Abstract
Certain nitroso compounds studied in hamsters have been found to cause tumors mainly in the respiratory tract (1). Diethylnitrosamine (DEN) also had a transplacental carcinogenic effect in hamsters (2). When the litters of treated and untreated mothers were exchanged, tumors were found only in the offspring of carcinogen-treated mothers nursed by untreated mothers. The offspring of untreated mothers nursed by mothers treated with carcinogen until the end of pregnancy showed no neoplastic alterations in the respiratory tract (3). We were able to show the presence of nitroso substances in the placenta and fetus of treated pregnant hamsters. Therefore, it was assumed that under these conditions, little or no carcinogen reached the young via the milk after delivery. In the experiments reported here, the effect on the young of carcinogen administered to mothers during lactation was studied.
Materials and Methods. In this set of experiments, 6-month-old hamsters were treated with high doses of DEN or dibutylnitrosamine (DBN) 1 to 30 days after delivery. Three groups of five animals received sc administrations of 5, 10, and 20 mg/kg of body weight of DEN dissolved in water. Three other groups received 300, 600, and 1200 mg/kg of body weight of DBN in olive oil (Table I).
Results. Nearly one-third of the offspring in the DEN groups died while nursing, showing acute toxic alterations in the liver and kidney. These changes were not observed in the DBN groups or in the controls. The experiments are still underway, with approximately 50% of the young still living more than 1 year after the treatment of their mothers.
Focal hyperplastic and dysplastic alterations of the mucosa in the trachea and nasal cavity were seen in treated mothers. All mothers also had tracheal papillary tumors.
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