The levels of hydroxylated PCB metabolites in the concentrated sample extracts were quantified on an Agilent 7890A gas chromatograph with a 63Ni-micro electron capture detector (μECD) (Agilent, Santa Clara, California, USA) and an SPB-1 capillary column (60 m length, 250 μm inner diameter, 0.25 μm film thickness; Supelco, St Louis, MO, USA) using the internal standard method, as described.32 (link) OH-PCB levels, adjusted for the microsomal protein content, are presented in Table S2.