The Labor Department’s rulemaking process needs a broader review, the head of the DOL’s Office of the Inspector General said in a letter to congressional Democrats.

DOL Inspector General Scott Dahl also stated in the letter that the office is reviewing the integrity of the Occupational Safety and Health Administration’s rulemaking process, and is looking into the DOL’s controversial proposal to allow 16- and 17-year-olds who work in nursing homes or hospitals to operate machines that lift patients from beds, without supervision .

Dahl is already in the midst of an audit into the DOL’s handling of a Wage and...