Infant mortality in Poland
Poland which has borders with Belarus and Ukraine is likely to be more contaminated from the Chernobyl fallout than Germany. In addition, Poland has a rather large population of nearly 40 mio. Data from Poland may support the findings of increased perinatal mortality data in Germany.
Unfortunately I could not get monthly data of perinatal mortality from Poland. Therefore monthly data of infant mortality, 1981 through 1991, were used.
For the data analysis, a non-linear regression model is applied (statistical package R, function nls):
fm <- nls(p~1000/(1+1/exp(c0+c1*x+c2*cos(2*pi*(x-c3))+c4*cos(2*pi*(2*x-c5))+c6*cs+c7*cs^2)),
x is time where x=t-1980 and t is calendar year.
model fit to the data shows large overdispersion (SSE=332.2; df=124, dispersion
parameter OD=2.68). Therefore a regression for a restricted time interval,
1985-1989, was conducted. It yielded SSE=80.2; DF=52; OD=1.54.
infant mortality in Poland - like perinatal mortality in Germany - is associated
with the delayed caesium burden of pregnant women.
Figure 2 shows the residuals, ie the deviations of the data from the model fit, in units of standard deviations (standardised residuals). In January 1987 and in April 1987 infant mortality rates are significantly increased.
Figure 3 displays the association between infant mortality and delayed caesium burden. The y-axis shows the ratio of observed to expected infant mortality rates (relative risk).