Transplacental carcinogenesis and chemical determination of 1-butyl-1-nitrosourea in stomach content after simultaneous oral administration of 1-butylurea and sodium nitrite to ACI/N rats.

Solutions of 100 mg/kg 1-butylurea and 50 mg/kg sodium nitrite were administered daily by a stomach tube to pregnant ACI/N rats from the 13th to 21st day of gestation. Neurogenous tumors were induced in their offspring. The incidence of tumours and mean survival time of rats with nervous tumours were 64% (23/36) and 309 (189672) days respectively. Localization and histological findings of the nervous tumors were similar to those observed previously in rats whose mothers received 1-butyl-1-nitrosourea (BNU) during pregnancy. Neurogenous tumors did not develop in the offspring of the mothers that received 100 mg/kg of 1-butylurea alone in the same manner. In several rats of both group, a few spontaneous tumors of the testis, pituitary gland, urinary bladder, uterus, and colon were detected. In vivo formation BNU in stomach content after intubation of 1-butylurea and sodium nitrite was determined. BNU was detected in the stomach content at levels of 25 ppm at 30 min and 23 ppm at 60 min after administration. The concentration of BNU in the stomach content corresponded to 48.3 and 29.2 microng/rat, respectively.