Citing a 1998 report to Congress on hazardous air pollutants released by utilities and another by the Electric Power Research Institute, utility officials say their emissions are at levels that do not pose a public health threat. On its Web site, Southern Co., the largest electricity producer in the United States, seeks to reassure customers that its utilities' releases pose no harm. Other utilities have included fliers in billing statements asserting that the company is in "full compliance with all local and federal emission standards" "The key is in trying to let the public know what the numbers mean," added Janni Benson, Southern Co. spokesperson. The trick in this approach is making a distinction between hazard and risk, which can be hard to communicate when interest groups use "hazard" without referring to an individual's risk, said George Gray, deputy director of the Harvard Center for Risk Analysis at the Harvard School of Public Health. Although a substance III 3.V be toxic the exposure to tin individual may not be enough to negative effect, said Gray. "The TRI ignores the sciences of toxicology and exposure assessment, which are essential when considering risk." In addition, the 43% drop in all emissions in some cases represented a drop in releases of toxic substances that are not as hazardous as others. Other companies may have replaced the TRI-listed chemical with one that lacked adequate toxicology mtormation, he aoQeo. Gray and the utilities are not the first to call for the TRI to include risk information. "Other [TRI] facilities have asked EPA to do this all along," said Mayer. In May, an independent advisory group sent Browner a report recommending steps to improve the TRI, including adding scientifically valid information on hazard, risk, and exposure. EPA staff insist that the 1998 study does not state that all utility TRI emissions pose no threat. They add that the law puts the job of interpreting the TRI in the hands of local communities, many of which have conducted
their own risk assessments. Asking the agency to centrally conduct risk assessments for all 630 TRI substances would be financially impossible, and the results would be too broad to be of use, the staffers added. One TRI substance that will not appear in next spring's reports is mercury, because most power plants' emissions are well below the TRI threshold. Based on new non-TRI data from utilities on mercury, the NRDC plans to develop reports pinpointing the mercury risk that a particular community has from the nearby power plants, Silva said. —CATHERINE M. COONEY
DID YOU KNOW? "Less than half of the 76 utilities operating nuclear power plants in the United States have accumulated suffi cient funds to close them." (Source: U.S. General Accounting Office)
Consensus on health risks from mercury exosure eludes federal agencies Two federal agencies, EPA and the Agency for Toxic Substances and Disease Registry (ATSDR), are still at loggerheads over health advice regarding methylmercury. A special meeting convened by the White House Office of Science and Technology last November to try to resolve the conflicts between these and other federal agencies {ES&T 1998, 32(19), 444A-^445A) has resulted only in the acknowledgement that a range of recommendations is acceptable, according to individuals interviewed about the workshop's final report. The differences between the agencies' health recommendations are small. EPA currently recommends 0.1 microgram per kilogram of body weight per day (pg/kg/day); ATSDR recommends 0.3 pg/kg/day; and the U.S. Food and Drug Administration's (FDA's) standard of 1 part per million in fish is roughly equivalent to 0.5 pg/kg/day. But the lack of harmony between the agencies' health advisories impacts several programs: state fish advisories, which affect consumption of noncommercial fish; commercial fish sales; and regulatory decisions about controlling mercury emissions from electric power plants Much of the conflict arises from two recent noncorroborating epidemiological studies of children living in the Seychelles
Islands and the Faeroe Islands. These studies were reviewed at the November meeting with a goal of achieving more harmonized federal health advice. However, the expert panels convened at the November workshop concluded that both studies are credible and well done, given the difficulty of teasing out such information, said George Lucier, director of the National Institute of Environmental Health Sciences Environmental Toxicology Program and workshop co-chair. Despite this assurance, exposure levels that have no detrimental effects in the Seychelles produce detrimental effects in the Faeroes, Lucier said. The report will show that both might be correct since the studies used different developmental tests. The Faeroe Islands study, for example, used tests more sensitive to effects of mercury than the Seychelles study, he said. "The Seychelles study may underestimate risk, while the Faeroe Islands study may overestimate it," Lucier said. And different plausible assumptions used in risk calculations can result in the range of current recommendations, he added. The final workshop report was being prepared for publication as ES&Twent to press. In April, ATSDR revised its recommended safe level for methyl-
