A CROSS-SECTIONAL OBSERVATION OF THE HEALTH-EFFECTS OF HYDRAZINE HYDRATE AND DIFFERENCES OF ITS METABOLISM BY NAT2 POLYMORPHISM

Objectives: To summarize the results of two studies that attempted to clarify: (1) the health effects of hydrazine hydrate (HH) (N2H4 . H2O: CAS No. 7803-57-8); and (2) the influence of allelic polymorphism of N-acetyltransferase (NAT2) on the metabolism of HH. Methods: A cross-s ectional survey was carried out on 172 male HH-exposed workers and 125 male referent workers at five factories in Japan. The biological half -lives of HH after 1 h of exposure were determined in 12 workers, four workers in each of three NAT2 phenotypes. Clinical examinations were performed and acute and chronic subjective symptoms related to HH were examined by self-administered questionnaires. NAT2 phenotypes were as sessed. Results: No hydrazine was detected in either the breathing zon es or the urine of the referent workers. The mean hydrazine concentrat ion in the breathing zones, hydrazine and acetylhydrazine in urine, an d the cumulative exposure level were 0.0109 ppm, 0.8660 mu mol/g . Cr, and 2.80 ppm-years, respectively. There was no difference and no dose -dependent change in the health examination items between HH-exposed a nd referent workers after adjusting confounding factors, nor in terms of the differences of NAT2 phenotypes. Of 90 subjective symptoms, comp laints of nightmares were significantly related to HH exposure. The ha lf-life of urinary hydrazine and acetylhydrazine on rapid, intermediat e, and slow phenotypes was 1.68, 3.01, and 4.46 h, respectively. Concl usion: This study suggested that current and cumulative exposure to HH did not affect the workers' health, and the half-life of the slow phe notype was longer than those of the rapid and intermediate phenotypes.