Assessment of a potential PCB exposure among (former) underground miners by hydraulic fluids.

Polychlorinated biphenyls (PCBs) were used in technical mixtures of different PCB congeners as hydraulic fluids in underground mining in Germany in North Rhine-Westphalia, Ibbenbueren, and Saarland from the mid-1960s to 1986. Mine workers who were involved in maintenance and repair or operation of hydraulically driven machines in underground mines were potentially exposed to liquids containing PCBs. The aim of the present study was to investigate whether this potential exposure which occurred more than 30 years ago was still detectable. Biomonitoring and a structured work anamnesis were conducted on a representative sample of 210 miners. PCBs in plasma were measured by gas chromatography coupled to mass spectrometry with an LOQ of 0.01 µg/L plasma for all congeners. The primary aim was comparison of the number of exceedances of the underlying comparative values for PCB congeners with those of the general population. Secondary endpoint was the question whether there were regional differences in potential PCB exposure. The biomonitoring showed a significant difference for PCB 74 with N= 94 (45%); for PCB 114 with N = 64 (31%) and for PCB 99 and PCB 105 with N = 23 (11%) and N = 19 (9%) of 210 measurements above the reference value compared to the general population (5%). The all over detection frequencies (µg/L plasma median | SD | min |max) of these congeners were as follows:PCB 74: 0.128 | 0.481 | < LOD | 3.098; PCB 99:0.035 | 0.078 | < LOD | 0.582PCB 105: 0.005 | 0.031 | < LOD | 0.307; PCB 114:0.005 | 0.024 | < LOD | 0.140Regional differences were not detectable.