That said, I don't think this story is very objective in that it unduly pushes the buttons of people who are chemical-phobic and that makes matters worse.
Here, ethylene glycol (aka MEG—mono ethylene glycol) is held up as a bogeyman without a satisfactorily explanation of why.
When or if MEG gets into the water table how much damage would it do? How much would a person likely consume in say the course of a year and how dangerous would it be? I can't answer that directly as I simply don't have the leakage figures so let's look at MEG's known dangers.
MEG is antifreeze that you put in your car engine and it is dangerous if consumed, and it doesn't take much to kill you about 50 to 100ml (a wineglass full if it's concentrated — in antifreeze it's quite diluted). It's also sweet and to deter kids from drinking it, it has Bitrex/denatonium added to make it extremely bitter.
OK, it's nasty stuff but what happens when you consume it? Well, it breaks down into oxalic acid and that's what's dangerous about it as oxalic acid is poisonous. But how much so? It just so happens that oxalic acid ocurrs naturally in the leaves of many green vegetables such as spinich, its concentrations are so high in rhubarb leaves that we're told only to eat the stems.
The point is that trace amounts of MEG won't do us harm because we're used to normally consuming somewhat more than just trace amounts of oxalic acid in our food.
A much greater danger to health are the aromatic hydrocarbons such as benzene which is definitely toxic and carcinogenic but you'll notice it doesn't head the list in this article because much less of it is released during fracking. But small amounts aren't as noteworthy as the large amount of MEG released even though it likely poses a much greater health risk over the long run.
This is why many articles of this type are both misleading and harmful. They not only distort the facts but they also give the frackers and their ilk ammunition to dismiss reports of their unacceptable activities as being inaccurate and or groundless.