VOLATILE N-NITROSAMINE FORMATION AFTER INTAKE OF NITRATE AT THE ADI LEVEL IN COMBINATION WITH AN AMINE-RICH DIET

Formation of nitrite from ingested nitrate can result in several adver se health effects and implies a genotoxic risk as a consequence of end ogenous formation of carcinogenic N-nitroso compounds. We studied the formation of volatile N-nitrosamines after intake of nitrate at the ac ceptable daily intake (ADI) level in combination with a fish meal rich in amines as nitrosatable precursors. Twenty-five volunteers consumed this meal during 7 consecutive days; a diet low in nitrate was consum ed during 1 week before and 1 week after the test week. Nitrate intake at the ADI level resulted in a significant rise in mean salivary nitr ate and nitrite concentrations. Mean urinary nitrate excretion increas ed from 76 mg/24 hr in the first control week to 194 and 165 mg/24 hr in the test week, followed by a decline to 77 mg/24 hr in the second c ontrol week The urine samples were analyzed for volatile N-nitrosamine s, and both N-nitrosodimethylamine (NDMA) and N-nitrosopiperidine (NPI P) were detected in the samples. Mean urinary NDMA excretion significa ntly increased from 287 ng/24 hr in the control week to 871 and 640 ng /24 hr in the test week and declined to 383 ng/24 hr in the second con trol week Excretion of NPIP was not directly related to the nitrate in take and composition of the diet. Nitrate excretion and NDMA excretion were significantly correlated, as well as salivary nitrate and nitrit e concentration and NDMA excretion. We conclude that nitrate intake at the ADI level in combination with a fish meal containing nitrosatable precursors increases NDMA excretion in urine and thus demonstrates in creased formation of carcinogenic N-nitrosamines.