Most people on earth already have a low level of mercury in their bodies, which continues to accumulate over time. The challenge, therefore, is to prevent and control additional exposure to avoid mercury poisoning. For example, because big fish store methylmercury in their bodies, you should try to limit how much shark, swordfish, tilefish, and king mackerel you eat. You need to be very careful when you handle and dispose of anything with mercury, including batteries, fluorescent lights, and some medical equipment. Never vacuum up spilled mercury, steer clear of cosmetics that contain mercury, and make sure your workplace is ventilated correctly if mercury is used in manufacturing.