Biological effects of inhaled 238PuO2 in beagles.

Beagle dogs exposed to 238PuO2 aerosols (136 dogs, 13-22 per group, mean initial lung depositions of 0.0, 0.13, 0.68, 3.1, 13, 52 and 210 kBq) were observed throughout life to determine tissues at risk and dose-effect relationships. The pulmonary retention of 238Pu was represented by the sum of two exponentially decreasing components of the initial lung deposition; about 84% cleared with a 174-day half-time; the half-time of the remainder was 908 days. The average percentages of final body burden found in lung, skeleton, liver and thoracic lymph nodes in the 30 longest-surviving dogs (mean survival 14 years) were 1, 46, 42 and 6%, respectively. Of 116 beagles exposed to plutonium, 34 (29%) developed bone tumors, 31 (27%) developed lung tumors, and 8 (7%) developed liver tumors. Although lungs accumulated a higher average radiation dose than skeleton, more deaths were due to bone tumors than to lung tumors. Deterministic effects included radiation pneumonitis, osteodystrophy, hepatic nodular hyperplasia, lymphopenia, neutropenia and sclerosing tracheobronchial lymphadenitis. Hypoadrenocorticism was also observed in a few dogs. Increased serum alanine aminotransferase, indicative of liver damage, was observed in groups with > or =3.1 kBq initial lung deposition. Estimates of cumulative tissue dose in a human exposed to airborne 238PuO2 for 50 years at a rate of one annual limit on intake each year were derived based on a comparison of the data on metabolism for humans and beagles. The 50-year dose estimates for humans are an order of magnitude lower than doses at which increased incidence of neoplasia was observed in these dogs, whereas the projected doses to humans from 50-year exposure at the annual limit of intake are of similar magnitude to those at which deterministic effects were seen in the beagles.

Reproduction of the owl monkey (Aotus spp.) in captivity.

The reproduction performance of captive owl monkeys, a breed used extensively in biomedical research, was observed at the Battelle Primate Facility (BPF). The colony grew through captive breeding, imports from the Peruvian Primatological Project, and others to a peak size of 730. It included seven karyotypes of Aotus sp. Results showed that owl monkeys can breed successfully in a laboratory in numbers sufficient to sustain modest research programs. Reproductive success increases when pairs are compatible, of the same karyotype, and stabilized; however, mated pairs of different karyotype are also productive. Under conditions of controlled lighting and heating, owl monkeys at BPF showed no birth peak nor birth season.

Hypoadrenocorticism in beagles exposed to aerosols of plutonium-238 dioxide by inhalation.

Hypoadrenocorticism, known as Addison's disease in humans, was diagnosed in six beagles after inhalation of at least 1.7 kBq/g lung of 238PuO2. Histological examination of adrenal gland specimens obtained at necropsy revealed marked adrenal cortical atrophy in all cases. Autoradiographs showed only slight alpha-particle activity. Although the pathogenesis of adrenal cortical atrophy in these dogs is unclear, there is evidence to suggest an autoimmune disorder linked to damage resulting from alpha-particle irradiation to the lymphatic system.

The distribution and effects of inhaled 239Pu(NO3)4 deposited in the liver of dogs.

The distribution and effects of inhaled 239Pu(NO3)4 deposited in the liver of dogs were studied in five groups of 20 beagles exposed to initial lung depositions ranging from 1.0 to 520 Bq g(-1) lung. Following life-span observations, the liver contained 40 +/- 1% of the final body deposition of plutonium, second only to the skeleton. The liver-to-skeleton ratio of deposited plutonium for total organ was 0.8, or 3.5 when expressed on a per-gram basis. There was no effect of exposure level on liver-to-skeleton ratios. Autoradiographs showed that the dose rate delivered to parenchymal cells was higher than evident from radiochemical analysis of the whole organ. Elevated levels of serum liver enzymes were observed in groups with mean liver concentrations of 1.3 Bq g(-1) and liver doses of 3 Gy or higher. Nodular hyperplasia of liver and bile-duct hyperplasia were observed. Liver tumors, principally of bile-duct epithelium, were late-occurring and were observed at lower exposure levels at which life span was not shortened by lung or bone tumors.

Clastogenic effects of defined numbers of 3.2 MeV alpha particles on individual CHO-K1 cells.

