The concentration of selected cancer markers (TPA, TPS, CYFRA 21-1, CEA) in workers occupationally exposed to arsenic (As) and some heavy metals (Pb, Cd) during a two-year observation study - Szymańska-Chabowska, Anna; Antonowicz-Juchniewicz, Jolanta; Andrzejak, Ryszard (Instytut Medycyny Pracy w Łodzi im. prof. J. Nofera)