© 1987 Oxford University Press
research-article |
Transfer of the tobacco-specific carcinogens N'-nitrosonornicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo [a] into the milk of lactating rats
American Health Foundation, Naylor Dana Institute for Disease Prevention Valhalla, NY 10595, USA
The extent to which some of the more prevalent and potent carcinogens in cigarette smoke could be transferred from circulating blood into the milk of lactating rats was determined. One hour after i.v. administration of benzo[a]pyrene (BaP), N'-nitrosonornicotine (NNN) and 4-(methylnitros-amino)-1-(3-pyridyl)-1-butanone (NNK) to the dams, the levels of these carcinogens were determined in both blood and milk specimens. The average amount of radioactivity detected 1 h after administration of 14C BaP was 0.21% of the administered dose per ml of milk as compared with 0.17% per ml of blood. The amount of NNN in milk ranged from 0.20 to 0.36% of the administered dose per ml which closely paralleled the levels detected in blood. NNK is readily con verted in vivo to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). The sum of NNK and NNAL was similar in the blood and milk of treated dams. There was, however, a major difference in the ratio of NNAL/NNK as detected in milk and blood. The ratio of NNAL/NNK in blood ranged from 1.3:1 to 1.9:1 while the ratio in milk ranged from 2.4:1 to 3.3:1. In a comparative study of the levels of NNN in the blood and milk of lactating rats at <1.0, 20, 60, 120 and 240 mm after administration, it was confirmed that similar concentrations of NNN are present in blood and milk 1 h after administration. These data indicate that these carcinogens, which are present in both cigarette smoke and tobacco, can be transferred into the milk of lactating rats.