Dispersal of mercury into the air has risen substantially since the industrial revolution, leading to increased mercury deposits in water and soil. Once there, it gets transformed by bacteria into methylmercury, a highly toxic form of the naturally-occurring heavy metal that can affect neurological and immune systems. Stored in the tissues of wildlife and humans, methylmercury concentrations are magnified with each step up the food chain. The mercury levels of a large predator fish such as trout, for example, may be more than one million times that of ambient water, potentially causing serious health consequences for human and wildlife consumers.