title: Long-term exposure to methylmercury and psychiatric symptoms in residents of Minamata, Japan.
abstract: BACKGROUND
  It is well-known that prenatal or postnatal exposure to methylmercury can produce neurological signs in adults and children, exemplified by a case of large-scale poisoning in Minamata, Japan, in the 1950s. However, evidence regarding whether pre- or postnatal exposure to methylmercury causes psychiatric symptoms (e.g., impairment of intelligence and mood and behavioral dysfunction) is still limited-excluding cases of fetal Minamata disease patients.
  
  
  METHODS
  We evaluated the effects of pre- or postnatal exposure to methylmercury on psychiatric symptoms using data derived from a 1971 population-based survey in Minamata and neighboring communities. We adopted residential areas as an exposure indicator and psychiatric symptoms as the outcome. Then, we estimated the adjusted prevalence odds ratio (POR) and confidence interval (CI) of psychiatric symptoms in relation to residential area.
  
  
  RESULTS
  There were 904 participants in Minamata (high exposure area), 1700 in Goshonoura (middle exposure area), and 913 in Ariake (low exposure area). Compared to the Ariake area, participants in the Minamata area manifested psychiatric symptoms more frequently: PORs for impairment of intelligence and mood and behavioral dysfunction were 5.2 (95% CI: 3.7-7.3) and 4.4 (95% CI: 2.9-6.7), respectively. Furthermore, participants with psychiatric symptoms in the Minamata area more frequently had neurological signs. Peaks in prevalence of psychiatric symptoms occurred around age 20 and in older age adults in the area. These findings did not change when we excluded those who had been officially certified as Minamata disease patients by that time.
  
  
  CONCLUSIONS
  The present study suggests a relationship between pre- or postnatal exposure to methylmercury and psychiatric symptoms among the general population in Minamata even after excluding officially certified patients.
authors.affiliation: Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan. yorichan@md.okayama-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Yorifuji
authors.forename: Toshihide
authors.initials: T
authors.lastname: Tsuda
authors.forename: Sachiko
authors.initials: S
authors.lastname: Inoue
authors.forename: Soshi
authors.initials: S
authors.lastname: Takao
authors.forename: Masazumi
authors.initials: M
authors.lastname: Harada
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004785:Environmental Pollutants / Q000506:poisoning*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007360:Intelligence / Q000187:drug effects; D007564:Japan / Q000453:epidemiology; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology; D020262:Mercury Poisoning, Nervous System / Q000453:epidemiology*; D008767:Methylmercury Compounds / Q000506:poisoning*; D009422:Nervous System Diseases / Q000453:epidemiology*; D016017:Odds Ratio; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D008767:Methylmercury Compounds