(CNN) The Department of Energy may have shipped dangerous radioactive waste into a landfill in Nevada for several years, Nevada Gov. Steve Sisolak announced Wednesday.

A statement from Sisolak said Energy Department officials told him on July 3 that the Nevada National Security Site may have received a total of nine shipments and 32 containers of "mixed low-level radioactive waste" from a facility in Tennessee from 2013 to 2018 that were supposed to be "low-level radioactive waste."

"It's not just an issue of regulation, it's an issue of health and safety," said Nevada Division of Environmental Protection Administrator Greg Lovato.

CNN has reached out to the Department of Energy for comment.

According to the Nevada National Security Site website, low-level waste generally includes materials such as rags, papers, filters, equipment, discarded protective clothing and construction debris.

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