Elbmarsch is a Samtgemeinde ("collective municipality") in the district of Harburg, in Lower Saxony, Germany. It is situated on the southern (left) bank of the river Elbe, approx. 30 km southeast of Hamburg, and 20 km north of Lüneburg. Its seat is in the village Marschacht. The name refers to the marshes (German: Marsch) along the Elbe.The Samtgemeinde Elbmarsch consists of the following municipalities: Drage  Marschacht TespeCancer clusterElbmarsch is the epicenter of a notable pediatric cancer cluster that persisted for over 15 years. Although a sparsely populated region a high rate of childhood leukemia was observed with an incidence in the region that is significantly higher compared to Germany as a whole. No unique hazards have been identified. The community is surrounded by two nuclear establishments. A possible accidental release of radionuclides in 1986 was hypothesized.Ionizing radiation is another exposure conclusively linked with childhood leukemia. Survivors (within 1000 m) of Hiroshima and Nagasaki developed leukemia 20 times more frequently than in unexposed populations.