The Environmental Protection Agency has placed roughly 140 employees on administrative leave days after they signed a public letter expressing concern about the treatment of federal employees and the Trump administration’s regulations on climate and public health.

More than 170 EPA employees put their names to the document, with about 100 more signing anonymously out of fear of retaliation, according to Jeremy Berg, a former editor-in-chief of Science magazine who is not an EPA employee but was among non-EPA scientists or academics to also sign. The latter figure includes 20 Nobel laureates.