“…The dose-response relationship was also suggested by the observation that the relative risk increased with increasing exposure. This observation confirms the evidence of previous studies concerning cigarette smoking (Bergström et al 1991, Haber & Kent 1992, Haber et al 1993, Grossi et al 1995, Bergström et al 2000a,b, Tomar & Asma 2000, Teng et al 2003, Baljoon et al 2004, 2005a, Bergström 2004, Razali et al 2005. This strength the association found in this cross sectional study.…”