AUSTIN, TEXAS — As the controversial oil and gas drilling practice known as hydraulic fracturing continues to spread, governments around the world are grappling with how to regulate it. What should happen to the waste after the process, called fracking, ends? What taxes should oil and natural gas companies pay? What about earthquakes and air pollution?

One regulatory trend is becoming well-established: requirements that drilling companies disclose information about the chemicals used in fracking. The process involves shooting a mixture of water, sand and chemicals down a well to extract oil or gas deposited in shale rock. The chemicals are used for functions like reducing friction or killing bacteria. But the particulars of the disclosure requirements can differ significantly, and environmentalists are urging that they be broadened.

U.S. states that have enacted fracking disclosure legislation or rules include Arkansas, Colorado, Montana, Oklahoma, Pennsylvania, Texas and Wyoming. Ohio’s legislature approved disclosure rules last week that the governor is expected to sign into law. California is considering disclosure legislation, and the U.S. Interior Department, a repository of public lands, has also proposed disclosure rules .

In a report published this week, the International Energy Agency urged policy makers to adopt “full, mandatory disclosure of fracturing fluid additives and volumes,” to avoid sowing mistrust about fracking activities.