Reconsidering U.S. EPA’s Proposed NESHAP’s Mercury Emission Rule
“The proposed rules will have little, if any, impacts on mercury concentrations in the environment at a very high monetary and societal cost.”
The Environmental Protection Agency’s (EPA’s) newly proposed National Emission Standards for Hazardous Air Pollutants (NESHAP) from Coal- and Oil-fired Electric Utility Steam Generating Units and Standards of Performance for Fossil-Fuel-Fired Electric Utility, Industrial-Commercial-Institutional, and Small Industrial-Commercial-Institutional Steam Generating Units”1 failed to describe the scientific reality of natural processes and multi-factorial controls that govern the cycling of mercury (Hg) and the ultimate biomethylation and bioaccumulation processes for methylmercury (MeHg). As this report documents, this natural cycle has been taking place for at least the last 650,000 years.
According to a new United Nations Environment Programme (UNEP) report on mercury,2 U.S. mercury emissions from all sources are indeed far lower than those of China and India. Indeed, an earlier EPA press release and webpage acknowledge that U.S. emissions are only “roughly three percent of the global total”and that from “1990 through 2005, [U.S.] emissions of mercury into the air decreased by 58 percent.”3
The ultimate question that EPA and the public should therefore ask then is this: What will we get by cutting our already very small U.S. mercury emissions from power plants and other man-made sources – especially since new estimates from peer-reviewed papers suggest that mercury emissions from U.S. forest fires alone release about 44 tons of mercury per year,4 an amount roughly equivalent to the annual emissions from all power plants in the United States today?
The bottom-line remains that trace amounts of mercury (Hg) or the biochemically-active form of methylmercury (MeHg) in fish, either from lakes and streams or oceans, are essentially a natural manifestation that has no clearly controllable relationship vis à vis any anthropogenic emissions of mercury. More importantly, consuming reasonable amounts of fish, at reasonable frequency, is safe and should be a crucial component of a healthy dietary plan for every Americans.
The proposed rules will have little, if any, impacts on mercury concentrations in the environment at a very high monetary and societal cost.
EPA’s proposed NESHAP provides no detectable beneficial outcomes in the control of mercury emissions (even accepting EPA’s own risk-benefit analysis without a challenge). The new rules will result in a major economic impact, harm American public health by creating exaggerated and unfounded fears about eating fish that are beneficial in everyone’s diet, and further degrade the essential role of science in informing public policy.
This report makes the following findings regarding EPA’s proposed new emission rules focusing on mercury:
(a) The EPA proposal is an extreme form of political advocacy, seeking to limit the already low levels of mercury emissions (relative to other anthropogenic and natural sources of mercury) from U.S. electric power plants. Because the agency neglects most other active mercury emission sources, the emission cuts EPA proposes for mercury in Electric Generating Units (EGUs) will be “all pain and no gain” for Americans’ public health. This fact can be demonstrated even by using the highly exaggerated risk-benefit analyses reported in this EPA proposal.
(b) The EPA proposal failed to highlight that its risk-benefit calculation, claiming an overwhelming benefit of $5 to $13 in benefits per dollar spent on emission controls, was dominantly derived from the “co-benefits” of PM2.5 control.5
In dollar terms quantified by EPA, the emission control cost is said to be about $10.9 billion per year, while the Hg-emission-cut-related benefit was determined to be no more than $6 million; this is a far cry from the “slam dunk” declaration from EPA, environmental and public health alarmists, and the press that mercury reduction benefits will be significant.
(c) The EPA proposal neglects key scientific knowledge and many peer-reviewed papers that suggest there is no straightforward connection between mercury (Hg) emissions from power plants, or other man-made sources, to the mercury level in fish. There is little doubt that levels of the biologically active form of mercury, methylmercury (MeHg), that are ultimately accumulating in fish tissue depend primarily upon environmental factors, such as sunlight and organic matter, pH, water temperature, and amounts of sulfate, bacteria, and zooplankton present in the ecosystem.
MeHg levels in fish do not depend simply on the amount of elemental Hg available for conversion. This is why a distinguished group of mercury science experts 6 concluded that a simple change in bacterial activity alone could “cause an increase in fish mercury concentrations, even as atmospheric deposition [from industrial mercury emission sources] decreases.” [Emphasis added]
(d) The EPA proposal fails specifically to recognize the fact that existing accurate measurements of atmospheric mercury concentrations worldwide (first published in 2003, 8 with an updated publication in 2011) 9 have long shown the systematic
decreases of atmospheric mercury in the periods 1990-1996 and then 1995–2009 are completely inconsistent with the expected increase in atmospheric mercury concentrations adopting the current inventories of anthropogenic mercury emissions.
Crucially, this has led the EPA, in the proposed NESHAP, to ignore the important role played by mercury emissions and recycling related to natural sources.
