title: Unexpectedly long half-lives of blood 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) levels in Yusho patients.
abstract: BACKGROUND
  Dioxins and dioxin-like compounds have half-lives typically between 7.2 years and 15 years. Our previous study of patients poisoned by extremely high concentrations of 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) in the 'Yusho incident' in 1968 found that in some the half-life of blood 2,3,4,7,8-PeCDF tended towards infinity. This suggests that there are two groups of Yusho patients, those with 2,3,4,7,8-PeCDF half-lives around 10 years, and those with half-lives near infinity. We sought to establish the proportions of each in a cohort of 395 Yusho patients, and whether the proportions were changing over time.
  
  
  METHODS
  We undertook longitudinal measurement of the blood concentration of 2,3,4,7,8-PeCDF in our cohort between 2002 and 2010. We estimated the change in concentration for each patient using linear regression for measured 2,3,4,7,8-PeCDF concentration, then compared the distribution of changes in concentrations with our previous study.
  
  
  RESULTS
  In patients in whom the blood concentration of 2,3,4,7,8-PeCDF exceeded 50 pg/g lipid, the proportion 8.0% of patients exhibiting half-lives less than 13.3 years fell compared with our previous study (28.2%), while the proportion with near infinity half-lives increased.
  
  
  CONCLUSIONS
  The prolongation of the half-lives was likely a consequence of age-related factors.
authors.affiliation: Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara, Japan. shinyamatsumoto-tky@umin.ac.jp.
authors.forename: Shinya
authors.initials: S
authors.lastname: Matsumoto
authors.affiliation: Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara, Japan. makahane@naramed-u.ac.jp.
authors.forename: Manabu
authors.initials: M
authors.lastname: Akahane
authors.affiliation: Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara, Japan. y-kanagawa@jreast.co.jp.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kanagawa
authors.affiliation: Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka, Japan. kajiwara@fihes.pref.fukuoka.jp.
authors.forename: Jumboku
authors.initials: J
authors.lastname: Kajiwara
authors.affiliation: Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Japan. mchikage@dermatol.med.kyushu-u.ac.jp.
authors.forename: Chikage
authors.initials: C
authors.lastname: Mitoma
authors.affiliation: Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Japan. uchihir@dermatol.med.kyushu-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Uchi
authors.affiliation: Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Japan. furue@dermatol.med.kyushu-u.ac.jp.
authors.forename: Masutaka
authors.initials: M
authors.lastname: Furue
authors.affiliation: Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara, Japan. imamurat@naramed-u.ac.jp.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Imamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001572:Benzofurans / Q000378:metabolism*; D004785:Environmental Pollutants / Q000378:metabolism*; D005260:Female; D005506:Food Contamination; D006207:Half-Life; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D001572:Benzofurans; D004785:Environmental Pollutants; C038890:2,3,4,7,8-pentachlorodibenzofuran