U.S. Sen. Mazie Hirono and four other Senate Democrats are calling for an investigation into the possible removal of references to climate change in scientific reports by Department of the Interior employees.

“If true, this situation casts doubt on the accuracy of the Secretary’s comments, and raises serious concerns with respect to how the Department is — or is not — applying its scientific integrity policies to publicly released scientific reports,” Hirono wrote in a letter to U.S. Department of Interior Deputy Inspector General Mary Kendall.

On March 13, Hirono had questioned Secretary of Interior Ryan Zinke about the department’s censorship of the words “climate change” in a pending National Park Service report on the impacts of sea level rise on coastal flooding. Zinke denied changing any of the report, saying not even a comma was changed.

The letter requests an investigation into any instances when Department of the Interior employees edited the report, as well as under who’s direction those edits were made and any other instances of interference with scientific reports or scientific communications. It also seeks answers to why the report’s release to the public, originally announced as late 2016, has been delayed.

Senators Catherine Cortez Masto (D-Nev.), Tammy Duckworth (D-Ill.), Bernie Sanders (I-Vt.), and Ron Wyden (D-Ore.) also signed the letter.

Hirono letter to Deputy Inspector General of U.S. Department of the Interior by Honolulu Star-Advertiser on Scribd