NEW YORK (Reuters) - A Democratic congressman is asking the U.S. Interior Department to explain what happened to $400,000 officials there said they were withholding from a study about the health impacts of coal mining, according to a letter to the agency from the congressman, Raul Grijalva, released to the public on Tuesday.

In his letter, the Arizona representative said time had already run out for the department to spend the money, which it received during the 2016 fiscal year as a grant from the National Academies of Sciences, Engineering and Medicine and was obligated to spend within two years.

Grijalva said it appeared the department had decided not to spend it on the coal mining study “because of fears that it would conclusively show that mountaintop removal coal mining is a serious threat to the health of people living in Appalachia.”

In a statement emailed to Reuters, Heather Swift, an Interior Department spokeswoman, said agency began reviewing all of its grants and partnerships worth more than $100,000, “in order to ensure the department is using tax dollars in a way that advances the department’s mission and fulfills the roles mandated by Congress.” She said the grant for the study was put on hold as part of the review.

President Donald Trump has directed members of his cabinet, including Interior Secretary Ryan Zinke, as well as Environmental Protection Agency Administrator Scott Pruitt and Energy Secretary Rick Perry, to take a friendly approach to the coal industry in their departments’ policies. Last week, Pruitt announced the EPA was formally seeking to withdraw from a pollution-reduction plan devised under former President Barack Obama and declared an end to what he called the “war on coal.”

Zinke has sought to make more U.S. public lands managed by the Interior Department available for mining and drilling.

In his letter, Grijalva, who is the highest-ranking Democrat on the Republican-controlled U.S. House Natural Resources Committee, said he wanted “a detailed explanation” of why the money was spent elsewhere or, if it was not, why the department let the grant expire.