On the subject of microfracking chemicals, my father forwarded this link to me last night. I was looking through the list, and X-Cide 207 caught my eye - it's an industrial microbicide and fungicide, and is pretty nasty. It's explicitly labeled for fracking, and most of the rest of the chemicals look like similar biocides, industrial solvents, surfactants, and the like. Hrm, also Bio Clear 1000 and its relatives, which are also nasty microbicides - "slimacide", "algaecide", etc. Various caustic and acidic agents....
The nasty stuff looks like it is used to keep algaeal blooms from forming in the fracking circulatory system.
For the nasty stuff, it depends on concentrations, I suppose. This sort of stuff will be present in industrial brownfields. But as the article points out, these are all essentially trace substances in a slurry whose vast bulk is composed of the pure drinking-class water the Marcellus operators are extracting out of my industrial park's pumps. The list includes a number of rather dubious-looking environmentally-sensitive replacements for dirtier compounds. I say "dubious" because these sorts of substitutions tend to be less effective than the old poisons.
Eh, it's possible that somewhere down the line some of this stuff could get out into the general water table. But keep in mind that the old mines are volcanoes of nastier stuff all over this state's minefield regions, and all of them were cut right into the water-table, open sieves of heavy metal seepage. Even the worst case isn't going to be anything like the old mercury poisonings of the "golden age" of industrial mining operations. Heck, there are flooded, abandoned quarries all through this region with crystalline-clear water the color of nothing in nature - crystal-clear because nothing can live in the waters. I've been told that if you go swimming in some of them, you're going to get skin burns.