Fracking

With drilling and fracking, the ingredients that make up the chemicals used to obtain oil and gas are legally allowed to be kept confidential.

Cause and effect can be difficult to prove, but here are a series of studies showing the potential connection between fracking and health risks.

The agency approved chemicals that carry risks including tumors and poisoning of the lungs.

Trump has promised to lift environmental restrictions on the energy sector.

The U.S. Environmental Protection Agency today issued a final report on the connection between hydraulic fracturing and contamination in drinking water. After stressing in June 2015 that there was no "widespread, systematic impact" on water, the agency now is emphasizing that fracking can affect drinking water under some circumstances.

Early versions highlighted contaminated drinking water and vulnerabilities from fracking. The final version turned out differently: Fracking had not "led to widespread, systemic impacts." Oil and gas cheered the findings.

The study concluded hydraulic fracturing isn't a danger to drinking water. Scientists say that's unproven.

Even at prices half what they once were, U.S. oil producers can make a profit