Organomercury compound consisting of a single mercury atom and two methyl groups [(CH₃)₂Hg], highly volatile and not persistent in the environment. As an organic mercury compound, it may form when mercury combines with carbon covalently (shares electrons forming a strong bond). Dimethylmercury is poisonous to the nervous system (a neurotoxin), it readily crosses the blood-brain barrier and causes a lack of coordination, sensory disturbance and changes in mental state. Dimethylmercury inhibits several stages of neurotransmission in the brain.