Researchers at Harvard released a new study Tuesday showing elevated radiation levels at fracking sites, citing the concerning levels could pose health risks to residents in the adjacent area.

The study was published in the journal Nature and details how the controversial hydraulic fracturing drilling sites are registering radiation levels above normal background levels, Reuters reported.

Sites within 12 miles downwind of 100 fracking wells were found to have radiation levels that are about 7 percent above normal background levels, according to the study.

Harvard researchers analyzed thousands of the U.S. Environmental Protection Agency’s radiation monitor readings nationwide from 2011 to 2017 for its data.

The study added that readings could ascend much higher in areas closer to drilling sites or locations with higher concentrations of fracking wells.

“The increases are not extremely dangerous, but could raise certain health risks to people living nearby,” said the study’s lead author, Petros