Background: During 1990-1991 a childhood leukemia cluster was observed in the sparsely populated region surrounding two nuclear establishments southeast of Hamburg, Germany. Since then, several new cases have been reported. Recently a possible accidental release of radionuclides in 1986 was hypothesized.

Objective: The objective of this study was to analyze the childhood leukemia incidence in this area since 1990.

Methods: All incident cases (< 15 years of age) were ascertained during 1990-2005 within a 5-km radius of the Krümmel nuclear power plant. We derived standardized incidence ratios (SIRs) using county and national leukemia incidence rates as referents. We stratified analyses by calendar period and attained age, and by subdividing the study region into areas north versus south of the Elbe river.

Results: Fourteen cases were ascertained in the study area, whereas 4.0 were expected based on national referent rates [1990-2005: SIR = 3.5; 95% confidence interval (CI), 1.9-5.9]. The excess was not confined to the early 1990s; for the more recent time period 1999-2005, the SIR is still elevated (SIR = 2.7; 95% CI, 0.9-6.2). SIRs of greatest magnitude were observed for children 0-4 years of age (SIR = 4.9; 95% CI, 2.4-9.0) and for residents south of the Elbe (SIR = 7.5; 95% CI, 2.8-16.4).

Conclusions: The incidence in this region is significantly higher than the childhood leukemia incidence for Germany as a whole. To date, no unique hazards have been identified in this population. The fact that the elevated rates have persisted in this community for > 15 years warrants further investigation.