ENVIRONMENTAL NEWS Controversial EPA mercury study endorsed by science panel
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comprehensive and longdelayed EPA report on mercury was largely endorsed by a special review panel of the EPA Science Advisory Board (SAB) Feb. 28. The 32-member panel recommended only minor changes in the seven-volume report, and several members urged that EPA forward it to Congress without further delay. Under the Clean Air Act, the report was supposed to be released in 1994, but it has been mired in controversy and criticism The 1700-page report is the most thorough review ever done of mercury sources, exposure, health effects, management, and risks to humans and wildlife. As such, it will serve as a technical reference guide for federal and state regulatory bodies, including EPA and the states, which establish fish consumption advisories, and the Food and Drug Administration (FDA), which sets acceptable mercury limits in commercial seafood. Mercury is the largest cause of U.S. health advisories for fish consumption (ES&T Aug 1199 D 331A) The report was referred to SAB last June by EPA officials after being criticized for overestimating mercury's neurotoxicological effects on children and developing fetuses. Critics charged that EPA scientists had ignored preliminary results of studies of mercury's effect on fish-consuming populations of the Seychelles and Faeroe Islands, which were showing little impact from mercury. However, SAB panel members strongly questioned the Seychelles results and noted that none of the Faeroe information has been officially made public The two-day review marked the third time outside scientists have backed the report. It was the most expensive single SAB review,
according to SAB staff, who expect the report to be on the administrator's desk by May. The report is a critical step in EPA's effort to develop a regulatory scheme to cut hazardous air pollutants (HAPs) emitted by electric utilities, according to Mary Nichols, EPA assistant administrator for air and radiation,
Nothing in the Seychelles or Faeroe Island health studies should lead EPA to revise the report, said Genevieve Matanoski, SAB chair who spoke to the SAB panel. Along with the mercury report, EPA must produce a report under the Clean Air Act on the impact and control options for HAPs emitted by utilities. The delay of the mercury report has forced EPA to release an incomplete
HAPs report that lacks mercury emission information, which Nichols said is the most important utility air pollutant. Coal-fired utilities and medical and municipal waste incinerators account for about 70% of all anthropogenic mercury emissions. Unlike incinerators, utilities face no proposed or final HAPs emissions regulations, despite generating about 20% of anthropogenic emissions. Because of the delay, Nichols told ES&T, EPA maa turn to control scenarios other than the Clean Air Act, such as cutting utility mercury emissions from a half-dozen or so of the "most significant polluters" and reiving on fuel switching or other technical solutions Electric utilities have been strongly critical of EPA's mercury report, as has FDA, the White House Office of Management and Budget (OMB), and other agencies in the Clinton administration (ES&T, April l196, p. 154A). Such differences among the "federal family," Nichols said, drove EPA to withhold the report from Congress and seek SAB review (ES&T, May 1996, p. 193A). The differences were primarily over conflicting studies of the health effects of methylmercury on neurological development of chil-
Annual anthropogenic mercury emissions EPA's draft mercury report catalogs known sources of atmospheric Hg emissions. Human activities account for more than 240 tons annually but, according to the report, an equal amount may be generated by other sources. Source
Tons
Medical waste incinerators Municipal waste incinerators Coal-fired utilities Commercial/industrial boilers Primary lead production Secondary mercury production Chlor-alkali manufacturing Portland cement Other manufacturing sources Area sources Other sources
65 55 51 ;•'•.-.,'
29
9 7.4 6.5 6.5 36 3.1 6.4
Percentage 27 23 21 12 3.7 3.1 2.7 2.7 1 1.3 2.5
Source: Draft EPA Mercury Study: Reeprt t t oongress (EPA-452/R-96-0010), JuJu 1996
