Toroku arsenic disease (土呂久砒素公害, Toroku hiso kōgai) was a disease resulting from air and water pollution from a refinery at a mine at Toroku, located in Takachiho, Nishiusuki District, Miyazaki, Japan.
It emitted arsenic-containing air, resulting in patients with chronic arsenic poisoning producing skin changes, skin cancers and sometimes lung cancer. The Sumitomo Metal Mining Co., Ltd., which bought the right of mining, was sued by the patients for health damage, but 15 years later, the lawsuit ended with a compromise.[citation needed]
The pollution at Toroku dates back to 1690 according to A Table of Public Hazards of Japan[1]
Seven patients were examined extensively at Kumamoto University, and they were diagnosed as having chronic arsenic poisoning due to pollution, in a report published in 1973.[2] The same team increased the number of patients to 48 in 1976, while Hotta and his co-workers made extensive studies of the pollution.[3]
Nakamura et al. characterized the condition by pigmentation which is either macular or diffuse, appearing both in covered and exposed areas. Punctate depigmentation appears in raindrop shapes, and hard keratoses are either localized or diffuse. Malignant changes may occur. They pointed out nasal septum defects. The environmental agency first indicated the skin and ENT findings of nasal scar or septum defect as necessary symptoms for the Toroku Pollution.
In addition to the skin and ENT findings, neuritis was added as a criterion of chronic arsenic poisoning. Bowen's disease, Lung cancer, and cancer of the urinary organ were added as appearing following chronic arsenic poisoning.