Germany's Epidemiological Data on Cleft Lip and Palate After the Chernobyl Nuclear Power Plant Accident: A Systematic Literature Review.

BACKGROUND/OBJECTIVES: The aetiology of facial clefts remains incompletely understood, and ionising radiation has been discussed as a potential exogenous factor. This review investigated the epidemiology of cleft lip and/or palate (CL/P) in Germany in relation to the Chernobyl NPP accident. METHODS: A systematic literature search was conducted using MEDLINE, LIVIVO, and the Cochrane Library, supplemented by additional searches. OHAT risk-of-bias domains were applied to the included studies. RESULTS: In total, 276 potentially relevant records were identified, of which six were included. Studies from Bavaria and the former German Democratic Republic reported regional associations between increased CL/P prevalence and the Chernobyl NPP accident. None of the included studies assessed radiation exposure at the individual level; exposure assessment was regional or ecological. CONCLUSIONS: Associations were reported in some more heavily contaminated regions, whereas no statistically significant differences were found in regions affected by lower levels of fallout. One study reported an estimated additional regional exposure of 1.2 mGy in the most heavily contaminated areas. This estimate does not substitute for individual dosimetry and should be interpreted cautiously. Experimental and other sources cited in the review discuss malformation effects at doses of at least 50 mGy. Given the heterogeneous study designs, ecological exposure assessment, inadequate control of confounding, and very low certainty of evidence, the available data do not support establishing a causal relationship between Chernobyl-related exposure and CL/P in Germany.