Prevalence at birth of congenital anomalies in a population living around a modern municipal solid waste incinerator.

Introduction. Chemicals emitted by the municipal waste incinerators are suspected to increase risk of birth defects in exposed populations. We examined the prevalence at birth of congenital anomalies in offspring of women potentially exposed to the emissions of a municipal solid waste incinerator.Methods. Within a health surveillance program monitoring reproductive health in the population (around 180,000) of an Italian city where a modern incinerator has been operating for thelast few years, we identified all pregnancies occurring in 2003-04 in two cohorts of women aged 16-49, residing in two exposure areas close to the incinerator plant: area A, with the highestexposure, and area B, with intermediate exposure. We also identified the pregnancies occurring in two cohorts of women aged 16-49 who were working in the A and B areas in 2003. Weretrieved birth defects from livebirths and stillbirths through the Emilia-Romagna region hospital discharge records and the regional registry of congenital malformations named IMER. Wecalculated the age-adjusted relative risk (RR) of prevalence at birth of congenital anomalies in newborns to women belonging to the A and B cohorts, using prevalence in the remainingmunicipal population as reference rate. We also retrieved individual data about socioeconomic status from the General Registry Office for the two exposure cohorts and for the remainingmunicipal female population.Results. In the offspring of women having the highest exposure (cohort A) we did not observe any case of birth defects whilst 0.41 cases were expected in 2003-04. In the same period, wedetected two cases of congenital anomalies among newborns to women having intermediate exposure (cohort B), whilst the number of expected cases was 3.42, yielding a RR of 0.6 (95%confidence limits 0.1-1.9, P-value 0.480). We detected one case in offspring of employees working in the A area (RR 2.1, 95% confidence limits 0.1-10.3, mid-P-value 0.464) and no cases innewborns to employees working in the B area vs. 0.26 expected cases. Socioeconomic status of exposed cohorts did not appear to be higher than in the remaining municipal population.Discussion and conclusions. Results of this study seem to suggest that residence in the proximity of a modern municipal waste incinerator does not exert major teratogenic effects, al leastwith reference to the risk of birth defects in offspring. The low statistical stability of the point estimates, however, warrants further follow-up of the study cohorts