Most compounds containing mercury are poisonous.
Methylmercury is an organic form of mercury that has been used to preserve seed grain. Methylmercury can also be produced from metallic mercury or mercury compounds in bodies of water by the action of bacteria. Outbreaks of methylmercury poisoning have occurred following ingestion of seedgrain or meat from animals fed seedgrain and from fish in waters contaminated with methylmercury such as Minamata Bay in Japan. The fetus and young infants are very sensitive to methylmercury's effects. Many of the CNS effects are similar to those seen in cerebral palsy , and methylmercury is thought to cause a form of cerebral palsy.