Mercury compounds are chemical substances that contain the element mercury. These compounds can be found in various forms, such as mercury(II) chloride and methylmercury. They are used in different applications, including batteries, thermometers, and some medical devices. However, many mercury compounds are toxic and can pose serious health risks to humans and the environment. The toxicity of mercury compounds arises from their ability to accumulate in living organisms, leading to harmful effects. For example, methylmercury can build up in fish, making them dangerous to eat. Because of these risks, it is essential to handle mercury compounds with care and to seek safer alternatives whenever possible.