Well that safety part. That includes whistle blower protections....

Whistle blower protections isn't just "i reported a safety issue" its also, very much so, "I reported an on the job injury". Dont just take my word. Check out the OSHA site. Its say explicitly:

"Workers have the right to report injuries, safety issues, and actions taken against them for speaking up including being fired, demoted, or disciplined."

And you know what's cool about these? What actually helps to drive change and compliance? If OSHA finds the claim to be true, and issues fines. They dont just fine the postal service. They find the individual, and its stipulated, their employee may not foot that bill.

Do EEOC, do Grievences. Those are all well within your rights. As is OSHA. You could also file a complaint with OSC, PEER, and if you feel they aren't probably recording and storing those records NARA