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Perinatal mortality in Belarus and Ukraine before and after Chernobyl Alfred Körblein Munich Environmental Institute Munich, Germany

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Objective of the study To test perinatal mortality rates in highly contaminated regions of Belarus and Ukraine for a possible association with the radiation burden of pregnant women

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Caesium burden in pregnant women

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Perinatal mortality in Germany

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Perinatal mortality in Poland

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Residuals

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Perinatal mortality in England and Wales

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Perinatal mortality in the oblasts of Belarus

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Problems with trend analysis: 1.Definition change of stillbirths in 1994 2.Possible influence of socio-economic factors after the break-up of Soviet Union in 1991 Therefore: Comparison of perinatal motality rates in Gomel to the rates in the rest of Belarus except Minsk City, assuming that other influencing factors act equally in study and control region

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Study and control area

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Odds ratios odds ratio (OR) = p1/(1-p1) / (p0/(1-p0)) where p1 mortality rate in study area (Gomel) p0 mortality rate in control area for p0, p1 << 1: OR ~ RR = p1/p0 = relative risk

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Ratio of mortality rate in Gomel to rate in control area

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Increased perinatal mortality in the 1990‘s – a late effect from Chernobyl? Hypothesis: Increase of perinatal mortality is associated with strontium burden of pregnant women

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Strontium deposition near the Chernobyl site

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from: E.I. Tolstykh et al. Analysis of strontium metabolism in humans on the basis of the Techa river data. Radiat Environ Biophys (1997) 36: 25-29 Strontium retention in a woman as a function of age before and after menarche from: E.I. Tolstykh et al. Analysis of strontium metabolism in humans on the basis of the Techa river data. Radiat Environ Biophys (1997) 36: 25-29

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Calculation of strontium burden of pregnant women Approximation: Strontium uptake at age 14 (menarche) and in 1986 only Average strontium concentration Sr(t) depends on: 1.percentage of pregnant women aged 14 in 1986, i.e. born in 1972: Sr(t) ~ (t-1972), where t is calendar year and A(age) is the maternal age distribution 2.strontium excretion, determined by biological half-life T ½ : Sr(t) ~ exp(-ln(2)·(t-1986)/ T ½ )

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Maternal age distribution in Belarus

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Regression model ln(OR) = ln(1+c 0 +c 1 ·d 87 +c 2 ·Sr(t)) with d 87 = dummy variable for 1987 Sr(t) = calculated strontium concentration in pregnant women and weights: σ² = 1/n 1 + 1/(N 1 -n 1 ) + 1/n 0 + 1/(N 0 -n 0 ) n 1, n 0 = number of perinatal deaths N 1, N 0 = number of births in Gomel (1) and rest of Belarus minus Minsk City (0)

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Odds ratios of perinatal mortality (Gomel vs. Belarus minus Gomel and Minsk City)

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Regression results Comparison of sum of squares obtained in regressions without (red line) and with (blue line) the strontium term. From the difference of sum of squares, a p-value of p=0.0006 is determined (F-test) This corresponds to 388 excess perinatal deaths in the observation period

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Ukraine Data: Monthly data of perinatal mortality, 1985-91, for three oblasts: Kiev region, Kiev City, Zhytomyr

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Perinatal mortality in Kiev, Kiev City, Zhytomyr

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Combined regression model Linear logistic regression model for perinatal mortality E(Y(t)) + seasonal components + strontium effect Data from 5/1986-12/1988 are omitted (possible caesium influence) E(Y(t)) = 1/(1+1/exp((c 1 +c 4 ·Sr(t))·city+(c 2 +c 5 ·Sr(t))·kiev +(c 3 +c 6 ·Sr(t))·zhytomyr+ c 7 ·t +(c 8 ·cos(2π·(t-c 9 ))·(city+region) +c 10 ·cos(2π·(2t-c 11 )))·city)) with parameters c 1,c 2,c 3 :intercepts c 4,c 5,c 6 :strontium terms c 7 :slope c 8 - c 11 :seasonal components (12 and 6 months period) city, kiev, zhytomyr are dummy variables identifing the data sets

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Regression results for Ukraine Kiev City Kiev region Zhytomyr

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Kiev City

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Kiev region

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Zhytomyr

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Infant mortality in Poland

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Conclusion Perinatal mortality in Gomel is associated with strontium burden in pregnant women Strontium effect on perinatal mortality in Ukraine is greater in Zhytomyr than in Kiev region and is not significant in Kiev City Perinatal mortality in Zhytomyr exhibits a peak in the beginning of 1987 which is associated with the caesium burden in pregnant women

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