Hydraulic fracturing or fracking, a drilling method that uses water, sand and chemicals to release natural gas from wells, should be studied for its health effects on people and food sources, said a top official at the U.S. Centers for Disease Control and Prevention.

The Environmental Protection Agency plans to study the impact of the drilling method on drinking water. Additional studies should examine whether wastewater from the wells can harm people or animals and vegetables they eat, said Christopher Portier, director of the CDC’s National Center for Environmental Health and the Agency for Toxic Substances and Disease Registry.

“We do not have enough information to say with certainty whether shale gas drilling poses a threat to public health,” he said in an e-mail sent by Vivi Abrams, a spokeswoman.

An increase in gas production using hydraulic fracturing, raised production of the fuel, reduced prices 32 percent last year and led to questions about the environmental effects on drinking water supplies. Further development of shale resources using fracking may add more than 1.6 million jobs by 2035, according to the American Petroleum Institute, the largest energy trade group in Washington.

Chemicals used in fracking should be monitored, Portier said, and drinking water wells should be tested before and after drilling. Studies should examine “all the ways people can be exposed” to fracking products, including through air, water, soil, plants and animals.

Portier wouldn’t say whether fracking should be stopped or more tightly regulated until studies are completed.

“Our role is to determine what the risks are, and it is up to the public to decide if they are OK with that risk,” he said.

To contact the reporter on this story: Alex Wayne in Washington at awayne3@bloomberg.net