PITTSBURGH — A major supplier to the oil and gas industry says it will begin disclosing 100 percent of the chemicals used in hydraulic fracturing fluid, with no exemptions for trade secrets. The move by Baker Hughes of Houston is a shift for a major firm; it’s unclear if others will follow suit.

The oil and gas industry has said the chemicals used are disclosed at tens of thousands of wells, but environmental and health groups and government regulators say a loophole that allows companies to hide chemical “trade secrets” has been a major problem.

A statement on the Baker Hughes website said the company believes it’s possible to disclose 100 percent “of the chemical ingredients we use in hydraulic fracturing fluids without compromising our formulations,” to increase public trust.

“This is really good news. It’s a step in the right direction,” said Dr. Bernard Goldstein, the former dean of the University of Pittsburgh Graduate School of Public Health. “One hopes that the entire industry goes along with it.”

But Goldstein noted one “major hedge” in the Baker Hughes position, because the company said it will provide complete lists of the products and chemical ingredients used in frack fluids “where accepted by our customers and relevant governmental authorities.”

Still, Goldstein said the Baker Hughes language sets a new standard for transparency and “clearly distinguishes them from Halliburton,” another major industry supplier.

A boom in drilling has led to tens of thousands of new wells being drilled using the fracking process. A mix of water, sand and chemicals is forced into deep underground formations to break rock apart and free oil and gas. That’s led to major economic benefits but also fears the chemicals used could spread to water supplies.