(e) The EPA proposal continues to incorrectly promote the flawed Faroe Islands’ children study as the EPA’s standard of proof for the harm that exposure to MeHg causes to children and women. It ignores the far different conclusions reached by superior epidemiological results from the Seychelles Island Children Development Study (SCDS). The SCDS study did not confirm any harmful effect on children due to MeHg exposure from eating a variety of ocean-caught fish at levels that are more representative for American public health. 10
In sharp contrast, the Faroe Island study population is well known to be exposed to not only MeHg but also other contaminants like polychlorinated biphenyls (PCBs) and lead. More importantly, the Faroe Island population got its MeHg dosage through consumption of highly contaminated pilot whale meats and blubbers, as admitted by Dr. Pal Weihe, the Chief Physician of the Department of Occupational and Public Health of the Faroese Hospital System.
Despite EPA’s claims, the agency’s proposed NESHAP rules actually document the scientific bias of the NRC’s 2000 report, Toxicological Effects of Methylmercury, in that EPA specifically did not consider the results from the Seychelles Children Study, which fail to confirm any adverse effect of MeHg exposure through consumption of ocean fish. The result is that EPA’s Reference Dose (RfD) for MeHg exposure can be shown to be excessively exaggerated by at least a factor of 10.
(f) The EPA proposal is demonstrably biased in failing to distinguish between prenatal and postnatal exposure to MeHg, and to note that the Faroe Island study concluded as early as 2006 that “postnatal methylmercury exposure had no discernible effect.”11
This reality is consistent with Seychelles SCDS analysis, which found “several associations between postnatal MeHg biomarkers and children’s developmental endpoints. However, as has been the case with prenatal MeHg exposure in the SCDS main cohort study, no consistent pattern of associations emerged to support a causal relationship.”12
(g) The EPA proposal gave outdated information for 1999-2000 and 2001-2002 (and based its discussion of risk) regarding the crucial public health endpoint for MeHg exposure risk of American women of childbearing age (16-49) and children (1-5) based on the Center for Disease Control and Prevention’s (CDC) National Health and Nutrition Examination Survey (NHANES). This WS report corrected EPA’s failure by showing the NHANES results for 2003-2004, 2005-2006 and 2007-2008.
The good news for American public health is that the high-end 95th percentile levels of blood mercury measured for both women and children have undergone systematic decreasing tendencies from 1999 through 2008, and the 2007-2008 values are significantly below the already exaggerated RfD “safe” level established by EPA. This reality raises the puzzling question: who or which group in particular are EPA’s proposed NESHAP rules supposed to protect, when available NHANES monitoring efforts clearly demonstrate that the overwhelming majority of Americans are already safe from any risk attributable to MeHg exposure through fish consumption?
(h) The EPA proposal failed in reviewing scientific literature, and understanding how to link MeHg exposure to cardiovascular health for adults. This report shows that the two major studies used by EPA (to imply causal link from MeHg to negative cardiovascular health) are flawed in design and the results are simply not applicable to fish-eating adults in America, or to U.S. public health in general.
(i) Authors of the EPA proposal failed to report and fully account for the most important role of dietary selenium’s protective effects against MeHg toxicity. The literature on the beneficial role of dietary selenium 12 (Se) against MeHg toxicity is widespread, 13 and it is well known that the binding affinity of Hg to Se is up to a million times higher than for sulfur – mercury’s second-best binding partner.
(j) The EPA proposal neglects several new scientific results and reports that will nullify any concerns about harmful health impacts from eating lake-caught fish. In particular, EPA neglected to consider an important study (funded by the EPA itself) showing that 97.5% of freshwater fish analyzed for a Western U.S. survey have sufficient selenium to “potentially protect them and their consumers against Hg toxicity.”
(k) The EPA proposal also appears to reflect an unscientific practice of citing nonpeer-reviewed private letters and conference talk presentations as key sources in reaching its major and crucial decision in issuing its NESHAP, whereas only peer-reviewed studies should form the basis for such an important rulemaking. 14
(l) The EPA proposal is designed to set the stage for creating a socio-political consensus for determining a dose-response relationship on MeHg affecting cardiovascular health 15 for adults, despite very weak factual epidemiological evidence, as documented in this report.
Additional research reveals that such a model will allow EPA to promote its claim that increasingly stringent mercury emission reductions from EGUs will result in very significant public health benefits,16 regardless of whether a causal basis for the asserted connection actually exists. 17
Historically, MeHg bioaccumulation and methylation occur as a result of factors other than levels of elemental Hg available, either from pre-existing mercury naturally found in the soil, water and air, or from much lower emissions from human activity.
The scientific literature to date strongly and overwhelmingly suggests that meaningful management of mercury is likely impossible, because even a total elimination of all industrial emissions, especially those from U.S. coal-fired power plants, will almost certainly not be able to affect trace, or even high, levels of MeHg that have been found in fish tissue over century-long time periods.
A more rational and informed framework for dealing with the relatively low risk of MeHg exposure through fish consumption is required. Thus far, it is clear that the EPA’s proposed NESHAP may actually be counter-productive to the protection of American public health.
