Baker Hughes' much-praised practice of fully disclosing the ingredients in its fracturing fluid faces an uncertain future now that Baker Hughes is poised to merge into larger rival Halliburton.

Environmental groups lauded Baker Hughes last month after it announced it would start providing complete lists of all the chemicals used in the liquid mixture it shoots underground to help fracture rock and stimulate oil and gas production.

But officials from both companies say that at this point, it's not certain whether the practice would continue if Baker Hughes has a new owner in Halliburton. The merger between the two is expected to close next year, pending approval by shareholders and regulators.

"So long as Halliburton adopts the same approach as Baker Hughes, there won't be an issue, but the question is: Will they? We don't know the answer," said Mark Brownstein, associate vice president at the Environmental Defense Fund.

Baker Hughes began posting fracturing chemical information online last month, and it will continue to do so until the Halliburton transaction closes, said Melanie Kania, a Baker Hughes spokeswoman.

"We're going to continue with the commitment we made earlier this year," Kania said.

Kania declined to speculate on whether those disclosures would continue under Halliburton.

"At this point, it is premature to outline potential integration plans," Halliburton spokeswoman Emily Mir said when asked whether the company would continue Baker Hughes' disclosure practices.

Baker Hughes said last month that it had completed a six-month process of working with suppliers to reveal the details of the chemicals it uses in hydraulic fracturing. As a result, Baker Hughes is the first major oil field service company to offer up that type of data.

Advocates say there are environmental and health concerns associated with hydraulic fracturing and argue disclosures are necessary to help monitor communities for contamination. They also say emergency responders need reliable access to chemical information in case of fires or spills at drill sites.

Baker Hughes uploads the data to FracFocus, a website several state regulators including those in Texas use as a repository of fracturing fluid data.

"The policy we are implementing today is consistent with our belief that we are partners in solving industry challenges, and that we have a responsibility to provide the public with the information they want and deserve," Baker Hughes' chief strategy officer, Derek Mathieson, said in a statement last month when the disclosures were announced.

The move made Baker Hughes an outlier in the industry as it moved away from the use of "trade secrets" exemptions that some companies invoke to avoid fully reporting data to the website. A March report by the U.S. Department of Energy found that 84 percent of the wells listed on the FracFocus website used a trade secret exemption for at least one chemical.

Some energy companies had argued that disclosing the ingredients ran the risk of revealing information that could hurt their competitive position. But Baker Hughes said it was able to avoid that by revealing the names of chemicals used in its fluids without detailing their exact formulas or ratios - essentially offering up ingredients but not the recipe.

The decision garnered high marks from the Department of Energy as well as several environmental organizations. "What Baker Hughes did was basically put all the chemicals out there for the public to know," Brownstein said. "That's something that identified them in the industry as a leader."

Environmental advocates say they hope Halliburton will continue the practice.

But Amy Mall, a senior policy analyst at the Natural Resources Defense Council, pointed to Halliburton's recent lobbying on proposed federal chemical disclosure rules as cause for concern. Earlier this month, according to U.S. General Service Administration records, Halliburton's lobbyists met with federal officials to discuss proposed Bureau of Land Management rules that would require disclosure of chemicals used in hydraulic fracturing on public land.

In handouts to federal officials, Halliburton said disclosures are unnecessary because hydraulic fracturing doesn't pose a risk to water.