Temporal trends of polychlorinated biphenyls serum levels in subjects living in a highly polluted area in Italy from 2003 to 2015: a population-based cohort study.

Abstract

Introduction A chemical factory located in Brescia, an industrialized town in North Italy, produced polychlorinated biphenyls since the 1930s to the 1980s, determining a relevant pollution of soil, food and people. Since 2001, after a survey carried out in the general population living in the town, the individuals with serum levels of polychlorinated biphenyls higher than the reference entered a follow-up study for evaluating the temporal trend of their polychlorinated biphenyls serum levels. Methods We performed a prospective cohort study including subjects with at least three polychlorinated biphenyls measures during the period 2003-2015. We evaluated the temporal trends of total polychlorinated biphenyls serum levels using mixed models with a cubic-spline for time. We also stratified the analysis for the most commonly found congeners (IUPAC codes 138,153, 170, 180, 194 and 209) and subjects’ age. Results A total of 128 subjects were enrolled (mean age 57.7 years). The mean of polychlorinated biphenyls decreased from 58.35 ng/ml at the beginning (0-3 years) to 40.62 ng/ml at the end (9-12 years) of the follow-up. Polychlorinated biphenyls reduction over time was confirmed when using multivariate mixed models adjusted for age, and when analysing the major congeners separately. Finally, we evaluated the temporal trend according to age tertiles using mixed models with cubic splines terms for polychlorinated biphenyls. From baseline to twelve years, mean values of polychlorinated biphenyls levels increased with age and decreased over time, for each age category: from 43.05 ng/ml to 26.57 ng/ml, from 54.95 ng/ml to 31.30 ng/ml and from 75.36 ng/ml to 49.42 ng/ml for ages ≤55 years, 56-65 and ≥66 years, respectively. Conclusions A significant decrease of the serum concentrations of polychlorinated biphenyls was observed in subjects with high values of these chemicals at enrolment, over a 12 year period. The decrease was evident for each congener and age group.