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mercury exposure to 0.3 pg/kg/day. This level is down slightly from the 1997 draft recommendation of 0.5 mg/kg/day (ES&T1998, 32(1), ,A). But ATSDR's reasoning seems to have litde to do with compromise. As in the draft recommendation, its analysis is based on the Seychelles study, including new data from Seychelles children at 62 months of age. However, the fined recommendation did include an evaluation of the Faeroe Islands study, which influenced die uncertainty factors that ATSDR used, according to ATSDR Division of Toxicology Director Christopher De Rosa ATSDR officials believe that the Seychelles study is most relevant to the U.S. population, De Rosa said, and that the neurodevelopmental delays documented in the Faeroe Islands come from exposure to polychlorinated biphenyls and other organochlorine compounds. When ATSDR released its new advisory, officials there emphasized the health benefits for Americans from eating fish, a point on which all public health officials agree. But for the first time, ATSDR made a distinction between the exposure to mercury from consuming commercial fish, which it says is low, and exposure to higher levels of mercury in fish caught in lakes and rivers. The agency also suggested that subsistence fishermen be particularly cautious about fish consumption. Meanwhile, EPA is standing firm behind its reference dose of 0.1 ug/ kg/day, according to Carl Mazza in the Office of Air and Radiation. EPA is restricted from taking any regulatory action to curb mercury emissions until the National Academy of Sciences (NAS) evaluation of EPA's reference dose is completed The review, which is scheduled for completion in May 2000, will includi a reassessment of the literature on mercury, including the Seychelles Island and Faeroe Island studies. EPA is under a court order to decide bv December 2000 whether mercurv emissions from coal-fired plants should be regulated Toxicologist Robert Goyer heads the 11-member NAS committee of epidemiologists, toxicologists, and experts in statistical design, which held its first meeting last month. —REBECCA RENNER
New research challenges fertilizer as cause of coral reef declines An unexpected research finding hinting that dramatic coral reefs losses in the Florida Keys are not caused by nutrient overenrichment is being called into question because it challenges the prevailing belief that human activities, such as coastal development, pollution, and overfishing, threaten 58% of the world's reefs. At the National Coral Reef Institute conference in April, Mark Hay, an ecologist at the Georgia Institute of Technology, presented findings showing that fertilizers do not boost the growth of seaweeds that compete with corals. Hay's experiments added nutrients to coral reef plots in Florida both near and far from human development. Contrary to expectations, at all sites he observed no
increase in seaweed growth. "This indicates that the seaweeds are not nutrient-limited, and that nutrients are not the main factor causing declines of corals," Hay said. But John Ogden, a marine ecologist at the University of South Florida in Tampa, disagreed, saying that fertilizing reefs with nutrients increases the growth of seaweeds, which shade and crowd out the corals. "A healthy reef is a balance between the corals that form the reef and the seaweeds that grow on the reef," he stated. Hay's inorganic nutrient additions did not match the organic forms delivered in sewage and stormwater runoff, he added, claiming that Hay's nutrient spikes XATPfP t " 0 o small and
Coral reef project aims to pinpoint hot spots Scientists from the United States and Australia launched a joint effort to improve coral reef monitoring and predict bleaching events at an international conference in Hawaii in June. The new effort pairs satellite and expert system observations from the National Oceanic and Atmospheric Administration (N0AA) with on-site data from two Australian research institutes. "The goal is to quantify sea surface temperatures using satellite data and see how precisely they predict bleaching of corals," explained Al Strong, an oceanographer with N0AA. If scientists can post predicted locations of hot spots on the Internet, reef managers can act to reduce other stressors such as recreational fishing and boating, Strong said. Strong has been able to predict bleaching events over broad general areas since 1997, using ocean surface temperature measurements from satellites. In 1998, Strong documented hot spots following an El Nino event that drove the world's most extensive coral bleaching and die-off to date. Every major reef area except the Central Pacific was hit, with mortality as high as 90% in parts of the Indian Ocean. Corals have a narrow range of temperature tolerance, and the high water temperatures associated with events like the 1998 El Nino can leave corals vulnerable to disease, damage, and death. When ocean temperatures exceed 28-30 °C, corals become stressed and eject the algae that live inside them and give them their color. Without the food that the algae provide them through photosynthesis, the corals appear bleached and can starve, Strong said. The increased ocean temperature predicted to accompany global warming means that bleaching and mortality may worsen in the years ahead, said D. James Baker, N0AA administrator. Predicting and assessing hot spots also will help scientists identify which reefs to monitor intensively and evaluate how temperature, ultraviolet light exposure, turbidity, and weather interact to cause bleaching. N0AA scientist Jim Hendee has developed computerized expert systems that scan U.S. and Australian weather data and post Internet alerts when conditions are conducive to coral bleaching. —JANET PELLEY
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