable work and reviewed the TEACH study. Although subway riders will inevitably inhale some dust as they wait for their trains, Colville argues that this prospect should not deter anyone. “An underground railway is a heavy engineering activity carried out in a confined space with members of the public present, so it is inevitable that some exposure to tunnel dust will occur,” he explains. “Good management of a first class service includes taking proper account of environmental, health, and safety matters in an integrated manner.… But we also need to take care to avoid getting too hysterical about the dust problem, which will take some time to solve.” —DEIDRA ROBINSON
Deca PBDE flame retardant gets around
MIRIAM DIAMOND
pounds, or congeners, on windows in residential and commercial An analysis of the organic film that ing that she sometimes refers to as buildings in and around Toronto. adheres to windows published in “window goo”—has potential to be Craig Butt, a graduate student in this issue of ES&T (pp 724–731)] reused as a cost-effective method for Diamond’s lab, found that brominatveals surprisingly high levels of the monitoring air pollutants. “These ed diphenyl ether-209 (BDE-209), Deca polybrominated diphenyl grimy layers trap more than what the major component of the Deca ether (PBDE) flame retardant. you would suspect,” Diamond says. brominated flame retardant mixture Because the sum of all the PBDEs Diamond’s research team most used in electronics equipment and measured in the films was up to 63 recently measured the concentraon some textiles, dominated the times higher than the levels of tions of 41 individual PBDE commixtures of PBDEs. BDE-209 reprePCBs on every sampled sented nearly 60% of the window, the study’s au14 PBDEs measured in thors say the films may significant quantities in foretell a continuing rise outdoor window films in PBDE levels. and almost 50% of these The paper’s lead author, PBDEs on the insides of Miriam Diamond of the the windows, according to University of Toronto’s gethe researchers’ normalography department, has ized calculations. become well known for her “Up to now, most research into the toxins studies on PBDEs have that adhere to impervious focused on the lower molsurfaces like sidewalks, ecular weight congeners roads, and windows. She of the Penta formulation, believes that the greasy primarily because these film on windows—an 11− are abundant in the gas A study of the organic film on both the insides and outsides of windows reveals high levels of Deca PBDEs. 100-nanometer-thick coatphase and are believed to 50A ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / FEBRUARY 1, 2004
cause window films respond more quickly to contaminant increases than other biota-like animals that concentrate toxins in their fat over time, the results can be interpreted as a sort of early warning of rapidly rising PBDE levels, they say. In the Toronto study, the levels of PBDEs in films on indoor windows were up to 20 times greater than on outdoor windows. “The high levels in indoor air certainly could impact human exposure,” says Linda Birnbaum, director of the Experimental Toxicology Division of the U.S. EPA’s National Health and Environmental Effects Research Laboratory. She says that as-yetunpublished studies of the PBDE levels in food indicate that air could be an important exposure source. Rain is likely to wash a large portion of the BDE-209 captured in the window films into urban surface waters, according to the researchers. The paper reveals an important source of the PBDEs in aquatic ecosystems, says Michael Ikonomou, a research scientist with Fisheries and Oceans Canada and a paper coauthor who has documented high levels of PBDEs in fish from pristine areas (Environ. Sci. Technol. 2003, 37, 240A−241A). The paper also suggests that the heavier PBDEs may be debrominated to create lighter PBDEs. “The high concentration of BDE-209 may indicate a steady-state situation between inputs (from source) and outputs via photolytic debromination [or] volatilization of the resulting lower brominated, higher vapor pressure congeners, and wash-off of heavier compounds to surface waters,” Diamond says. —KELLYN S. BETTS
Streamlining radioactive waste disposal In the future, waste that contains small amounts of radioactive materials could find its way into hazardous waste or even municipal landfills under regulations being considered by the U.S. EPA. Such “low-activity” radioactive waste (LARW) contains small enough concentrations of radionuclides that it may not require
the same radiation protection measures as those governing spent nuclear fuel or other high-level radioactive waste, according to the advance notice of proposed rulemaking (ANPRM) released by EPA officials in late November. Currently, LARW has to be stored at one of the country’s three com-
News Briefs Mercury dumping in India? Imports of mercury to India have seen a sixfold increase in seven years, according to the Center for Science and Environment (CSE), an active environmental group in New Delhi. The mercury imports come mainly from Spain, Britain, Russia, Italy, and the United States; CSE alleges that developed countries are exploiting India’s lack of regulation to dump their unwanted mercury products. The mercury is used by India’s chlor-alkali and electrical industries. India has outstripped the United States in mercury consumption, using up to 1843 tonnes per year, which is half of total global production, according to CSE. For more information, go to www.cseindia.org/ dte-supplement/mercury-index.htm.
Mercury drops in wildlife Mercury levels in Everglades fish and birds have dropped by 80% over the last 10 years, according to a study by the Florida Department of Environmental Protection (DEP). DEP attributes the decline to the U.S. EPA’s aggressive controls on mercury emissions from garbage burners, medical waste incinerators, and sugar processors; because of the controls, emissions have dropped more than 90% since the early 1990s. The results prove that local controls can yield dramatic results over a short period of time, says DEP. In addition, although South Florida has no coal-fired power plants—a major mercury source— and it is easier to control the watersoluble mercury from incinerators, the study indicates that pollution controls could cut levels of mercury in the environment nationwide. Integrating Atmospheric Mercury Deposition and Aquatic Cycling in the Florida Everglades is at www. dep.state.fl.us/secretary/comm/ 2003/nov/pdf/mercury_report.pdf.
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USGS
be the most susceptible to longrange transport. BDE-209 is extremely involatile and will exist in the atmosphere almost entirely associated with particles,” says Tom Harner, a research scientist with Environment Canada, the country’s environmental protection agency. “Somehow the BDE-209 particles are making it into the atmosphere and moving around…. We need to better understand the fate and transport of particle-associated chemicals such as BDE-209,” he adds. The Deca flame retardant mixture is under increasing scrutiny, in part because the main North American manufacturer of the other two PBDE mixtures used to protect consumer goods, Penta and Octa, agreed to voluntarily discontinue those mixtures last November (Environ. Sci. Technol. 2004, 38, 14A). The Penta and Octa mixtures are slated to be banned in Europe and California. “The observation of BDE-209 dominating the PBDE congeners present seems at odds with industry dogma that Deca does not escape finished products readily,” says Rob Hale of the Virginia Institute of Marine Science. “This finding is in agreement with the high levels in house dust, however,” he adds (Environ. Sci. Technol. 2003, 37, 407A−411A). The University of Toronto researchers’ finding that the total PBDE concentrations were higher than the PCBs measured in every study sample is notable because almost all studies of the two compounds in the environment show that PCB levels are much higher, according to the researchers. Be-
