Effects of chronic occupational exposure to mercury, such as that commonly experienced by affected hatters, include mental confusion, emotional disturbances, and muscular weakness.[9] Severe neurological damage and kidney damage can also occur.[2] Neurological effects include Korsakoff's dementia and erethism (the set of neurological symptoms characteristically associated with mercury poisoning). Signs and symptoms can include red fingers, red toes, red cheeks, sweating, loss of hearing, bleeding from the ears and mouth, loss of appendages such as teeth, hair, and nails, lack of coordination, poor memory, shyness, insomnia, nervousness, tremors, and dizziness.[10] A survey of exposed U.S. hatters revealed predominantly neurological symptomatology, including intention tremor.[3] After chronic exposure to the mercury vapours, hatters tended to develop characteristic psychological traits, such as pathological shyness and marked irritability (box).[11] Such manifestations among hatters prompted several popular names for erethism, including "mad hatter disease",[9] "mad hatter syndrome",[12][13] "hatter's shakes" and "Danbury shakes".