Nobody has systemically tracked how many health complaints there are, whether the complaints are similar, whether they can be tied to any specific chemical exposure or any environmental cause. It makes it very difficult beyond an anecdotal answer to get a handle on how widespread a problem this might be."
Part of the problem, writes Lustgarten, is that "the drilling companies have complicated efforts to gather pollution data and to understand the root of health complaints."
"The Clean Air Act requires reporting of emissions so that the government can collect the [toxic emissions] data from facilities of a certain size," he says. "The oil and gas facilities often fall under that threshold and an exemption allows them not to be aggregated or counted together. Because these facilities are small, there is no obligation to report to federal authorities what pollutants might be emitted from those facilities ... which means there's no information to paint a bigger picture of what communities are dealing with."
In addition, he tells Davies that states and federal agencies do not currently track anecdotal reports from people living close to drilling sites. Without an accurate measure of possible pollutants or contaminants near drilling sites, or a comprehensive database of population-based health data, it's difficult for epidemiologists to establish any link between gas drilling and ill health, says Lustgarten.
"You have to establish that there is a pollutant to be exposed to, that there is a risk to being exposed to that pollutant and then finally that people were exposed to that pollutant," he says. "And to investigate [this] scientifically would require an enormous study with, for example, a control population of people who aren't exposed to any kind of drilling and then people that are and watching them over time, while measuring air pollutants in the air and people's bloodstreams [to] definitively conclude that the specific contaminants from a specific source are the same ones that are making people sick."