An examination of human blood for the presence of volatile nitrosamines

Human blood was examined for the presence of volatile nitrosamines. Nitrosamines were detected by chemiluminescence and mass spectrometry after separation from blood by distillation and solvent extraction. N-nitrosodimethylamine was detected in all but one of 51 blood samples taken from 23 different people, at concentrations from the detection limit (0.1 microgram/litre) to 1.4 microgram/litre with a mean concentration of 0.5 microgram/litre. N-Nitrosodiethylamine was detected in 11 samples, the detection limit being 0.1 microgram/litre. No other volatile nitrosamines were detected. After a test meal of bacon, spinach, bread and beer, the concentration of N-nitrosodimethylamine increased. There was no appreciable difference between the nitrosamine concentrations in the blood of laboratory workers and in the blood of other people. Salivary nitrite concentrations measured semi-quantitatively concurrently with blood sampling varied considerably but showed no apparent correlation with blood nitrosamine levels. Measurements in rabbits given a continuous infusion of N-nitrosodimethylamine gave a clearance rate approximately equal to the blood flow through the liver and a volume of distribution of 1.2 litre/kg body weight. By applying these results to man, the body burden after the meal was calculated as 40-50 microgram. This is substantially higher than the estimated weekly intake of volatile nitrosamines from food.