Fracking entails cracking layers of earth with pressurized, chemical-laden liquid to access stores of oil and gas thousands of feet underground. Many of the chemicals used in that liquid, like benzene and formaldehyde, are carcinogenic, and the extraction itself can stir up radium and other heavy metals in the shale’s subsurface, creating radioactive waste that can contaminate watersheds.

The companies that drill in the region and officials who support the industry have long insisted that fracking is safe and well-regulated. But many residents, who have seen unfamiliar sicknesses invade their community over the past 20 years, now feel misled.

Some of the health risks associated with fracking, such as asthma, pre-term births and heart problems, have been established for years. However, cancer is both rare and slow to progress, which means that it can take many years to produce a meaningful study connecting it to relatively novel environmental hazards, like fracking.

But research linking proximity to unconventional wells and developing certain types of cancer is gradually emerging.