despite the relatively low levels of exposure. Additionally, t,t-muconic acid levels in urine samples collected in the afternoon, and 1- OHP levels in samples collected the following morning, did show a statistically significant correlation with per- sonal exposures to benzene and PAHs, respectively. This would seem to indicate that these are useful biomarkers of exposure, particularly since they are alsonon-invasive. However, only DNA adducts are generally accepted as being predictive of health effects, such as cancer (Vineis and Perera, 2000; Rundle et al., 2000).