On Another Planet

You won't believe it until you read it. With its recently released report titled "Mercury in Perspective: Fact and Fiction About the Debate Over Mercury”, the GOP leadership of the House Committee on Resources has brought scientific debate on an already politicized issue to a new low.

The 33-page document, issued by anti-environmentalist committee Chair Richard Pombo and fellow Republican Jim Gibbons of Nevada, is billed as a "comprehensive synopsis of the federal agency, private and recently peer-reviewed research used in the debate over regulating mercury." In fact, it's a misleading contrarian pamphlet aimed at convincing Americans that despite everything they may have heard, mercury levels in fish aren't dangerous and U.S.-based mercury emitters aren't a significant part of the problem.

In order to achieve this feat, the Pombo report has to run roughshod over much of what we know about mercury risks from reliable sources like the Environmental Protection Agency (EPA) and the National Academy of Sciences (NAS). Instead, the report turns to industry and think-tank opinion. Of its 59 references, 14 cite industry sources like the Edison Electric Institute and Electric Power Research Institute or conservative think tanks like the Center for Science and Public Policy (CSPP) at Frontiers of Freedom (which calls the basis for any regulation of mercury from power plants "questionable"). Indeed, compare Figures 1 and 7 from the Pombo report with Figures 1 and 3 from this CSPP document -- you may note some similarities.

Mercury is a naturally occurring heavy metal released in coal burning. Emitted into the atmosphere from electric utilities and other sources, mercury eventually winds up being deposited back on land or in bodies of water, where microorganisms convert the less reactive elemental mercury into methylmercury, a strong neurotoxin. Methylmercury makes its way up the aquatic food chain and bioaccumulates in predatory fish; humans are then exposed through fish consumption. Pregnant mothers run the gravest risk, as their consumption of mercury-tainted fish can lead to neurological damage in their children.

This much scientists know, but as with any environmental issue, complexities exist. First, mercury emissions have natural as well as industrial origins. And while some mercury falls close to the site of its origin, mercury can also travel the globe, making it difficult to pinpoint exactly where releases from a given power plant actually end up.

In essence, Pombo and Gibbons seek to exploit these and other scientific uncertainties in order to downplay mercury risks and, therefore, the case for strong regulation. The Pombo report questions whether mercury from fish actually has serious toxicological effects, argues over whether U.S. emissions really play a big role in domestic mercury contamination, and hypes natural sources of mercury as if these somehow make industrial emissions less troubling. Consider some of the report's claims:

"There has been no credible evidence of harm to pregnant women or their unborn children from regular consumption of fish."

To hear Pombo & Co. tell it, there are basically two major epidemiological studies on fish consumption worth considering: one from the Seychelles Islands finding no toxic effects and one from the Faroe Islands reporting neurotoxicity and developmental delays associated with mercury consumption. Given these two choices, Pombo's report then raises concerns about the Faroe study and implies that mercury risks should be reassessed based on the Seychelles study.

In fact, Pombo and Gibbons have stacked the deck by creating the appearance of an opposition between two studies, rather than examining the broader range of data. By contrast, in 1999 the NAS convened an expert panel and considered the total weight of the evidence on the toxic effects of methylmercury. In a 300-page report, the NAS panel noted that because a wide range of studies all suggested a risk, it could hardly rely on the one study that didn't. But it seems that's precisely what Pombo would have us do.

"Current, peer-reviewed scientific literature does not show any link between U.S. power plant emissions and mercury in fish."

It's unclear exactly what the Pombo report means by "current, peer-reviewed scientific literature," but it appears to be demanding direct scientific proof that atoms of mercury from a specific source end up in a specific place. But given the complexities of mercury cycling, that's an unreasonable request. "There's probably nobody who has said that the mercury in this fish came from that power plant," explains Peter Weiss-Penzias, a research scientist at the University of Washington-Bothell who has published on the cycling of mercury. "You just couldn't support that conclusion scientifically."

That doesn't mean you can't draw some inferences, though. Indeed, in late 2000 the EPA estimated that "roughly 60 percent of the total mercury deposited in the U.S. comes from U.S. anthropogenic air emission sources" (a figure the Pombo report never explicitly challenges). Due to remaining uncertainties, the EPA admitted it couldn't precisely quantify how much mercury in fish consumed in the United States comes from domestic plants. Nevertheless, the agency found that electric utility emissions represented a "substantial portion of the environmental loadings," and that a "plausible link" existed between such emissions and contaminated fish. In short, EPA chose to act on the basis of available knowledge -- which pointed to a real, if inadequately quantified, risk -- rather than subjecting Americans to ongoing dangers as it waited for more data.

"Mercury is a naturally occurring element that is ubiquitous in the environment."

Another technique used by Pombo et al is hyping natural sources of mercury as if their existence should somehow reassure us about power-plant pollution. For instance, the committee cites a 2003 study of sediments deposited in Minnesota's Elk Lake, which found "many intervals during the past [8,000 years] when natural processes produced mercury accumulations greater than the modern anthropogenic accumulations." The Pombo report claimed this work showed that "anthropogenic (man-released) emissions have not been significant or exceptional," but that's a misinterpretation. While the study did find naturally caused mercury spikes in past eras, its lead author, William F. Cannon of the U.S. Geological Survey, says, "The fact that they occurred naturally doesn't make the present anthropogenic spike any less dangerous just on those facts alone."

In fact, the very same paper explains that Elk Lake sediments "record the widely recognized trend of increasing concentration and accumulation rate of mercury … a trend almost universally accepted as a reflection of increased anthropogenic release of mercury to the atmosphere." Just how strong is the evidence of that trend? "Almost every lake sediment core that I've ever seen reported -- there's dozens if not hundreds of papers on them -- you always see a rapidly escalating increase in mercury," explains Cannon.

Why does all this matter? Just before George W. Bush's inauguration, Bill Clinton's EPA moved to stringently regulate mercury emissions by demanding that utilities employ the "maximum achievable control technology" to cut pollution. But the Bush administration fell back on a much more lax course, proposing a market based "cap and trade" approach in late 2003. Next month, the Bush EPA will have to finalize its regulation, a decision Pombo's report seems clearly timed to influence.

Pombo & Co. officially come out in favor of cap and trade, but there's a disconnect: Reading their report gives the impression that there's no reason to regulate mercury at all. Indeed, a cynic might even suspect Pombo and Gibbons of staking out an extreme denialist position on mercury risks to make the Bush stance seem more moderate and reasonable. That would be a clever strategy, certainly -- provided you don't mind treating scientific information about risks to American children as a political football.

Chris Mooney is a Prospect senior correspondent whose TAP Online column appears each week. His book on the politicization of science will be published later this year by Basic Books. His daily blog and other writings can be found at www.chriscmooney.com.