Blood lead and cadmium and birth weight among sub-arctic and arctic populations of Norway and Russia

Background. Delivering women and their newborns in the Kola Peninsula of Ru ssia and the neighboring arctic area of Norway were studied to explore rela tionships between maternal cadmium and lead status and birth weight as a pr egnancy outcome. Methods. Life-style information, maternal blood and cord blood specimens we re collected from 50 consecutive mother-infant pairs From hospital delivery departments in three Russian and three Norwegian communities. Pregnancy ou tcomes were verified by consulting medical records. Lead and cadmium were d etermined in the blood samples by electrothermal atomic absorption spectrom etry. Results. The median blood-cadmium concentration for the Russian mothers was 2.2 nmol/L (n=148) versus 1.8 nmol/L in the Norwegian group (n=114, p=0.55 ). A weak association was observed between maternal cadmium and amount smok ed (r=0.30, p<0.001); no correlation was found between maternal blood cadmi um and birth weight. The corresponding maternal lead values were 0.14 (Russ ia) and 0.06 mu mol/L (Norway), p<0.001. The latter lead concentration cons titutes one of the lowest adult population values reported to date. Materna l and cord blood lead levels were strongly correlated (r=0.88, p<0.001). In a multivariate linear regression model, maternal blood lead was recognized as a negative explanatory variable (p<0.05) for birth weight and child's b ody mass index (BMIC), with or without adjustment for gestational age. A si milar association was suggested by ANOVA-analysis of maternal blood lead by quartiles. Conclusion. Maternal blood-lead level as an environmental factor is an appa rent predictor of low birth weight and BMIC. It reduced substantially the c ontribution of a country factor in explaining the observed differences in b irth weight.