Perinatal mortality, congenital malformations, spontaneous abortions

Perinatal mortality annual data from Germany and Poland show significant increases in 1987, the year following the Chernobyl accident, relative to the long term trend. In an analysis of German monthly perinatal mortality data, peaks of perinatal mortality in the beginning and at the end of 1987 are found. Both peaks are associated with peaks of the caesium burden in pregnant women 7 months earlier (95% CI: 5.5 to 8.5 months). Infant mortality monthly data from Poland exhibit the same pattern. The association with the delayed caesium concentration is highly significant. A combined regression of early neonatal mortality data from Germany and infant mortality data from Poland finds a curvilinear dose response relationship with an estimated power of dose of 2.8 ± 0.8.

In Austria, one of the countries with the highest average fallout levels outside the former Soviet Union, perinatal mortality decreased in 1987 relative to the long-term trend. The analysis of monthly perinatal mortality data yields an inverse dose dependency at lower doses, followed by an increase at higher doses.

Perinatal mortality in Gomel, the most contaminated region of Belarus, is compared with the rest of Belarus. Perinatal mortality rates do not differ significantly until 1988 but then the rate in Gomel increases relative to the rates in the rest of Belarus and stays about 30% higher until 1998. This increase can be explained as a late effect of strontium uptake. Data from the Ukrainian regions Zhytomyr and Kiev, with the highest levels of fallout in Ukraine, yield similar results.

Data of congenital malformations were only available for Bavaria, the German federal state with the highest fallout level. An association of malformation rates with caesium soil contamination is found at the end of 1987, seven months after a peak of caesium burden of pregnant women in April and May 1987.

In February 1987, a significant 11.4% drop of birth rate is observed in Bavaria which might be explained by an increased rate of spontaneous abortions 9 months earlier, in May 1986. In the most contaminated Ukrainian regions Zhytomyr and Kiev, the birth rate dropped by 25% in February 1987.

The health effects reported here all show a temporal correlation with the radiation exposure from Chernobyl. According to conventional radiobiological knowledge, no teratogenic effects are expected to occur below a threshold dose of about 100 mSv. Even in the most contaminated regions of Germany, however, the extra doses to the foetus were below 1 mSv in the first follow-up year. Therefore the results contradict the widely accepted concept of a threshold dose for radiation damage during foetal development.