I am sure that worksafe laws in every state suggests that you have the legal right to refuse tasks that you believe are unsafe... just do not refuse any reasonable (safe) task.
then it is up to the government authority to make a decision, if you have some facts about the issue's actual safety, no inspector would rule against you.
I heard that the US Navy were 160kms offshore off Japan about 4 days ago and the instruments on their fleet measured Radioactive material above safe levels, they left the area as soon as it became apparent.
the company must provide a workplace that is as safe as practicable.