Research to determine the effects of defined numbers of alpha particles on individual mammalian cells is helpful in understanding risks associated with exposure to radon. This paper reports the first biological data generated using the single-particle/single-cell irradiation system developed at Pacific Northwest Laboratory. Using this apparatus, CHO-K1 cells were exposed to controlled numbers of 3.2 MeV alpha particles, and biological responses of individual cells to these irradiations were quantified. Chromosomal damage, measured by the induction of micronuclei, was evaluated after no, one, two, three or five particle traversals. Exposures of up to five alpha particles had no influence on the total numbers of cells recovered for scoring. With increased numbers of alpha particles there was a decrease in the ratio of binucleated to mononucleated cells of 3.5%/hit, suggesting that alpha particles induced dose-dependent mitotic delay. A linear hit-response relationship was observed for micronucleus induction: Micronuclei/binucleated cell = 0.013 +/- 0.036 + (0.08 +/- 0.013) x D, where D is the number of particles. When the estimated dose per alpha-particle traversal was related to the frequency of induced micronuclei, the amount of chromosomal damage per unit dose was found to be similar to that resulting from exposures to alpha particles from other types of sources. Approximately 72% of the cells exposed to five alpha particles yield no micronuclei, suggesting the potential for differential sensitivity in the cell population. Additional studies are needed to control biological variables such as stage of the cell cycle and physical parameters to ensure that each cell scored received the same number of nuclear traversals.

Magnetic field characteristics of electric bed-heating devices.

Measurements of the flux density and spectra of magnetic fields (MFs) generated by several types of electric bed heaters (EBH) were made in order to characterize the MFs to which the fetus may be exposed in utero from the mother's use of these devices. Data on MPs were gathered from more than 1,300 in-home and laboratory spot measurements. In-home measurements taken at seven different positions 10 cm from the EBHs determined that the mean flux density at the estimated position of the fetus relative to the device was 0.45 microT (4.5 mG) for electric blankets and 0.20 microT (2.0 mG) for electrically heated water beds. A rate-of-change (RC) metric applied to the nighttime segment of 24 h EMDEX-C personal-dosimeter measurements, which were taken next to the bed of volunteers, yielded an approximate fourfold to sixfold higher value for electric blanket users compared to water-bed heater users. These same data records yielded an approximate twofold difference for the same measurements when evaluated by the time-weighted-average (TWA)MF exposure metric. Performance of exposure meters was checked against standard fields generated in the laboratory, and studies of sources of variance in the in-home measurement protocols were carried out. Spectral measurements showed that the EBH's measured produced no appreciable high-frequency MFs. Data gathered during this work will be used in interpreting results from a component of the California Pregnancy Outcome Study, which evaluates the use of EBHs as a possible risk factor in miscarriage.

Serum and urine biochemical diversity among adult wild-caught Aotus nancymae and Saimiri peruviensis.

Serum and urine analytes were compared between adult wild-caught owl monkeys (Aotus nancymae) and adult wild-caught squirrel monkeys (Saimiri peruviensis) to determine if normative clinical pathology data were similar. An objective of the study was to confirm that species of neotropical primates are distinct with regard to physiologic parameters, and should not be considered interchangeable in biomedical research. Significant differences (P < 0.05) were noted in many serum and urine analytes between the two groups. The results suggest that reference data for wild-caught owl monkeys are not applicable to squirrel monkeys, and the differences are sufficiently large to be of clinical significance. These findings illuminate the diversity among species of neotropical primates.

The role of dose rate in the induction of micronuclei in deep-lung fibroblasts in vivo after exposure to cobalt-60 gamma rays.

To evaluate the influence of low-dose-rate exposures on biological damage, it is necessary to have cells that can be maintained in the same stage of the cell cycle for long periods. Normal rat lung fibroblasts represent a stable cell type with a slow turnover rate in vivo. These cells can be stimulated to divide by placing them in tissue culture. Therefore, a constant cell population can be exposed over a protracted time and stimulated to divide, and the cytogenetic damage can be evaluated at the first cell division after exposure. By placing rats at different distances from a 60Co source, they were exposed to graded doses of gamma rays--0.0, 3.9, 7.4 and 11.3 Gy--protracted over either 4 or 67 h. Fibroblasts were isolated from the lung and cultured for 24 h; after cytochalasin B was added, the cells were cultured for an additional 69 to 72 h. The percentage binucleated cells in fibroblasts of animals exposed for 4 or 67 h was 47.1 +/- 4.3 and 62.1 +/- 3.9. There was no influence of dose on the percentage binucleated cells, but the fraction of cells that divided at 67 h was significantly higher (P < 0.05) than observed at 4 h. Cells were scored for micronuclei on coded slides. The dose-response data from animals exposed for 4 and 67 h were fitted to the following linear dose-response relationships, where D = dose; micronuclei/binucleated cell = 0.02 +/- 0.03 + 2.38 +/- 0.44 x 10(-2) D, and micronuclei/binucleated cell = 0.01 +/- 0.06 + 1.01 +/- 0.10 x 10(-2) D, respectively. The r2 values for the two curves were 0.67 and 0.91, indicating the goodness of fit for the data for the 4- and 67-h treatments. The slopes were different from zero and each other at the P < 0.05 level of significance. The effectiveness of the 60Co exposure decreased as the dose rate decreased. At dose rates below 0.17 Gy/h, the effectiveness remained constant over the range of doses and dose rates used. Comparing the slope of the dose response for the lowest exposure rate to that from information published previously, the dose-rate effectiveness factor was 6.14 +/- 0.65 for the induction of micronuclei in deep-lung fibroblasts.(ABSTRACT TRUNCATED AT 400 WORDS)

