I live in the area of the most concentrated shale gas fracking in N. America and maybe the world. Sure, there have been pollution concerns, but the world is hardly ending - although it may seem that way for a lot of young people recently laid off from their natural gas fracking jobs down here in the rust belt. Before shale gas development, we were facing skyrocketing natural gas prices, the prospect of shortages, and many poor people could not afford to heat their homes. Makeshift heating arrangements caused many house fires and CO poisonings that killed a lot of poor people. All of the chemical hazards Ms. Burger lists could be eliminated with appropriate regulation. I really wish activists would stop with the silicosis and fracking thing, it makes them look stupid - any construction job, concrete or asphalt plant, quarry, or even daily walks on a beach on a breezy day present greater silicosis risks.
Do you know that the safety record, in terms of injury, occupational disease and fatality rate, is better for nuclear power than any other way of generating electricity - and it is virtually CO2 free too.
And GMOs by themselves are not harmful (though, in many cases very useful either) - their harm from is their usage to subjugate farming and food supply to a the system of "intellectual property" driven monopoly-capitalism. Publicly-developed, open-source GMO's used in different ways that could be beneficial (for example GMO technology that is not deliberately integrated with ever greater amounts of herbicide and pesticide use), and increase the viability of small farming.
Sanders is going to open himself to some pretty major attacks if he keeps the uncompromising "ban fracking" position. All the Republican will have to do is point out that Bernie wants you to face a $400/month heating bill (or maybe no heat at all) every winter and $8.00/gallon gasoline and that will be it for his prospects. Better that he promote alternatives to fossil fuels that will make fossil fuels and fracking redundant.