Risk of congenital anomalies near municipal waste incinerators in England and Scotland: Retrospective population-based cohort study

Background: Few studies have investigated congenital anomalies in relation to municipal waste incinerators (MWIs) and results are inconclusive. Objectives: To conduct a national investigation into the risk of congenital anomalies in babies born to mothers living within 10 km of an MWI associated with: i) modelled concentrations of PM10 as a proxy for MWI emissions more generally and; ii) proximity of residential postcode to nearest MWI, in areas in England and Scotland that are covered by a congenital anomaly register. Methods: Retrospective population-based cohort study within 10 km of 10 MWIs in England and Scotland operating between 2003 and 2010. Exposure was proximity to MWI and log of daily mean modelled ground-level particulate matter ≤10 μm diameter (PM10) concentrations. Results: Analysis included 219,486 births, stillbirths and terminations of pregnancy for fetal anomaly of which 5154 were cases of congenital anomalies. Fully adjusted odds ratio (OR) per doubling in PM10 was: 1·00 (95% CI 0·98–1·02) for all congenital anomalies; 0·99 (0·97–1·01) for all congenital anomalies excluding chromosomal anomalies. For every 1 km closer to an MWI adjusted OR was: 1·02 (1·00–1·04) for all congenital anomalies combined; 1·02 (1·00–1·04) for all congenital anomalies excluding chromosomal anomalies; and, for specific anomaly groups, 1·04 (1·01–1·08) for congenital heart defect sand 1·07 (1·02–1·12) for genital anomalies. Discussion: We found no increased risk of congenital anomalies in relation to modelled PM10 emissions, but there were small excess risks associated with congenital heart defects and genital anomalies in proximity to MWIs. These latter findings may well reflect incomplete control for confounding, but a possible causal effect cannot be excluded.