Lundgren D L, Hahn F F, Diel J H
Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico 87185.
Radiat Res. 1992 Dec;132(3):325-33.
Groups of 94-day-old F344/Crl rats were exposed repeatedly to aerosols of 144CeO2 to reestablish desired lung burdens of 1.9, 9.2, 46, or 230 kBq of 144Ce every 60 days for 1 year (seven exposures). Other 94-day-old rats were exposed once to achieve similar desired initial lung burdens of 144Ce. Older rats were exposed once to achieve desired initial lung burdens of 46 or 230 kBq when 500 days of age, the same age at which rats had the last of the repeated exposures. Control rats were either unexposed, sham-exposed once or repeatedly, or exposed once or repeatedly to stable CeO2. Approximately equal numbers of male and female rats were used. The median survival time and cumulative percentage survival curves were significantly decreased only in male and female rats exposed repeatedly to reestablish a 230-kBq lung burden and among the 94-day-old male rats exposed once to achieve a 230-kBq lung burden of 144Ce. The crude incidences of primary lung cancers (well described by a single Weibull distribution function), time to death with lung tumors, and risk of lung cancer per unit of beta-radiation dose to the lungs were correlated with the cumulative beta-radiation dose rather than the rate at which the dose was accumulated. A linear function, 70 (+/- 7.3) + -0.15 (+/- 0.056) x dose (+/- SD), adequately described the excess numbers of rats with lung cancers over a beta-radiation dose range to the lungs of 6.8 to 250 Gy for two groups of rats with the highest doses to the lungs after a single exposure and for two groups with the highest doses after repeated exposure.
将94日龄的F344/Crl大鼠分组，每60天重复暴露于144CeO2气溶胶中，持续1年（共7次暴露），以重新建立1.9、9.2、46或230 kBq的144Ce肺部负荷。其他94日龄的大鼠进行一次暴露，以达到类似的144Ce期望初始肺部负荷。年龄较大的大鼠在500日龄时进行一次暴露，以达到46或230 kBq的期望初始肺部负荷，这与大鼠最后一次重复暴露时的年龄相同。对照大鼠未暴露、进行一次或多次假暴露，或一次或多次暴露于稳定的CeO2。使用的雄性和雌性大鼠数量大致相等。仅在反复暴露以重新建立230 kBq肺部负荷的雄性和雌性大鼠以及一次暴露以达到230 kBq的144Ce肺部负荷的94日龄雄性大鼠中，中位生存时间和累积生存百分比曲线显著降低。原发性肺癌的粗发病率（由单一威布尔分布函数很好地描述）、因肺部肿瘤死亡的时间以及肺部每单位β辐射剂量的肺癌风险与累积β辐射剂量相关，而不是与剂量积累的速率相关。对于单次暴露后肺部剂量最高的两组大鼠和反复暴露后剂量最高的两组大鼠，线性函数70（±7.3）+-0.15（±0.056）×剂量（±标准差）充分描述了肺部β辐射剂量范围为6.8至250 Gy时肺癌大鼠的超额数量。
