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EC number: 209-935-0 | CAS number: 598-50-5
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Guinea-pigs were treated with methylurea (MU) and sodium nitrite and the formation of N-nitrosomethylurea (NMU) from MU and sodium nitrite and the disappearance of NMU was analysed in the stomach. NMU was shown to be formed readily in the stomach of the guinea-pig and to be absorbed from the stomach into the blood (Yamamoto et al., 1987).
Key value for chemical safety assessment
Additional information
In the study of Yamamoto et al., 1987, guinea-pigs were treated with methylurea (MU) and sodium nitrite. The study was concentrated on the formation of N-nitrosomethylurea (NMU) from MU and sodium nitrite in the guinea-pig stomach and the disappearance of NMU from the stomach. Guinea-pigs were used since they have only glandular stomachs and the pH of the gastric juice (1-2) is similar to that of humans. NMU was relatively stable in the isolated gastric contents of this species. When NMU was injected into the pylorus-ligated stomach of fasting guinea-pigs, about 50 and 37% of the NMU remained at 20 and 30 min, respectively. Some 19 and 42% remained 30 min after NMU was given orally by stomach tube to fasting and feeding guinea-pigs, respectively. NMU was detected in most blood samples irrespective of the administration procedure, but it disappeared rapidly from the blood after i.v. injection. Nitrite disappeared rapidly from the pylorus-ligated stomach, residual nitrite being less than 20% of the dose in 2.5 min. When 7.5 µmol MU and 15 µmol NaNO2 were co-injected into the ligated stomach, 3.1 µmol NMU was detected 10 min after the injection, followed by a gradual decrease. When MU and NaNO2 were given orally to the animals, 0.7-1.0 µmol NMU was detected in the stomach 10 min after the treatment. Thus NMU was shown to be formed readily in the stomach of the guinea-pig and to be absorbed from the stomach into the blood.
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