Under a new law, doctors in Pennsylvania can access information about chemicals used in natural gas extraction—but they won't be able to share it with their patients. A provision buried in a law passed last month is drawing scrutiny from the public health and environmental community, who argue that it will "gag" doctors who want to raise concerns related to oil and gas extraction with the people they treat and the general public.

Pennsylvania is at the forefront in the debate over "fracking," the process by which a high-pressure mixture of chemicals, sand, and water are blasted into rock to tap into the gas. Recent discoveries of great reserves in the Marcellus Shale region of the state prompted a rush to development, as have advancements in fracking technologies. But with those changes have come a number of concerns from citizens about potential environmental and health impacts from natural gas drilling.