Association of plasma polychlorinated biphenyls concentrations and blood routine indicators in community-dwelling older adults in a city in Jiangsu Province

Background Exposure to polychlorinated biphenyls (PCBs) during pregnancy can affect hematological indicators and has the potential to reduce immune response during early pregnancy, but there are limited studies on their adverse health effects on older adults.

Objective This study explores the associations between plasma PCBs levels and blood routine indicators in community-dwelling older adults.

Methods From August 2014 to February 2015, a total of 150 community-dwelling adults above 60 years old were recruited, and routine blood examinations and basic information surveys were conducted. The exposure levels of six PCB congeners (PCB28, PCB52, PCB101, PCB138, PCB153, and PCB180) in plasma were detected by gas chromatography-tandem mass spectrometry (GC-MS/MS). The associations of the concentrations of PCB101 (positive rate above 50%), the sum of three low chlorinated congeners (Σ₃LPCBs), and the sum of six PCBs (Σ₆PCBs) with blood routine indicators or ratio indicators were analyzed using multiple linear regression models adjusted for sex, age, education level, marital status, monthly income per capita, smoking, drinking, and chronic diseases.

Results At least one PCBs congener was positive in 92.67% of the 150 community-dwelling older adults. Among the six congeners, PCB101 showed the highest positive rate (72.67%), with a median of 9.38 ng·g^-1 (calculated by lipid). The median concentrations of Σ₃LPCBs and Σ₆PCBs were 18.96 and 33.68 ng·g^-1 (calculated by lipid) respectively. The medians interquartile ranges, (IQR) of counts of white blood cells, red blood cells, and platelets of the elderly were 5.16×10⁹ (1.90×10⁹), 4.56×10¹² (0.53×10¹²), and 157.50×10⁹ (61.25×10⁹) L^-1, respectively. The multiple linear regression results showed that for every IQR increase in exposure level of Σ₆PCBs in plasma 12.3ng·g^-1 (calculated by lipid), the lymphocyte count (-4.77%, 95% CI: -8.53% - -1.01%) and lymphocyte percentage (-3.57%, 95% CI: -6.42% - -0.72%) decreased significantly, the neutrophil percentage (1.97%, 95% CI: 0.24%-3.71%) increased significantly, and the mean corpuscular volume (-0.52%, 95% CI: -0.99% - -0.05%) and mean corpuscular hemoglobin (-0.62%, 95% CI: -1.16% - -0.09%) decreased (P< 0.05). For every IQR increase in exposure levels of PCB101 and Σ₆PCBs in plasma 8.8 and 12.3 ng·g^-1 (calculated by lipid), the decrease of platelet count (-2.93%, 95% CI: -5.58% - -0.29%; -3.60%, 95% CI: -6.90% - -0.30%) and platelet distribution width (-3.17%, 95% CI: -5.48% - -0.85%;-3.58%, 95% CI: -6.47% --0.69%) and the increase of platelet hematocrit (1.27%, 95% CI: 0.35%-2.19%; 1.53%, 95% CI: 0.38%-2.67%) showed significant differences (P< 0.05). For every IQR increase in exposure levels of PCB101, Σ₃LPCBs, and Σ₆PCBs in plasma 8.8, 7.7, and 12.3 ng·g^-1 (calculated by lipid), the increase of platelet-large cell ratio (3.17%, 95% CI: 0.50%-5.84%; 3.50%, 95% CI: 0.32%-6.68%; 3.99%, 95%CI: 0.68%-7.31%) showed significant differences (P< 0.05). Additionally, an IQR increment in Σ₆PCBs 12.3ng·g^-1 (calculated by lipid) was significantly associated with the percentage changes of lymphocytes-to-monocytes ratio, which was 16.44% (95%CI: 1.41%-31.48%, P< 0.05).

Conclusion Exposure to PCBs in plasma may lead to quantitative and morphological changes of white blood cells, red blood cells, and platelets in selected community-dwelling older adults.