Identification and quantitative determination of aniline and toluidines in human urine.

Aniline and o-, m-, and p-toluidine, which are representative of aromatic amines in cigarette smoke, were identified and quantified in human urine. Smokers excreted 3.1 +/- 2.6 micrograms/24 h of aniline and 6.3 +/- 3.7 micrograms/24 h of o-toluidine (n = 16). Nonsmokers excreted 2.8 +/- 2.5 micrograms/24 h of aniline and 4.1 +/- 3.2 micrograms/24 h of o-toluidine (n = 12). Meta- and p-toluidine were detected in the urine of 2 of 11 smokers and 4 of 9 nonsmokers. The observed intra- and interindividual variations in the amounts of urinary aniline and o-toluidine were relatively large. The results of this study demonstrate for the first time that aniline and toluidines are present in human urine and suggest that sources other than cigarette smoke contribute significantly to their concentrations in urine.