Acute and late effects of tritium beta particles on rats exposed to tritiated water as infants.

Lethality and physiological disorders induced by tritium beta particles were studied in rats. Newborn CD/Crj rats received i.p. HTO saline at 0, 8.14, 16.28, 24.42 and 32.56 MBq/g body weight (BW). At four weeks of age, HTO over 24.42 MBq/g BW was fatal, especially in male rats, but it was not obvious under 16.28 MBq/g BW. Surviving female rats were weaned at four weeks of age and rats were monitored for heart rate and blood pressure (systolic, mean and diastolic) at 13, 23 and 30 weeks of age and sacrificed. The blood pressure significantly increased with the administered doses of HTO. Sclerotic kidneys were frequently observed in hypertensive rats exposed to HTO over 24.42 MBq/g BW. Thickened intermediate layer of artery, infiltrating lymphocytes and atrophic mesangiums were observed in sclerotic kidneys. These results indicate that internal exposure to HTO as infants was induced consequent hypertension in association with sclerotic kidney at sublethal doses.