Excretion of N-mononitrosopiperazine in urine in workers manufacturing piperazine.

Piperazine has been shown to nitrosate in vivo to N-mononitrosopiperazine (MNPZ) by oral intake. Urine from workers exposed to piperazine in a chemical plant was analysed for nitrosamines by gas chromatography-thermal energy analysis. In five out of 11 exposed cases, MNPZ excretion in urine was 0.3 to 4.7 micrograms/24 h (during and after a work shift). In four cases, MNPZ was detected in some urine samples, and in two cases MNPZ was not detected (less than 0.1 ng/ml). The individual excretion was strongly dependent on piperazine exposure, which ranged from 0.06 to 1.7 mg/m3 (time-weighted average; Spearman's rank correlation 0.78, P = 0.01). The MNPZ excretion showed no significant correlation with nitrite or nitrate in saliva (both: r = 0.50, P = 0.10).