Serum levels of polychlorinated biphenyls and stroke risk among Chinese: a hospital-based case–control study

Previous studies have revealed the serious human health risk effects of organic pollutants-polychlorinated biphenyls (PCBs). However, the roles of circulating PCBs on stroke risk have not been elucidated. The purpose of this study was to examine whether serum PCBs could increase the risk for stroke among Chinese participants. A total of 241 patients with stroke and age- (5-year interval) and gender-matched controls were recruited in Tianjin, China. Concentrations of 17 PCB congeners were measured by using high-resolution gas chromatography with mass spectrometric detection. Conditional logistic regression models were applied to assess the odds ratio (OR) and 95% confidential interval (CI). Significant positive associations were observed between serum total PCBs and dioxin-like PCBs and the risk for stroke (all p trends < 0.05), and the adjusted ORs for the highest tertile (T3) of serum concentration compared with the lowest tertile (T1) were 1.704 (1.073, 2.506) and 1.846 (1.156, 2.949). However, no significant association was found for non-dioxin-like PCBs (OR for T3 vs. T1: 1.388, 95%CIs: 0.850, 2.266; p trend: 0.118). Stratified analysis by stroke subtypes (ischemic or hemorrhagic strokes) showed no significant heterogeneity (OR for T3 vs. T1: 1.644 vs. 1.824; p for interaction: 0.458). The results suggest detrimental roles of PCBs, mainly dioxin-like PCBs, in stroke risk, irrespective of stroke subtypes. Further well-designed prospective studies with larger sample size are invited to confirm these associations.