I filed a Freedom of Information Act request with OSHA looking for complaints against Apple. OSHA referred my request to various regional agencies. The office in Missouri which covers a large swath of the Midwest sent back two large PDF documents of redacted information that included not only OSHA investigations, but fines that have been paid by Apple for violations circa 2010-2015.
Part one is 66 pages long (Archive.org)
Part two is 91 pages long (Archive.org)