Gov. Rick Perry has signed a bill requiring drillers to publicly disclose the chemicals they use when extracting oil and gas from dense rock formations, the first state to pass such a law.
Several other state agencies have passed regulations forcing some disclosure, but none have made it a law. Texas' law will force drillers to post the chemicals and the amounts used beginning in July 2012.
The issue has taken on national importance as hydraulic fracturing, or fracking, is used in more states to extract once out-of-reach hydrocarbons from impermeable shale formations. Drillers pump chemical-laced water into the ground at high pressure to crack the rock.
Environmental groups worry the chemicals could taint aquifers and water supplies. The industry says the process is safe.