Effects of N-nitrosopyrrolidine, nitrite and pyrrolidine on tumour development in mice as related to ingestion of cured meat

Abstract

The incidence of tumours in mice fed a standard chow diet and given either N-nitrosopyrrolidine (NPyr), nitrite (NO 2) or nitrite plus pyrrolidine (NO 2 + Pyr) in the drinking water for 12 months at 100mg, 1 g and 1 g plus 100mg/litre, respectively, was compared with that for a control group (C) receiving no additives. Differences between groups in weight gain and feed consumption were not significant. Group 3 (NO 2) drank less water ( P < 0·05) than those in groups 1 (C) and 2 (NPyr). Water intake of mice in group 4 (NO 2 + Pyr) did not differ from that of any of the other three groups. Survival rates were: 94% (C), 80% (NPyr), 92% (NO 2) and 83% (NO 2 + Pyr); but the differences were not statistically significant. Gross examination upon autopsy revealed that the incidence of all tumours in group 2 (NPyr) was 10- to 20-fold higher than that in any other group. Histological examination confirmed that NPyr induced more ( P < 0.05) malignant tumours in liver and lungs with any other treatment; otherwise there were no significant differences. Results indicated that NO 2 + Pyr (nitrite plus a secondary amine) did not increase the frequency of carcinogenic tumours in mice.