The Environmental Protection Agency (EPA) has approved for use in government road construction projects a substance that has been regulated due to radioactivity. 

Phosphogypsum, a waste product that comes from the production of phosphate fertilizer, will be allowed to be used in government road construction, the EPA announced Wednesday.

The material is currently kept in large “stacks” that are located in 13 states, primarily in the Southeast. That is also where most of the phosphogypsum roads would be built, as the group that requested the approval told EPA that it would be “uneconomical” to transport it farther than 200 miles from the stacks, according to the agency.