The Environmental Protection Agency released a progress report on its research into potential impacts of fracking on drinking water.
The update doesn't come to any conclusions and the final report won't be released until the New Year.
The EPA says information on fracking chemicals has been collected from nine companies and more than 24,000 wells.
They took samples from five locations in Colorado, North Dakota, Pennsylvania and Texas.
Lab studies are being done on drilling wastewater.
Fracking involves shooting high powered water and chemicals into underground rocks to retrieve oil and natural gas.
The EPA says it is working with scientists, the industry and environmental groups to examine any possible impacts.
The industry and many states say the process is safe when done properly but critics dispute that.