Methylmercury is a toxic compound formed when mercury, a heavy metal, is converted by microorganisms in aquatic environments. It can accumulate in fish and other organisms, posing health risks to those who consume them. Methylmercury is particularly harmful because it can easily enter the human body and affect the nervous system. Exposure to methylmercury can lead to serious health issues, including cognitive impairments and developmental delays, especially in fetuses and young children. Monitoring and regulating mercury emissions from sources like coal-fired power plants and industrial processes are essential to reduce the risks associated with methylmercury contamination in the environment.