High level of tritium-remaining in brain of rats exposed to tritiated water as infants.

Newborn CD/Crj rats were given tritiated water (HTO) saline i.p. at the dose of 220 microCi (8.14 MBq)/g of B.W. We monitored residual tritium in the sera and organs of male rats up to 26 weeks of age. The total absorbed doses in serum, liver, spleen, testis and brain were estimated to be 3.10, 2.35, 2.43, 2.38 and 2.84 Gy, respectively. Over four weeks of age, a 3-19 times higher tritium content was noted in brain compared to the values of other organs. At 26 weeks of age, testis atrophy was predominant with 20% of control value by relative organ weight in association with decreased spermatogonia and increased Leydig cells. The serum testosterone level was 67% and relative adrenal weight was significantly increased in comparison with the control values. The results indicated that the high accumulation of tritium in brain, destruction of spermatogenesis and feedback of androgenic response were caused by exposure to HTO as infants.