Hepatic effects of inhaled plutonium dioxide in beagles.

The effects of inhaled 238PuO2 deposited in the liver of dogs were studied in beagles exposed to initial lung depositions ranging from 5.7 to 2979.7 Bq/g lung. Approximately 20% of the initial lung deposition was translocated to the liver by 1500 days after exposure. Life-span observations revealed that the liver contained 40% of the final body burden of plutonium, second only to the skeleton. Elevated serum liver enzyme activities were observed in dogs with final liver depositions of > or = 0.4 Bq/g, cumulative dose to the liver of > or = 0.18 Gy and annual dose rate > or = 0.02 Gy/year. Enzyme elevations were seen at one dose level lower than that in which bone or lung tumors were observed. Linear regression analysis revealed strong to moderate correlation between cumulative dose and dose rate and time to observed increases in liver enzyme activities. Liver tumors were late-occurring neoplasms observed at lower exposure levels where life span was not shortened by lung and bone tumors.

Hematologic values of the wild-caught karyotype V owl monkey (Aotus vociferans).

Blood samples from 35 wild-caught owl monkeys (Aotus vociferans, karyotype V) were analyzed to estimate reference intervals of hematologic variables for the species. Findings indicated that distributions were abnormal for leukocytes, neutrophils, eosinophils, basophils, and monocytes. Statistically significant sex differences, too small to be of clinical importance, were found in values for mean cell hemoglobin concentration, leukocytes, and basophils. Reference intervals for the hematologic variables were calculated by the nonparametric percentile estimation method. Comparison of hematologic reference values for wild-caught A. vociferans with those of A. nancymae revealed statistically significant differences for packed cell volume, mean cell volume, leukocytes, eosinophils, basophils, and platelets. These differences also appeared too small to be of clinical significance.

Examination of testicular tumours in the beagle dog exposed to inhaled plutonium.

Gross and light microscopic features of testicular neoplasms were examined in the male beagle dog used in three studies to examine the life-span effects of inhaled plutonium (Pu). One hundred and sixty-six cases of testicular neoplasia (TN) occurred among 105 dogs that ranged in age from 7.5 to 17.7 years at the time of diagnosis. The 166 cases of TN comprised 113 interstitial cell tumours, 27 seminomas in situ, 19 seminomas, and seven Sertoli cell tumours. Serum testosterone and estradiol 17-beta concentrations, and the serum testosterone-to-oestradiol ratio were determined in 39 dogs with TN and in five clinically normal, sexually intact, age-matched cohorts. Serum hormone concentrations did not differ significantly among tumour types or between dogs with neoplasms and age-matched cohorts. There was a significant relationship between initial lung deposition (ILD) of Pu and activity in the testis (Bq/g testis). The slope of the relationship was 0.35, 0.89 and 0.91 for 239PuO2, 238PuO2 and 239Pu(NO3)4 respectively. Pu in the testis at long times (> 5 years) after inhalation was between 0.0001 and 0.03% ILD, depending on the physicochemical form of Pu. Although the mean activity of Pu in the testis of dogs was higher in those life-span studies employing 238PuO2 and 239Pu(NO3)4, the cumulative proportion of dogs with tumours, the distribution of tumour types, and mean time to first tumour was not significantly different among the three studies or dose groups, including controls, within a study.

Hematological effects of inhaled plutonium dioxide in beagles.

