Obfuscation Does Not Provide Comfort

There is no basis for the conclusion by Fryzek et al that their study “Childhood Cancer Incidence in Pennsylvania Counties in Relation to Living in Counties With Hydraulic Fracturing Sites” offers “comfort concerning health effects of HF on childhood cancers.”1 Its major flaws are that it seriously misrepresents the time line of the issue of concern, that of the development of hydraulic fracturing (HF) of horizontal wells for tightly bound shale gas in Pennsylvania; it does not include the appropriate epidemiological consideration of the lag period for carcinogenesis before 2009, the last year of their childhood cancer data; and it does not take into account the additional time at risk of exposure as a result of above-ground disposal of flowback fluids. Fryzek et al open their article with the usual industry claim that HF has been in use for 60 years. This is true, but generally immaterial to current concerns. The drilling industry justifiably points with pride to their new technology that now permits extraction of tightly bound shale gas long known to be present deep underground but previously unobtainable. These evolving HF practices use upward of 5 million gallons of water, however, rather than perhaps 50,000; have correspondingly much higher pressures; go beyond the vertical to bend the well to horizontally enter a shale layer a mile or more underground; blow holes into the shale layer to remove tightly bound gas; hydraulically fracture up to a dozen different wells from the same well pad sequentially rather than just a single well; use a changing suite of HF chemicals to extract the tightly bound gas; and have moved into geological areas with different naturally occurring and potentially toxic hydrocarbons, brine components, minerals, mineraloids, and radionuclides in the millions of gallons of flowback fluid from each site. Furthermore, this unconventional gas drilling (UGD) is now occurring in geographical areas in Pennsylvania with higher population densities and correspondingly higher overall population risks.2 It is this rapid growth of UGD that has in a few short years led to documented public concerns.3–5 Fryzek et al provide a figure and a table showing close to 30,000 wells drilled since 1998. They do not specify the number that were hydraulically fractured, although they show that only 2.5% are reported as being horizontal wells that typify UGD. We do not disagree about the total numbers of horizontal wells drilled in Pennsylvania between 1998 and 2009. We even find almost twice their amount in the Pennsylvania Department of Environmental Protection database. But this same database also demonstrates the crucial point that these were drilled almost totally in the last few years of their cancer data.6 In 2005, there were only eight drilled wells of this type in the entire Commonwealth of Pennsylvania. Since then, 36 were listed in 2006, 115 in 2007, 335 in 2008, 816 in 2009, 1598 in 2010, and 1963 in 2011.6 Contributing to Pennsylvanians’ concerns is that future UGD development is likely to be much more intense, with perhaps as many as 5000 new wells annually for 20 years. The period of time of UGD is crucial because of the need to epidemiologically take into account the lag period between the exposure to a carcinogen and the eventual development of a clinically observable cancer. Even for leukemia, which has a relatively short lag period for a cancer, the data from the atom bomb studies in Japan and from a study of infants receiving thymic irradiation suggest that a 4-year lag period before an appreciable increase in risk can be observed and as many as 15 years before all of the cases accumulate.7,8 Using a highly conservative 4-year lag period would mean that a cancer database ending in 2009 could only reflect the relatively few UGD wells from 2005 or before. Furthermore, any effect in 2009 would be highly diluted by their apparent use of perhaps a decade of cancer data in each county to typify the “after drilling” period. In addition, Pennsylvania's geology, in contrast to the West, generally precludes rapid disposal of flowback fluid in deep underground injection wells. The necessity of disposing of these fluids on the surface prolongs the period at risk for human exposure and further emphasizes the lack of temporal relevance of the authors’ approach. In keeping with the relative novelty of UGD drilling and its much higher volumes, disposal of flowback fluid in Pennsylvania did not become a significant issue until 2011, when a moratorium needed to be declared against the use of publicly owned treatment works for disposal of the high volume of potentially toxic flowback fluid.9 With our colleagues, we recently published findings that those who believe their health has been affected by UGD report stressors related to trust, responsiveness, and transparency at a higher rate than they do for stressors related to physical issues such as noise and odors.5 A not totally unreasonable response by the natural gas industry has been that fear mongering by UGD opponents has contributed to this stress. Nevertheless, in the case of the Fryzek et al study, what the public will hear about UGD and childhood cancer—likely for the first time—is controversy engendered by industry's funding of a study that obfuscates the issue and does not legitimately address the public's health concerns about the explosive growth of UGD in their backyards. Bernard D. Goldstein, MD Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pa Samantha Malone, MPH, CPH Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pa

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