Re: Niagara Transuranics and Hg mistake

[Steven Dapra <sjd@swcp.com>]

April 7



	John Jacobus wrote:  "Not to be a nucance, but I would still like to know

if mercury for coal burning contributes to mercury contamination in the

ocean/food chain.  If so, we need to stop burning coal and increase our use

of nuclear power."



	The easy answer is "yes," coal burning contributes to mercury

contamination in the ocean, and in the food chain.  There are some

intricacies though.



	The EPA has estimated that the total amount of mercury emitted from

coal-fired power plants in the US is 52 tons per year.  The EPRI estimates

47 tons per year.  This is about one-third of the EPA's estimated 158 tons

per year of man-made mercury emissions in the US.



	From the EPA's website:  "According to EPA's 1999 National Emissions

Inventory, coal-fired electric power plants are the largest source of

human-caused mercury air emissions in the U.S. Power plants account for

about 40% of total U.S. manmade mercury emissions. Other large sources are

industrial boilers (about 10% of U.S. mercury emissions), burning hazardous

waste (about 5%), and chlorine production (also about 5%). Burning

municipal waste and medical waste was once a large source of emissions but

today, in response to EPA and State regulations and reductions in mercury

use, these sources are much less important."  (Link:

<http://www.epa.gov/mercury/information1.htm>) 



	This says nothing about global emissions, and the EPA's current "Frequent

Questions" also say nothing about global emissions.  I have a set of EPA

FAQs about mercury that I printed out in December of 2000, and these FAQs

<do> inform the reader about global emissions.  The EPA's own question was

"How much does the U.S. contribute to worldwide mercury emissions?"

Answer:  "Although the amount of mercury the U.S. contributes globally is

small (about 3 percent), it still contributes more than it receives."  The

FAQ says more about US contributions, but note that the US is made into the

villain (we don't contribute much - about three percent -  but we "still

contribute more than (we) receive."  (The current FAQs were last updated on

3-31-04.  I won't address the convenient omission of the US's mere three

percent contribution.)



	Regardless of all that, it appears that EPA has estimated total worldwide

emissions of mercury at from 5000 to 5500 tons per year.  Of this, 2000

tons are estimated to come from man-made sources, 1000 tons from natural

sources, and 2000 tons from re-emissions.  Mercury emissions from US

coal-fired plants amount to about one percent of worldwide emissions.



	In 1998, the EPRI's Leonard Levin, Ph. D. had some germane observations on

mercury:



	"The linkage between these [man-made] sources [of mercury] and deposition

is poorly understood, even for very large sources of mercury.  This is

largely because the chemical state of the mercury leaving a source is

critical in determining how far the mercury will travel before it is

removed from the atmosphere.  Data on whether mercury from a particular

source is ionized or in its 'elemental' form are basically lacking for most

sources."



	"Direct measurements of mercury depositing to U.S. territory are still

sparse, and not representative yet of the entire nation."



	Levin said that potential changes in U.S. industrial emissions might leave

the overall source term "basically unchanged," and then said:



	"As indirect evidence of this, there are no data showing any overall

lowering of mercury levels in fish from remote lakes over the past 35

years, despite an 85% drop in U.S. industrial mercury use in that time."

The link to Levin's statement is :

<http://epw.senate.gov/105th/lev_10-1.htm>.  As of today this link was

working.



	For a large (22 page) "Toxicity summary for mercury" go to

<http://risk.lsd.ornl.gov/tox/profiles/mercury_f_V1.shtml>.  (Dale Boyce

also gave this link in his posting this evening.)



	For an informative paper on "Global Source Attribution for Mercury

Deposition in the United States," see Seigneur et al. (2004).  In

particular, see the Introduction (p. 555), and "Global Source Attribution,"

(pp. 564-568).  The above-mentioned Dr. Leonard Levin assisted in preparing

this paper.



	You can also see the editorial "Methylmercury Exposure and Neurotoxicity"

(Mahaffey 1998) in JAMA, discussing a mercury study in children on the

Seychelles Islands in the Indian Ocean.  A study of Faroe Island (North

Atlantic) children is being conducted and I have read some summaries of

these two studies, but the findings seem to be inconclusive with respect to

adverse human health effects.



	I have read some anti-mercury material, including a 1999 Environmental

Working Group report on US emissions (primarily from coal-fired plants),

but none of the 'antis' cite studies showing adverse health effects except

for large exposures; such as in Iraq (in 1972) and at Minamata Bay.  



	The National Academy Press has an online book ("Toxicological Effects of

Methylmercury"), and on page 325 the author(s) say that a study committee

developed estimates to "indicate that over 60,000 newborns annually might

be at risk for adverse neurodevelopmental effects from in utero exposure to

MeHg [methylmercury]."  This assertion is repeated on page 327 (with

slightly different wording), but on neither page do the author(s) give

citations to source material to support this estimate or to explain how it

was derived.



	To answer your question, John; yes, coal burning does contribute to

mercury contamination.  But:  apparently no one can prove or even show how

much of this mercury ends up in the food chain; and apparently no one can

prove or even show that the mercury in coal has had any adverse human

health effects.



Steven Dapra

sjd@swcp.com



REFERENCES	



Mahaffey K. JAMA.  280(737-738); Aug. 26, 1998.



Seigneur C., et al.  Environmental Science and Technology; 38(2):555-569;

2004.  (ES&T is published by the American Chemical Society.)









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