Objective To explore the association between mitochondrial DNA copy number (mtDNAcn) and blood lead level (BLL) in peripheral blood of lead-exposed workers.
Methods A total of 873 workers in a lead storage battery plant were recruited, including 193 workers without exposure to lead and other occupational risk factors (control group) and 680 workers only exposed to lead (exposure group). A questionnaire survey was conducted to collect general information. Hematological parameters were detected by routine blood test. Quantitative real-time PCR was performed to calculate relative mtDNAcn. BLL was determined by graphite-furnace atomic absorption spectrophotometry. The statistical methods of this study included generalized linear regression, polynomial generalized linear regression, and restricted cubic spline regression.
Results The medians (quartile ranges) of BLL were 218.90 μg/L (180.60 μg/L) among total workers, 65.50 μg/L (44.20 μg/L) in the control group, and 251.00 μg/L (141.05 μg/L) in the exposure group. In the control group, the medians (quartile ranges) of red blood cell (RBC) count, mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and hemoglobin (Hb) concentration were 4.71×1012/L (0.77×1012/L), 29.20 pg (2.00 pg), 316.00 g/L (9.00 g/L), and 139.00 g/L (26.00 g/L), respectively. The corresponding indicators were 4.83×1012/L (0.74×1012/L), 28.80 pg (2.00 pg), 313.00 g/L (10.00 g/L), and 140.00 g/L (21.00 g/L) in the exposure group, respectively. Compared with the control group, the exposure group showed increased BLL (P < 0.01), and decreased RBC count, MCH, MCHC, and Hb concentration (bs < 0 and Ps < 0.05). The relative mtDNAcn of the exposure group was lower than that of the control group (b=-0.13, P=0.04). When BLL was in the range of 8.90-275.86 μg/L, the relative mtDNAcn decreased with in creasing BLL (b=-0.001 6, P < 0.01), but when BLL was in the range of 275.86-647.70 μg/L, the relative mtDNAcn increased with in creasing BLL (b=0.000 002 9, P=0.02).
Conclusion Peripheral blood mtDNAcn is associated with BLL in selected lead-exposed workers, suggesting that occupational le ad exposure could induce damage and dysfunction in mitochondria. Moreover, mtDNAcn has the potential to be a biomarker of le ad exposure.
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