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| Volatile N-Nitrosamine Formation after Intake of Nitrate at the ADI Level in Combination with an Amine-rich Diet Ingrid T.M. Vermeer, Danielle M.F.A. Pachen, Jan W. Dallinga, Jos C.S. Kleinjans, and Jan M.S. van Maanen Department of Health Risk Analysis and Toxicology, Maastricht University, The Netherlands Abstract
Formation of nitrite from ingested nitrate can result in several adverse health effects and implies a genotoxic risk as a consequence of endogenous formation of carcinogenic N-nitroso compounds. We studied the formation of volatile N-nitrosamines after intake of nitrate at the acceptable 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 consumed 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 nitrate and nitrite concentrations. Mean urinary nitrate excretion increased 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 control week. The urine samples were analyzed for volatile N-nitrosamines, and both N-nitrosodimethylamine (NDMA) and N-nitrosopiperidine (NPIP) were detected in the samples. Mean urinary NDMA excretion significantly 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 control week. Excretion of NPIP was not directly related to the nitrate intake and composition of the diet. Nitrate excretion and NDMA excretion were significantly correlated, as well as salivary nitrate and nitrite 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 increased formation of carcinogenic N-nitrosamines. Key words: amines, nitrate, N-nitrosamines, N-nitrosodimethylamine. Environ Health Perspect 106:459-463 (1998) . [Online 1 July 1998] http://ehpnet1.niehs.nih.gov/docs/1998/106p459-463vermeer/ abstract.html Address correspondence to I.T.M. Vermeer, Department of Health Risk Analysis and Toxicology, Maastricht University, P.O.Box 616, 6200 MD, Maastricht, The Netherlands. This study was supported by the Netherlands Prevention Fund (grant 28-2844) . Received 17 December 1997 ; accepted 10 March 1998.
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