In this scenario, I wouldn't say anything to my supervisor. But keeping in mind the sensitive nature of the work and the importance of safety measures that an employee should take, I would get a trainer to give training to all employees. In this way, new employees will learn the safety measures and the current employees will have a refresher course.
In this way, the new employee will learn the measures properly and the ones who don't give importance to safety measures will also learn the importance of taking precautionary measures.