Minamata disease resulted from their eating fish contaminated with mercury industrial waste. The disease is characterized by peripheral sensory loss, tremors, dysarthria, ataxia, and both hearing and visual loss.
Even the unborn child is at risk from Minamata disease. Methyl mercury readily crosses the placenta from mother to fetus and is teratogenic, particularly to the developing brain. Children born with Minamata disease can have growth deficiency, microcephaly (an abnormally small head), severe mental retardation and be deaf and blind.
Minamata disease has not been confined to Minamata where the source of the mercury was primarily from eating fish caught in the contaminated Bay. Other sources of maternal exposure to methyl mercury have included flour made from seed grain treated with methyl mercury (which affected at least 6,500 people in Iraq) and meat from animals raised on mercury-tainted grain (in New Mexico, USA).