A screening study has been performed concerning bis(4-Chlorophenyl) sulfone (BCPS). BCPS is a high production volume chemical and is mainly used in the polymer production. It has been detected in biota in several species from the Baltic Sea environment but the source for its detection is unknown. Air, deposition, sediment, fish, effluent and surface were sampled mainly from the Baltic sea region. BCPS was present in all fish samples (perch and herring) and in similar levels as PCB 138 and PCB 153. There was no trend in concentrations between species, country or sampling location. BCPS was detected in all three marine surface samples which may explain the bioaccumulation in biota. It was detected in one air sample in the same magnitude as individual PCB congeners and in one of the WWTP samples. This screening did not clarify the pathways of BCPS to the Baltic Sea. However, the results indicate that distribution is more waterborne rather than airborne