Itm. Vermeer et al., VOLATILE N-NITROSAMINE FORMATION AFTER INTAKE OF NITRATE AT THE ADI LEVEL IN COMBINATION WITH AN AMINE-RICH DIET, Environmental health perspectives, 106(8), 1998, pp. 459-463
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.