I don't practice health law, but it would seem that the rules that apply would be those of the jurisdiction where the ship if registered. If there are a number of ships to which you may be assigned, you should check the rules and regs of each country.
It is also possible that the regs of every country where the shiip docks, may apply.
I would suggest that you contact an attorney who specializes in health law or possibly labor law.
I am an attorney admitted solely in NY. None of the answers I submit on this forum constitutes legal advice, even to questioners in NY, and no attorney-client relationship is hereby created.