Michiko Ishimure, an award-winning author and social critic whose works put the spotlight on what became known as Minamata disease, died early Saturday due to acute exacerbation of Parkinson’s disease. She was 90.

A native of Kumamoto Prefecture, the prolific Ishimure is known for raising public awareness of the mercury poisoning issue. Her literary works include “Kugai Jodo,” the English title of which is “Paradise in the Sea of Sorrow.”

Minamata disease paralyzes the central nervous system and causes birth defects. After Chiso Corp. poisoned Minamata Bay with years of mercury discharges, sickening thousands and causing hundreds of deaths, the government recognized it as a pollution-caused disease in September 1968.