The congenital anomalies registry in Belarus: a tool for assessing the public health impact of the Chernobyl accident.

A national population-based malformation registry (BNR) has been in operation since 1979 in Belarus, one of the countries most heavily exposed to the contamination from the Chernobyl accident of 26 April 1986. We describe its methodology and its compliance with established criteria, evaluate the completeness of its reporting, and analyze the data collected in four administrative regions with contrasting contamination levels from 1983 through 1999. Nine easily diagnosed malformations have been monitored since 1983. Reporting completeness exceeds 85% for all periods and all regions. In all periods, the prevalence at birth of these malformations was lower in the most contaminated regions and showed a similar positive time trend in areas of low and high contamination. We conclude that the BNR is a reliable tool for studying the possible effects on congenital malformations caused by the Chernobyl accident. Although the trend we observed may be explained by better ascertainment and prenatal diagnosis, a real increase cannot be ruled out.

[Down syndrome and ionizing radiation: causal effect or coincidence]. / Sindrom Dauna i ioniziruiushchaia radiatsiia: prichinno-sledstvennaia sviaz' ili sluchainaia zavisimost'.

Annual and monthly prevalence of Down's Syndrome has been analyzed in Belarus for a 19-year period (1981 to 1999). The distribution of 2786 DS cases during this period showed no significant long-term prevalence trend. Meanwhile, 2 marked increases of DS prevalence were registered in 1987 and 1990. The most remarkable annual increases were observed in 1987 in Minsk city, in Vitebsk oblast (considered as contamination-free administrative district) and in Minsk oblast (partially contaminated area), data not shown in the text. Much more marked and significant increases were recorded in January 1987, in Minsk city, Gomel oblast and Minsk oblast. However it is impossible to establish a causal relationship between these clusters of DS and exposure to the Chernobyl fallout, at a geographical level. The presence of such a cluster 9 months after the explosion in one of the most exposed area (Gomel oblast) should incite to careful conclusions and prompt further studies.