the Elbe, is nuclear reprocessing plants in France. A 2010 report exonerated the nuclear power plants on the Elbe as the cause of contamination. Further doubt was cast on the nature of the supposed beads of nuclear material, with a Federal commission chastising the original commission that claimed to have discovered the beads. The exact cause of the increased leukemia cases remains unknown, and could be due to other environmental factors, or even by chance. The community surrounding the Savannah River nuclear facility in the U.S. was chosen for comparison with the “cluster” noted around the Kruemmel site. The tritium burden around the Savannah River site is significantly higher than the measured burden in Germany; however, the incidence of leukemia in South Carolina was not increased. Differences in population density, proximity to the power plant, and route of tritium exposure (inhalational versus oral via drinking water) may account for the lack of correlation between the two sites, or there may be alternative explanations for the increased incidence of hematopoietic malignancy between 1989 and 1991 in Elbmarsch. Some of these alternative hypotheses have included electromagnetic fields, parental radiation exposure prior to conception, other carcinogens, and benzene exposure; however, none have been supported by the existing evidence. Intriguingly, a larger case-control study in Lower Saxony found a correlation between the “untrained immune system” (as judged as contact with other children, vaccinations, etc.) and leukemia risk, suggested that an immature immune system that has not been challenged is at greater risk for developing malignancy, possibly secondary to an undefined environment insult. References Samtgemeinden in Lower Saxony Harburg (district) Cancer clusters