Environmental exposure assessment in European birth cohorts: results from the ENRIECO project

Pregnancy and birth cohort studies provide the possibility of repeated measurements of health outcomes and exposures at different time points from pregnancy through childhood and adolescence into adulthood. Therefore, they present an ideal framework for the prospective study of the effects of environmental exposures on the health and development of children. Furthermore, they allow the study of temporal variability in exposure. If temporal variability is sufficient, the relevance of exposure at different time points (e.g. prenatal and postnatal) and the health impact associated with changes in exposure can be investigated, which may help to focus preventive actions.Currently, many European birth cohort studies of children’s environment-health relationships exist and provide evidence for relationships that can be used to develop strategies to reduce environmental exposures and to improve health. However, single studies often lack statistical power to lead to conclusive results on their own, in particular when health outcomes and/or exposures with low prevalence are studied. Combining data from different studies is a powerful remedy for this. Also, collaboration between birth cohorts enables us to replicate and corroborate or refute findings as well as to explore reasons for heterogeneity. Therefore, there is an urgent need to evaluate, and where possible combine, the existing data, methods and tools from European birth cohort studies in order to evaluate possible links between environmental exposures and health [1].The assessment of exposure is a crucial element of the study of the potential adverse effects associated with exposure. Error in exposure measurements reduces the statistical power of a study [2] and the estimated effect is likely to be smaller than the true effect [3], both increasing the likelihood that real associations are not detected. Exposure can be assessed by means of direct approaches including biological and personal monitoring, by means of indi