Human biomonitoring of polychlorinated biphenyls (PCBs) in plasma of former underground miners in Germany – A case-control study

Abstract Polychlorinated biphenyls (PCBs) are very persistent organic pollutants of severe environmental concern due to their toxic properties. Former underground miners might have been exposed to this substance group due to the widespread use of PCBs in hydraulic oils from the late 1960s to the mid 1980s. We have conducted a blinded case-control study in order to evaluate the possibility of retrospective exposure assessment of PCBs using human biomonitoring in former underground miners decades after the last possible exposure. We have identified n = 34 male former underground miners and n = 136 age-matched male control persons from the database of patients of our occupational outpatient clinic aged between 47.9 and 83.7 years  at the time of sampling (June 2006–June 2016). These archived plasma samples have been blinded and analysed for 21 different PCB-congeners using a validated and quality controlled procedure using GC/MS (LOQ: 0.01 μg/L). Highly significant differences between cases and age-matched controls were only found for the PCB-congeners PCB 74 and PCB 114. The median (95th percentile) levels of PCB 74 in cases and controls were 0.126 μg/L plasma (0.899 μg/L plasma) vs. 0.058 μg/L plasma (0.368 μg/L plasma) and the 95th percentile levels for PCB 114 were 0.039 μg/L plasma vs. 0.017 μg/L plasma. Linear regression models revealed that this difference in plasma levels was unequivocally attributed to the underground mining activity. Thus, retrospective exposure assessment for underground miners by use of human biomonitoring seems feasible and further studies with a particular focus on this special group of workers should be performed.