Thirty-eight urinary samples (20-50 mL) were collected in glass containers, sealed and stored at -20oC before formaldehyde and acetaldehyde analyses by GC/FID [14]. All measured values were divided by urinary creatinine (Cr) concentration [15] for clinical chemistry analysis. The World Health Organization (WHO) has adopted guidelines for the acceptable limits of urinary creatinine concentrations between 0.3 and 3.0 g/L [5].