HOPE YEN, Associated Press

WASHINGTON (AP) — Democrats on a congressional oversight panel are stepping up their investigation into how well states are regulating the disposal of oil and gas waste, citing public concern about the potential environmental and health risks of hydraulic fracturing.

Rep. Matt Cartwright of Pennsylvania is the lead Democrat on a House oversight subcommittee. He is pressing agencies in Pennsylvania, Ohio and West Virginia for answers on their level of enforcement and inspections. Republicans on the panel haven’t taken a position on the probe.

Of particular concern is making sure waterways are not contaminated by waste from fracking, which uses millions of gallons of high-pressure water mixed with sand and chemicals to break apart rocks rich in oil and gas.

Cartwright also wants to know how health complaints from local residents are handled.