The Philadelphia Inquirer has an editorial on the “Risks of Hydrofracking.” They point out some important factors, including the fact that drillers are not being forthcoming about what they are injecting into the subsurface. But this information may be easier to get than people often allow.
As I’ve noted previously, if these compounds are discharged to surface waters (and they often are, because one step in hydrofracking is pumping out what gets pumped in, and what gets pumped out is often discharged), then they cannot be kept confidential (by virtue of being a trade secret, for example).
One problem is that claims of confidentiality here, once made by a driller’s attorneys, must at this point be challenged (usually using legal machinations, but not always) in order to free up the information. There are subtleties to this matter, one of which is that there can be cross referencing between state and federal regulations that one has to … forgive the expression… drill down into and understand.