Tennessee for years has had a few lightly regulated natural gas wells in several north Tennessee counties. But with the rise of new techniques for hydraulic fracturing, or “fracking,” of deep shale deposits to release natural gas, those counties and others in northwest and southeast Tennessee — including Hamilton County — are now expected to become players in the national shale fracking industry. That may enrich the gas industry, but under the state’s lamentably lax environmental laws, fracking is likely to threaten public water supplies with toxic pollution, and run the risk of air contaminated by radon, methane and other potent toxins.