Wednesday, September 05, 2012

Radon-222 Content In Natural Gas

Fracking Opponents and Proponents Weigh In

A debate is raging in the fracking area about the content of radioactive radon-222 in Marcellus Shale gas.  Opponents say it poses a threat to the health of residents of New York and proponents say the levels are below levels that would pose a threat to public health.  We present the data.  You decide.

Radon (chemical symbol Rn) is a naturally occurring radioactive gas found in soils, rock, and water throughout the U.S. It has numerous different isotopes, but radon-220, and -222 are the most common. Radon causes lung cancer, and is a threat to health because it tends to collect in homes, sometimes to very high concentrations. As a result, radon is the largest source of exposure to naturally occurring radiation. (EPA)

One of the primary studies cited was conducted by the U.S. Geological Survey, "Radon-222 Content of Natural Gas Samples from Upper and Middle Devonian Sandstone and Shale Reservoirs in Pennsylvania: Preliminary Data," and the abstract is below:
Samples of natural gas were collected as part of a study of formation water chemistry in oil and gas reservoirs in the Appalachian Basin. Nineteen samples (plus two duplicates) were collected from 11 wells producing gas from Upper Devonian sandstones and the Middle Devonian Marcellus Shale in Pennsylvania. The samples were collected from valves located between the wellhead and the gas-water separator. Analyses of the radon content of the gas indicated 222Rn (radon-222) activities ranging from 1 to 79 picocuries per liter (pCi/L) with an overall median of 37 pCi/L. The radon activities of the Upper Devonian sandstone samples overlap to a large degree with the activities of the Marcellus Shale samples.
Opponents cite a January 10, 2012 report by Marvin Resnikoff entitled, "Radon in Natural from Marcellus Shale," as their front line assault on fracking gas use in New York.  The executive summary states:
A significant public health hazard associated with drilling for natural gas in the Marcellus Shale formation must be seriously investigated by the New York State Department of Environmental Conservation (DEC). This hazard is from radioactive radon gas and the potential for large numbers of lung cancer among natural gas customers. This issue, which has been ignored in the DEC’s Draft Supplemental Environmental Impact Statement, must be addressed in a revised Impact Statement and before DEC issues any drilling permits.
Energy In Depth (EID) provides a rebuttal of the Resnikoff findings.  EID posts on their blog that the USGS seriously question Resnikoff's findings:
A recent report by Resnikoff (2012) has led to increased interest in possible human exposure to radon as a component of natural gas in household settings. The report, however, relied on theoretical calculations utilizing limited data from geologic analogs.
A decision was made to release our small and preliminary dataset because, to the authors’ knowledge, measurements of radon in natural gas at the wellhead have not previously been published for the Appalachian Basin.
EID follows with its own rebuttal of Resnikoff: 
Marvin Resnikoff...was wrong on radioactivity levels in the Marcellus Shale, wrong on his conversions radioactivity to radium readings and wrong in his assumptions regarding what this means for radon concentrations in the natural gas that goes into the pipeline.
The USGS study went on to note that the half-life for radon-222 is 3.8 days and after two half lives (7.6 days) the radon content of gas from the wells with the highest concentrations would only naturally decay to 19.8 pCi/L. It should be noted that the EPA recommends “that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L.

1 comment:

Anonymous said...

What everyone forgets in this issue -- other than serious researchers -- is that even if the radon in the natural gas reaching your home is 20 pCi/l, the radon is diluted and dispersed in your kitchen when it comes out of the burner on the stove. The stove is invariably vented and the radon concentration that you are actually breathing is many orders of magnitude less than the EPA's recommended action level.