Age- and Concentration-Dependent Elimination Half-Life of 2,3,7,8-Tetrachlorodibenzo-p-dioxin in Seveso Children

Shorter elimination half-lives for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) have been reported in human infants (Kreuzer et al. 1997; Leung et al. 2006) and in highly exposed adults (Aylward et al. 2005; Leung et al. 2005) compared with those in the general population. However, few published elimination half-life data are available for young children and adolescents 1–18 years of age. Needham et al. (1997/1998) presented TCDD decay curves for a 50-year-old Seveso male (initial TCDD concentration of 1,770 ppt) and a 6-year-old Seveso male (initial TCDD concentration of 15,900 ppt) and noted a much faster TCDD serum lipid decay for the child, especially over the 6-year period following exposure. Additional data on children are needed to further validate the two age-dependent PCDD/F half-life models that have been proposed for estimating childhood body burdens (Kerger et al. 2005; Kreuzer et al. 1997). In this study we examined a database of longitudinal TCDD measurements in the blood lipids of children (ages 0.5–18 years) exposed during the 1976 trichlorophenol reactor explosion incident near Seveso, Italy. As many as 10 sequential measurements were made on some children. We evaluated changes in elimination rate of TCDD in blood lipids as influenced by age, latency from exposure, TCDD concentration or mass in the body, severity of chloracne, and body mass parameters potentially influencing the half-life in children, adolescents, and young adults. Our goal was to identify central tendency trends for the half-life versus age relationship that may be used to estimate childhood body burdens, particularly for children 1–7 years of age, an age range critical to understanding potential risks of PCDD/F intake during childhood (Kerger et al. 2005).