Epidemiology of birth defects, perinatal mortality and thyroid cancer before and after the Chernobyl catastrophe

Spatial and temporal trends of birth defects and perinatal mortality in Germany and Europe as well as in least and most contaminated regions have been compared and investigated by trends. In numerous data sets, especially from northern and eastern Europe, positive and significant trend variations with upward 'disturbances' in temporal relation associated with the Chernobyl accident 1986 have been identified and spatial associations with regional fallout have been found. A surprisingly consistent picture evolves of significantly raised stillbirth rates after Chernobyl of ca. 5 % in Poland, ca. 10 % in parts of Germany and Sweden, ca. 20 % in Denmark and Finland, and up to ca. 30% in Iceland and Hungary. Low as compared to higher contaminated regions show weaker or stronger effects, respectively. The additional relative risks for birth defects are in the same order of magnitude as the additional relative risks for stillbirth, namely 0,5%-20 %/kBq·m2. Using well-known conversion coefficients, the excess relative risk of 1 %/kBq·m2 translates theoretically to a preliminary relative risk of 1,6/mSv/a. The incidence of thyroid carcinoma among children affected by Chernobyl fallout has increased dramatically in certain parts of Europe. Less evidence exists for a similar effect among adolescents and adults. The cancer registry of the Czech Republic provides an opportunity to study various determinants of the occurrence of thyroid cancer. After the Chernobyl accident, the thyroid cancer incidence of the Czech Republic reveals an additional annual increase of up to 5% depending on age and gender. The additional increases of thyroid cancer in the whole population of the Czech Republic are consistent with reports from other countries. To investigate trends in the sex distribution of newborns before and after the Chernobyl accident, gender-specific annual birth statistics were obtained from the Czech Republic, Denmark, Finland, Germany, Hungary, Norway, Poland, and Sweden between 1982 and 1992. For special parts of Germany, annual birth statistics and fallout measurements after Chernobyl are available at the administrative district level. Trend models allowing for discontinuities of the male birth proportions are suggested. Superimposed on a downward trend in male proportions there was a 'jump' in 1987 with an odds ratio of 1,0047 (95%-confidence interval: 1,0013-1,0081, p-value: p = 0,0061). A positive association of the male proportion in Germany between 1986 and 1991 with radioactive exposure at the district level is reflected by an odds ratio of 1,0145 per mSv/a (1,0021-1,0271, p = 0,0218). These findings suggest a possible long term chronic effect of influence by the Chernobyl Nuclear Power Plant accident on the human sex odds at birth in several European countries. (authors)