The so-called Halliburton Loophole, named after the oil and gas services company once headed by former Vice President Dick Cheney, means that the industry can use fracking fluid containing chemicals linked to negative health effects including kidney and liver disease, fertility impairment, and reduced sperm counts without being subject to regulation under the act.

While environmentalists and public-health campaigners have long called for closing the loophole, they haven’t known how many of the regulated chemicals are used by the industry, how often the industry reports their use in its fracking disclosures, what quantities of the chemicals are used, and how often the industry chooses not to identify its chemicals on the grounds that they are proprietary.

Now, some of that data is publicly available in a study by researchers at Northeastern University and three other colleges. The paper, published in its final form in February, reports that the industry uses 28 chemicals regulated under the Safe Drinking Water Act and discloses them in up to 73 percent of its reports of fracking activities to FracFocus, an industry-sponsored database.

Between 2014 and 2021, the industry used 282 million pounds of the regulated chemicals, a number dwarfed by the 7.2 billion pounds of chemicals that were reported but not identified on the grounds that they are proprietary or trade secrets, the paper said.