PITTSBURGH -- The oil and gas industry is trying to ease environmental concerns by developing nontoxic fluids for the drilling process known as fracking, but it's not clear whether the new product will be widely embraced by drilling companies.Houston-based energy giant Halliburton Inc. has developed a product called CleanStim, which uses only food-industry ingredients. Other companies have developed nontoxic fluids as well."Halliburton is in the business to provide solutions to our customers," production manager Nicholas Gardiner said. "Those solutions have to include ways to reduce the safety or environmental concerns that the public might have."Environmental groups say they welcome the news but still have questions.The chemicals in fracking fluids aren't the only environmental concern, said George Jugovic, president of PennFuture. He said there is also concern about the large volumes of naturally occurring but exceptionally salty wastewater and air pollution.It's premature to say whether it will ever be feasible to have fluids for fracking that are totally nontoxic, said Scott Anderson, a senior adviser for the Environmental Defense Fund."But we are encouraged to some extent by recent industry efforts to at least reduce the toxicity," Anderson said.Fracking, or hydraulic fracturing, has made it possible to tap into energy reserves across the nation but has also raised concerns about pollution, since large volumes of water, along with sand and hazardous chemicals, are injected deep into the ground to free the oil and gas from rock.