The GOP chairman of the House Science, Space and Technology Committee accused the Environmental Protection Agency of flouting a subpoena he issued requesting data from various public health studies.

Chairman Lamar Smith (R-Texas) and the EPA are battling over whether the environmental regulator has the ability to give the panel information used in studies that the agency drew upon to craft some of its regulations.

Smith and the panel’s Republicans want to make that information available to the public and other researchers. They say it would shed light on how the EPA designs regulations that industry and conservatives say damage the economy.

“EPA is using the subpoenaed data to support regulations that could cost the American people trillions of dollars. Yet EPA has refused to make the data available to Congress or the American people. Regulations based on secret data have no place in a democracy,” Smith wrote in a letter to EPA Administrator Gina McCarthy on Tuesday.