An unidentified chemical used in fracking in the United States has triggered concern after it emerged it can cause kidney and liver damage.
A subsidiary of Nabors Industries Ltd pumped a mixture of chemicals identified only as "EXP-F0173-11" into half a dozen oil wells in rural Karnes County, Texas, in July.
One ingredient, a solvent, in the blend of chemicals can cause kidney and liver damage, according to information about the product that Michigan state regulators have on file.
A year-old Texas law that requires drillers to disclose chemicals they pump underground during fracking, was powerless to compel transparency for EXP-F0173-11. The solvent and several other ingredients in the product are considered a trade secret by Superior Well Services, a Nabors subsidiary, meaning they are exempt from disclosure.
Drilling companies in Texas, the biggest oil and natural gas producing state, claimed similar exemptions about 19,000 times in the year up to August, according to their chemical-disclosure reports.
Nationwide, companies withheld information on one in five chemicals they used in fracking, a separate examination of a broader database shows.
Trade-secret exemptions block information on more than five ingredients for every well in Texas, undermining the statute's purpose of informing people about chemicals that are transported through their communities and injected thousands of feet beneath their homes and farms, said Lon Burnam, a Democratic state representative and a co-author of the law.
A spokesman for Nabors declined to comment.
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