Induction of persistent hypersensitivity to lung tumorigenesis by in utero X-radiation in mice

A single dose (36 rad) of X rays was given to mouse embryos and neonates that were then treated with urethane at 21 days of age. Although in utero X-radiation to mice was not tumorigenic, it significantly increased lung tumor susceptibility to a postnatally-given carcinogen, urethane. X-ray induction of persistent hypersensitivity to lung tumorigenesis was apparent at all stages during days 0 to 14 of gestation (except on day 6), but was not observed at late fetal and neonatal stages.