昭和電工
Showa Denko responded to the outbreak of Niigata Minamata disease in a similar way that Chisso had responded in Minamata: by attempting to discredit the researchers while proposing their own theory. The company issued information leaflets that rejected their wastewater as the cause of the disease and suggested the cause might have been an "agricultural chemical run-off" that entered the river after the 1964 Niigata earthquake.