Critical Appraisal of the 1977 Diagnostic Criteria for Minamata Disease

ABSTRACT

Large-scale food poisoning caused by methylmercury was identified in Minamata, Japan, in the 1950s (Minamata disease). Although the diagnostic criteria for the disease remain current, few studies have been carried out to assess the diagnostic accuracy of the criteria. From a 1971 population-based investigation, data from 2 villages were selected: Minamata (high-exposure area; n = 779) and Ariake (low-exposure area; n = 755). The authors examined the prevalence of neurologic signs characteristic of methylmercury poisoning and the validity of the criteria. A substantial number of residents in the exposed area exhibited neurologic signs even after excluding officially certified patients. Using paresthesia of the extremities as the gold standard of diagnosis, the criteria had a sensitivity of 66%. The current diagnostic criteria as well as the official certification system substantially underestimate the incidence of Minamata disease.

KEYWORDS:

• environmental pollution
• epidemiological studies
• methylmercury compounds
• Minamata disease
• sensitivity and specificity

Acknowledgments

The 1971 investigation was funded by the Kumamoto Prefectural Government. The study sponsor in study design has no role on the collection, the analysis, the interpretation of data, the writing of the article, and the decision to submit it for publication Ethical review committee did not exist in 1971, but informed consent was obtained orally by doctors in the 1971 investigation. The authors (T.T. and M.H.) declare that they have provided expert testimony in Minamata disease trials.

The authors appreciate the contributions of the late Professor Seijun Tatetsu for the study planning and of the staff in the Department of Neuropsychiatry, Kumamoto University School of Medicine. The authors also thank Saori Kashima helped us to make the figure.

Notes

Dr. Harada passed away on June 11, 2012