True about Minamata disease are all except:

Knowledge about the extreme vulnerability of the fetus to methylmercury began with the Minamata Bay, Japan experience. The bay was heavily contaminated with methylmercury from industrial discharge. Fish bioconcentrated the toxicant and mothers acquired high blood levels from eating fish from the bay. While the mothers were usually without symptoms of mercury poisoning, their babies were born severely damaged with microcephaly, cerebral palsy, severe mental retardation, seizure disorders, blindness, deafness and other malformations. Ref :