The Mercury Rule Work Group met for the second time this week to continue the information gathering phase of the Department of Environmental Protection’s effort to develop a Pennsylvania-only rule to limit mercury emissions from power plants.

The group heard presentations from—

· Dr. John Bell, Safrisk, LC, who spoke on the health effects of the atmospheric release of mercury from combustion sources;

· Dr. Terry Sullivan, Brookhaven National Laboratory, presented the results of studies on the impacts of mercury emissions on local deposition and human health risk;

· Dr. Donald McGraw, M.D., gave an overview of the human health affects of mercury;

· Wick Havens, DEP, reviewed past and likely sulfur dioxide and nitrogen oxide emission reductions in Pennsylvania as a result of the new federal clean air rules; and

· Aaron Frey, DEP, made a presentation on Pennsylvania’s fish advisory and sampling program.

Dr. McGraw agreed with speakers at the first Work Group meeting who said mercury exposure through ambient air and water exposure did not pose a significant toxicological risk to the general population. Mercury in fish and the food chain is the route of exposure to humans.

As a practicing physician, Dr. McGraw said his review of the literature shows the human dose limits for mercury set by the U.S. Environmental Protection Agency were set at an “impractically low level” because studies have not shown health affects at those levels.

“Studies of people eating lots of fish in other cultures do not show adverse health consequences,” said Dr. McGraw. “There is a huge benefit to eating fish and it would be an unfortunate tradeoff to reduce the consumption of fish for health effects we haven’t seen.”

Dr. McGraw did say he was always more cautious with certain groups like pregnant women on reducing risks. But his advice is “keep eating fish” and “follow the (fish) advisories.”

Pennsylvania currently has a statewide advisory to eat no more than one-half pound of sport fish per week and specific advisories on certain lakes and streams.

Dr. Sullivan addressed the issue of mercury “hotspots” by reviewing the results of studies Brookhaven did with several power plants which demonstrated no correlation between the predicted air deposition patterns around the plants and mercury levels in soil and vegetation based on actual sample results.

“There is also no conclusive data on the link between mercury deposition from the air and mercury levels in fish,” said Dr. Sullivan. “We didn’t see enough deposition any where from power plants to increase the levels of mercury in fish. The only correlation we saw in one case was with a highway where higher mercury levels followed a clear linear pattern.”

Dr. Sullivan noted that the characteristics of a water body, like whether it is fast or slow moving or the temperature of the water, has more to do with the conversion of mercury to methyl-mercury, the form of mercury that is associated with health risks, than air deposition.

Brookhaven’s health risk assessment studies also concluded that it would take a 40 percent reduction in the air deposition of mercury to achieve “much less than a 1 percent reduction” in human health risks in the general, non-subsistence fishing, population.

The 90 percent reduction in mercury emissions from power plants being suggested by DEP would yield about a 10 percent reduction in mercury air deposition, according to Dr. Sullivan.

The federal mercury reduction rule now in effect would result in an 86 percent reduction in mercury emissions from power plants.

Dr. Bell’s presentation reviewed the human health conclusions from several studies involving methyl-mercury exposure and populations on isolated islands that depended on fish as a primary food source. The study results have been mixed and all involved consumption of fish and mammals from the ocean.

A study of the population on Faroes Island northwest of Scotland showed some developmental effects, however, that study was complicated by the fact the population was also exposed to PCBs. Another study of the Seychelles Islands in the Indian Ocean suggested an improvement in development parameters. A study in New Zealand followed mother-infant pairs that did show some dose-related developmental effects.

The next two meetings of the Work Group are set for November 18 and 30. At the November 18 meeting the agenda will include presentations on available mercury control technology and the cost-benefit analysis performed by EPA as part of the federal rulemaking process.

Copies of the presentations and other background information are available on the Mercury Rule Work Group webpage.

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10/28/2005