Associations between plasma concentrations of PCB 28 and possible indoor exposure sources in Danish school children and mothers.

•The plasma PCB 28 in children is significantly associated with living in homes constructed in the PCB period of 1950-1977.•The PCB 28 in Danish school children is significantly associated with attending schools constructed or refurbished in the PCB period.•The plasma concentration of PCB 28 found in the Danish families was in line with concentrations in other European countries.•The indoor exposure from schools seems to contribute significantly to the exposure to PCB 28 in children.