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dren, especially those resulting from prenatal exposure. EPA based its reference dose calculation primarily on studies published in the mid-1970s of neurological changes in infants after an incident of methylmercury poisoning of grain, which occurred in Iraq in the early 1970s. The incident was short in duration but high in exposure, and a study was made of 81 children who were exposed in utero when their mothers ate contaminated bread. However, a 1996 study of a fisheating population in the Seychelles Islands found litde effect on the neurological development of some 1500 children exposed through maternal consumption of methylmercury in seafood When explaining the Seychelles study to the SAB panel, principal investigator Gary Myers of the University of Rochester was vigorously quizzed about elements of the study, particularly decisions to drop statistical outiiers from the study, some of whom had been exposed to higher levels of mercury. After two days of discussion among panel members, a consensus emerged that the EPA report should not be delayed because of the Seychelles study; to do so would give a "stamp of approval" that the study did not merit at this time. Panel member Joseph Jacobson, Wayne State University, and others urged EPA to continue to rely on the more seasoned Iraqi data and to buttress this data with other human and animal studies that they said supported its conclusions. SAB Executive Committee Chair Genevieve Matanoski, who co-chaired the review panel, said nothing in the Seychelles or Faeroe Islands studies should lead EPA to revise the report based on new health effects data at tiiis time. Several members said, however, that in a few years, when a study of five-year-olds in Seychelles is complete and the Faeroe study is published, EPA may review its report. SAB's decision leaves intact a contradiction in federal standards for safe mercury levels. EPA's reference dose is, in effect, four to five times more conservative than FDA's standard for mercury in seafood. FDA stands behind its
States need the EPA mercury report, and federal disagreements do not merit delaying it any longer, says Margaret Round, program analyst. Northeast States for Coordinated Air Use Management.
standards, but it is currently beginning its own mercury reassessment that will be in draft by late this year, according to an FDA scientist involved in the effort, who asked not to be identified. FDA's current standard is based on adult exposure, not exposure to a developing fetus. FDA is uncomfortable using the Iraqi data, although it would result in a standard similar to
"We are coming to a point of convergence on mercury's potency." —Margaret Round, Northeast States for Coordinated Air Use Management EPA's. The Iraqi study is based on a grain-poisoning incident, the FDA scientist noted, which resulted in very high mercury exposure of short duration. Seychelles mothers had mercury levels of one-half or less those of Iraqi women. Because of the scale of exposure and the route (bread rather than fish), the official said, FDA is unwilling to use the Iraqi data to set seafood standards. Instead, FDA—a Seychelles study sponsor sees the Seychelles data as more applicable to real-world exposure in a fish-eating culture The official noted that the data show no impact in the first 29 months of life for children whose mothers consumed an average of 12 seafood meals a week during pregnancv
"We are concerned about the fetus, but what we are saying is: 'What data are we going to use?' We've got to do it right, and we want to make sure we use the appropriate information," said the FDA scientist. Meanwhile, EPA officials say they are not sure when top agency administrators will release the study. When it was completed almost two years ago, OMB blocked its release to Congress. An EPA scientist noted that much will depend on OMB's view of the quality of SAB's review. The EPA staffer noted the agency has been "under tremendous pressure" to delay the report, not just from FDA but from utilities and the coal and fisheries industries and their allies in Congress, who don't want to see new mercury standards coming down the regulatory pipeline. "There is a certain irony here," the EPA staffer said. "The difference between FDA and EPA is not that big a deal. We are less than an order of magnitude apart, which is a small range of uncertainty for mis type of calculation." A similar point was made by state officials, who urged EPA to release the report. "We are actually coming to a point of convergence on mercury's potency. FDA and EPA are going in the same direction. We know a small amount of exposure is harmful to a developing fetus or a child," said Margaret Round, program analyst for Northeast States for Coordinated Air Use Management, an organization of Northeastern states. "The report could be incredibly useful to us," said Round, "because it holds a compendium of peer-reviewed information, especially for a state health department that has a million other things to do." A particular worry of Round's is the holdup of the report's exposure information. "Remember, risk equals potency times exposure. States are trying to limit exposure. Who eats what fish, at what age, how much fish, where does it come from? These and lots of other concerns have been studied and presented in the report that is now seen as tarnished for other reasons." JEFF JOHNSON
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