Persistent hematologic and immunologic disturbances in 8-year-old Dutch children associated with perinatal dioxin exposure. ten Tusscher GW, Steerenberg PA, van Loveren H, Vos JG, von dem Borne AE, Westra M, van der Slikke JW, Olie K, Pluim HJ, Koppe JG. Department of Paediatrics and Neonatology, Emma Children's Hospital, Academic Medical Centre, PO Box 22660, 1100 DD Amsterdam, The Netherlands. g.w.ten.tusscher@planet.nl Perinatal exposure to Dutch "background" dioxin levels in 1990 was high, but comparable with that of other industrialized Western European countries. Exposure during the sensitive perinatal period may cause permanent disturbances. Therefore, we assessed the health status and various hematologic and immunologic parameters among our longitudinal cohort. A medical history was taken and venipuncture performed in a longitudinal cohort of 27 healthy 8-year-old children who had documented perinatal dioxin exposure. Linear regression revealed a decrease in allergy in relation to prenatal (p = 0.02) and postnatal (p = 0.03) dioxin exposure. Increases in CD4+ T-helper cells (p = 0.006) and in CD45RA+ cells (p = 0.02) were seen in relation to postnatal exposure. A persistently decreased platelet count (p = 0.04) and increased thrombopoietin concentration (p = 0.03) were seen in relation to postnatal exposure. This follow-up has shown a decrease in allergy, persistently decreased thrombocytes, increased thrombopoietin, and increased CD4+ T-helper and increased CD45RA+ cell counts. This study provides indications of effects at the stem cell level of perinatal dioxin exposure, persisting until minimally 8 years after birth