Background: Cleft lip and palates (CLP) occur with a frequency of between 1 and 2 cases in 1000 live births and thus belong to the most frequent congenital anomalies. In the former German Democratic Republic (GDR), records covering 1967-1989 for CLP newborns show a 9.4% increase of the prevalence of CLP from 1987 to 1989, possibly due to Chernobyl. DATA AND STATISTICAL METHOD: In Bavaria, all congenital malformations in children's hospitals have been recorded from 1984 to 1991. Among these data, 1324 cases with CLP were found. A spatial-temporal analysis aimed at uncovering a possible association of the CLP occurrence with the Chernobyl fallout on a district level, as well as a synoptic analysis of the GDR and Bavarian data, were carried out.
Results: In Bavaria, from October 1986 to December 1990, the CLP frequency increased by 9.5% (p=0.10) relative to the trend as computed from the remaining years. The association of CLP rates with fallout on a district level is reflected by a significant relative risk (RR) per kBq/m(2) of RR=1.008 (p=0.03). A synoptic analysis of the Bavarian data and the GDR data restricted to the overlapping time window from 1984 to 1989 discloses a simultaneous significant jump of the CLP prevalence by 8.6% (p=0.02) after 1986.
Conclusion: The presumption of a long-term increase of CLP after exposure to Chernobyl fallout is corroborated by the analysis of the Bavarian congenital malformation data.