Hospital waste incinerator workers are exposed to various pyrolysis products including polycyclic aromatic hydrocarbons (PAHs). We evaluated their exposure by assessing urinary 1-hydroxypyrene glucuronide (1-OHPG), as an internal dose of PAH exposure. The potential effect of genetic polymorphisms of GSTM1/T1 involved in PAH metabolisms was also investigated. Pre- and post-shift samples were collected from 28 hospital incinerator workers. Urinary 1-OHPG was assayed by synchronous fluorescence spectroscopy (SFS) after immunoaffinity purification with the monoclonal antibody 8E11. Genotypes of GSTM1/T1 were assessed by PCR-based methods. Information on smoking habits and use of personal protective equipment were collected by means of a self-administered questionnaire. The Mann-Whitney test was used to compare group means of these biomarkers. Urinary 1-OHPG levels were similar in pre- and post-shift urine samples. The arithmetic mean concentrations of urinary 1-OHPG were 0.16 +/- 0.04 micromol/mol creatinine pre-shift and 0.19 +/- 0.09 micromol/mol creatinine post-shift, but urinary 1-OHPG levels were significantly higher in individuals with the GSTM1 null genotype than with the GSTM1 present genotype (p=0.05, by Mann-Whitney test). Our results suggest that the urinary 1-OHPG levels in hospital waste incinerator workers may be modified by the GSTM1 genotype, but these findings remain to be confirmed in future studies involving larger sample sizes.