Temporal trends of polychlorinated biphenyls serum levels in subjects living in a highly polluted area from 2003 to 2015: a follow-up study.

Introduction: A chemical factory located in Brescia, an industrialized town in North Italy, produced polychlorinated biphenyls (PCBs) since the 1930s to the 1980s, determining a relevant pollution of soil, food and people. Since 2001, following a survey carried out in the general population living in the town, the individuals with PCB serum levels higher than the reference entered a follow-up study.

Methods: We performed a prospective cohort study including subjects with at least three PCB measures during the period 2003-2015. We evaluated the temporal trends of total PCB serum levels, the most common PCB congeners (PCB 138,153, 170, 180, 194 and 209), and toxic equivalency of dioxin-like PCBs using univariate and multivariate mixed models with and without a cubic-spline term for time.

Results: A total of 128 subjects were enrolled (46.1% males, mean age at enrolment 57.7 years). The geometric mean of PCBs decreased from 35.4ng/ml at 0-3 years to 29.3ng/ml at 4-8 years and to 23.0ng/ml at 9-12 years. A 3.8% reduction of total PCB serum levels per year was estimated using both univariate and multivariate mixed models adjusted for age; a similar reduction was found for the most common PCB congeners and for toxic equivalency. Total PCB serum levels decreased over time for each age group: -3.9%, -4.0% and -3.4% for subjects aged ≤55 years, 56-65 and ≥66 years, respectively.

Conclusion: A significant decrease of serum concentrations of PCBs was observed in subjects with high serum levels of these chemicals at enrolment over a twelve year period. The decrease was evident for each PCB congener and age group.