Change in decay rates of dioxin-like compounds in Yusho patients.
Once ingested, dioxins and dioxin-like compounds are excreted extremely slowly. Excretion can be evaluated by its half-life. Half-lives estimated from observed concentrations are affected by excretion and ongoing exposure. We investigated the change in apparent half-life using a theoretical model based on exposure to dioxin and dioxin-like compounds.



We carried out longitudinal measurements of the blood concentration of dioxins and dioxin-like compounds in a Yusho cohort during 2002 to 2010. We estimated the change in decay rates of 2,3,4,7,8-PeCDF and octachlorodibenzodioxin (OCDD) using a second-order equation.



We found that the decay rate of OCDD increased, whereas the decay rate of 2,3,4,7,8-PeCDF of patients with a relatively high concentration of 2,3,4,7,8-PeCDF decreased. OCDD results were in accordance with decreasing levels of dioxin and dioxin-like compounds in the environment. The decay rate of OCDD in the body was affected by the decay rate of OCDD in the environment by ingestion because it was near the steady-state. In contrast, the decay rate of 2,3,4,7,8-PeCDF in the body was affected less by ingestion from the environment because it was far higher than in the steady-state.



We demonstrated that the level of 2,3,4,7,8-PeCDF in the environment is decreasing. The excretion half-life is longer than the environmental half-life, thus the excretion half-life in a Yusho patient is increased.
Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara, 634-8521, Japan. shinyamatsumoto-tky@umin.ac.jp.
Shinya
0000-0001-5719-9709
S
Matsumoto
Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara, 634-8521, Japan.
Manabu
M
Akahane
Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara, 634-8521, Japan.
Yoshiyuki
Y
Kanagawa
Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka, Japan.
Jumboku
J
Kajiwara
Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, , Higashi-ku, Fukuoka, Japan.
Chikage
C
Mitoma
Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, , Higashi-ku, Fukuoka, Japan.
Hiroshi
H
Uchi
Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, , Higashi-ku, Fukuoka, Japan.
Masutaka
M
Furue
Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara, 634-8521, Japan.
Tomoaki
T
Imamura
D001822:Body Burden; D004147:Dioxins / Q000097:blood*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000097:blood*; D005506:Food Contamination; D006207:Half-Life; D006801:Humans; D007564:Japan
D004147:Dioxins; D004785:Environmental Pollutants
2,3,4,7,8-pentachlorodibenzofuran (PeCDF); Aging; Dioxin; Dioxin-like compounds; Half-life; Yusho