Substantial decline of polychlorinated biphenyls (PCBs) serum levels 10 years after public health interventions in a population living near a contaminated site in Northern Italy

Abstract

Introduction: In a large urban area in Northern Italy, a chemical factory producing Polychlorinated biphenyls (PCBs) from the 1930s to the 80s caused soil pollution that entered the food chain. Since 2001 public health interventions have been implemented to avoid human contamination. Methods: In a 2003 random sample survey, 537 adult residents, stratified for age and areas with different soil contamination, were tested for PCB plasma levels (24 congeners): residential and occupational history as well as current and past diet were investigated. In 2013, during a second survey using the same study design 488 residents were tested. Results: PCBs serum levels showed a strong correlation with age (Spearman r =0.71 in 2003 and 0.80 in 2013). Consumers of food produced in the most polluted area had higher levels (median=15.6 ng/ml in 2003 and 4.7 in 2013) than non-consumers (2003=4.1; 2013=2.3) and consumers of food produced in non polluted areas (2003=6,5; 2013=1,9) with a dose-effect gradient with cumulative local food intake. In a decade PCBs have declined by around half in all groups (P<0.001 for each comparison). The reduction was more evident in younger subjects ( 20-39 years: -58%; 40-59: -50%; 60-79: -27%; P<0.0001) and similar among all consumers groups. Congener profile was different among age groups, particularly in 2013: in 60-79 years old people high chlorinated CBs, the more persistent ones, represented 57,7% of total PCBs (36.6% among 20-39) with a mean value 19 times higher than in the younger (5.2 versus 0.27 ng/ml) while low chlorinated congeners, the less persistent one, were only 3.6 time higher (0,31 versus 0,09 ng/ml). Conclusions: High PCBs levels are still present in the elderly due to past exposure to local contaminated food. PCBs food chain contamination and human absorption have been interrupted successfully, suggesting that, while waiting for environmental remediation, public health measures need to be maintained.