1 The 946-page EPA’s NESHAP proposal is available here: Published in Federal Register on May 3, 2011; available here.
2 UNEP’s “The Global Atmospheric Mercury Assessment: Sources, Emissions and Transport” (2008; updated and corrected May 2009).
3 See EPA’s November 10 2009’s press release.
4 Wiedinmyer and Friedli (2007) Environmental Science & Technology, vol. 41, 8092-8098.
5 EPA’s “co-benefits” claim should not go unchallenged. It is not entirely clear on what the EPA NESHAP proposal is achieving for the ever-more stringent PM2.5 control since as the real-world data is showing a steady decreasing tendency for the PM2.5 air quality standard from 2000 through 2009, with means below the National Standard, as shown below: (source of the graph)
6 Mason et al. (2005) Environmental Science & Technology, vol. 39, A14-A22.
7 Slemr et al. (2003) Geophysical Research Letters, vol. 30, 2003GL016954.
8 Slemr et al. (2011) Atmospheric Chemistry and Physics, vol. 11, 4779-4787..
9 The mercury exposure levels in Seychelles are about 10 times those of U.S. women and they eat fish with
mercury similar to those of the U.S. commercial ocean fish.
10 Debes et al. (2006) Neurotoxicology and Teratology, vol. 28, 536-547.
11 Myers et al. (2009) Neurotoxicology, vol. 30, 338-349.
12 Soon notes that selenium, Se, is one of the other 83 toxic hazardous air pollutants considered in this EPA’s NESHAP proposed rules. This EPA proposal estimated that total Se emission from EGUs for 2010 is about 258 tons (p. 171-172 of EPA document or p. 25006 in Federal Register) and the meaning of this emission control needs to be confronted with the reality that marine biogenic emission of Se is estimated to be roughly 5000-8000 tons and total Se recycled through the atmosphere is about 13000 to 19000 tons (see 7 Wen and Carignan, 2007, Atmospheric Environment, vol. 41, 7151-7165). Although not within the scope of this report, I point out this relevant new paper by Jardine and Kidd (2011, Science of the Total Environment, vol. 409, 785-791) where the study could not find any relation between the concentration of Se in fish tissues and coal-fired power plant locations and emission outputs (see figure shown in this endnote):
“Our data showed no relationship between the proximity to the coal-fired power plant and Se concentrations in local biota. There was no relationship between Se concentrations and distance from the coal-fired power place for [blacknose] dace (r2 < 0.01, p=0.806, n=29), [brook] trout (r2 <0.01, p=0.910, n=25), water strider (r2 = 0.03, p=0.307, n=41; not shown) or predatory invertebrates (r2 < 0.01, p=0.977, n=14; not shown). This may be due to the very low amount of Se emitted from coal burning relative to Hg and S [sulfur], as concentrations of Se are approximately 2000 times lower than S in coal. This and other coal-fired power plants may also emit low levels of Se compared with that released from other point sources such as metal smelters. The Sudbury metal smelters have
historically been identified as being one of the world’s largest Se emission sources at approximately 2 tonnes per day, likely much larger than emitted from the power plant in the current study. … [M]any fishes had lower [Se] concentrations than their invertebrate prey and trophic transfer was higher at sites with low invertebrate Se concentrations. Variability in Se concentrations in fishes was explained more by site of capture than microhabitat use within the site, suggesting among-site differences in geological sources of Se. … Our studies suggest that, as predicted by kinetic models (Wang, 2002), trophic enrichment of Se is a rare phenomenon in these stream food webs. Furthermore, the concentrations of Se are not a concern for fish and wildlife supported by these systems, and are consistent with previous, low Se measurements on the blood of fish-eating common loons in the region. ” [emphasis added]
13 Ralston and Raymond (2010) Toxicology, vol. 278, 112-123.
14 Although this is not the focus of this report, I point out that:
(1) On pp. 272-273: although EPA claimed to base its proposed 91% Hg emission cuts on actual data, EPA specifically admitted (p. 273) that with the Active Carbon Injection (ACI) Control Technology, “EPA had no direct stack test results showing how effectively these ACI-equipped plants reduced their Hg.”
(2) On p.399: similar statements by EPA, acknowledging that they have no measured or proven data to achieve the 91% Hg emission cuts.
(3) On p. 440: EPA specifically cited a private (opinion) letter from one David Foerter, executive director of the Institute of Clean Air Companies to former Senator Carper in footnote #172 for its claim that wet and dry scrubbers could be installed within 3 years time.
(4) On pp. 445-446: EPA cited another non-peer-reviewed lowerPoint presentation (as footnote #173) by one Paul M. Sotkiewicz of PJM Interconnection, in support of its claim that Hg control could be online by “third quarter of 2014”. [WS noted on April 7, 2011: Scott Segal, a partner at Bracewell & Giuliani and president of the Electric Reliability Coordinating Council, also independently raised this point in a t.v. interview on March 28, 2011 available here Willie Soon is an independent scientist who for the past 10 years has studied the biogeochemical nature of mercury in our environment and its effects on human health.