Abstract: Both expo su re and effect b iom arkersw ere m easu red in residen t s ofW ilrijk and Hoboken, indu st rial subu rb s of the b ig city of A n tw erp , and in residen t s of Peer, a ru ralm un icipality w ith in ten sive agricu ltu re (14, 622 inha2 b itan t s, 70 km east ofA n tw erp ). Person sw ith know n occupat ional expo su res, o rwo rk ing in a region w ith po l2 lu t ion levels clearly differen t f rom the area of residence o r comm u t ing over long distances, w ere excluded f rom the study. Here w e repo rt the HPRT varian t f requencies fo r 98 healthy non2smok ing wom en aged 50265 (46 f rom Peer, 29 f rom Hoboken and 23 f rom W ilrijk). The HPRT varian t f requency (V F) , determ ined u sing im2 m unocytochem ical stain ing w ith monoclonal an t i2B rdU , w as (m ean±s. d. ) 4. 8×10- 6±3. 5×10- 6 fo rW ilrijk, 13. 6×10- 6±31. 2×10- 6 fo r Hoboken and 19. 7×10- 6±49. 8×10- 6 fo r Peer. Fo r the to tal study popu lat ion, there w as no sign if ican t co rrelat ion (neither in a simp le linear regression no r in a stepw ise m u lt ip le regression w ith F to include= 1 and F to exclude= 0. 8) of V F w ith the fo llow ing personal o r life2style param eters: age, body m ass index, num ber of p regnancies, num ber of mon th s du ring w h ich b reast feeding w as given, con sump2 t ion ofm eat, of f ish, of baked o r grilledm eat o r f ish, of smoked o r salted m eat o r f ish, of o rgan icm eat o rm u s2 sels o r sh rimp s, of dairy p roduct s, daily in take of ethano l, of an im al fat, of calcium. A ncova analysis show ed that V F w as sign if ican t ly h igher in Peer than inW ilrijk af ter co rrect ion fo r age, fo rm er smok ing and level of ed2 ucat ion (P = 0. 0142).