A life-span study indicated that plutonium activity in the thoracic lymph nodes is a contributor to development of lymphopenia in beagles exposed to 239PuO2. Significant lymphopenia was found in 67 (58%) beagles given a single nose-only exposure to 239PuO2 to result in mean initial lung depositions ranging from 0.69 to 213.3 kBq. Lymphoid atrophy and sclerosis of the thoracic lymph nodes and lymphopenia were observed in exposure-level groups with initial lung depositions > or = 2.5 kBq. Those dogs with final plutonium concentrations in the thoracic lymph nodes > or = 0.4 kBq/g and dose rates > or = 0.01 Gy/day developed lymphopenia. Marked differences existed between chronically lymphopenic dogs and intermittently lymphopenic dogs with regard to initial lung deposition, time to lymphopenic events and absolute lymphocyte concentrations. Linear regression analysis revealed moderate correlation between reduction in lymphocyte values and initial lung deposition, in both magnitude and time of appearance after exposure. Cumulative dose and dose rate appeared to act together to produce initial effects on lymphocyte populations, while dose rate alone appeared to be responsible for the maintenance and subsequent cycles of lymphopenia seen over the life span. No primary tumors were associated with the thoracic lymph nodes in this study, although 70% of the lymphopenic dogs developed lung tumors.

Inhaled radon-induced genotoxicity in Wistar rat, Syrian hamster, and Chinese hamster deep-lung fibroblasts in vivo.

This study was performed (1) to provide a comparison of the genotoxic effects of inhaled radon and radon progeny, referred to as radon in this paper, among three species of rodents: Wistar rats, Syrian hamsters, and Chinese hamsters; (2) to determine if initial chromosome damage was related to the risk of induction of lung cancer; and (3) to evaluate the tissue repair and long-term presence of cytogenetic damage in respiratory tract cells. These species were selected because Syrian hamsters are very resistant to radon induction of lung cancer and Wistar rats are sensitive; no literature is available on the in vivo effects of radon in the Chinese hamster. Exposure-response relationships were established for the rats and Syrian hamsters while the Chinese hamsters received a single exposure of radon. At 4 h (0.2 days), 15 days, and 30 days after the highest WLM exposure to radon, Wistar rats, Chinese hamsters, and Syrian hamsters were killed, and lung fibroblasts were isolated and grown in culture to determine the frequency of induced micronuclei. Animals at each level of exposure showed an increase in the frequency of micronuclei relative to that in controls (P < 0.05). The exposure-response relationship data for rats and Syrian hamsters killed 0.2 days after the end of exposure were fit to linear equations (micronuclei/1000 binucleated cells = 15.5 +/- 14.4 + 0.53 +/- 0.06 WLM and 38.3 +/- 15.1 + 0.80 +/- 0.08 WLM, respectively). For the single exposure level used (496 WLM) in Chinese hamsters killed at 0.2 days after exposure, the frequency of micronuclei/1000 binucleated cells/WLM was 1.83 +/- 0.02. A comparison of the sensitivity for induction of micronuclei/WLM illustrated that Chinese hamsters were three times more sensitive than rats. The Syrian hamsters also showed a significantly elevated response (P < 0.05) relative to rats. These data suggest that initial chromosome damage is not the major factor responsible for the high rate of radon-induced cancer in rats relative to Syrian hamsters. The frequency of micronuclei in radon-exposed rats, Syrian hamsters, and Chinese hamsters significantly decreased (P < 0.05) as a function of time after the exposure. The rate of loss of damaged cells from the lung was greatest in the Chinese hamsters, followed by Wistar rats and Syrian hamsters, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Comet assay reveals DNA strand breaks induced by ultrasonic cavitation in vitro.

The induction of DNA strand breaks in cultured Chinese hamster ovary (CHO) cells was investigated in suspensions directly exposed to 2.17-MHz ultrasound. Production of hydrogen peroxide, a DNA-damaging sonochemical, by inertial cavitation was enhanced by the use of argon-and-oxygen-bubbled media and cell survival was improved by establishing standing waves and minimizing tube rotation. Viable cells were separated from the suspension after exposure and kept on ice for evaluation with the single-cell gel electrophoresis (comet) assay. With this assay, DNA damage from as little as 2-mumol/L hydrogen peroxide treatment for 30 min could be detected, and cell survival as low as 2-5% after ultrasound exposure was adequate for assay. An ultrasound dose-response trend was noted for increasing pressure amplitude up to 0.82 MPa (free field) and increasing exposure duration up to 4 min. The cells were able to repair some of the strand breaks when warmed to 28 degrees C for 30 min. The effect was not eliminated by addition of catalase, which indicates that the DNA damage was not due to the action of residual H2O2 alone. The results confirm the hypothesis of DNA damage in cells surviving inertial cavitation.

Effectiveness of radon relative to acute 60Co gamma-rays for induction of micronuclei in vitro and in vivo.

Because radon and its progeny (referred to collectively here as radon) emit alpha particles with a wide range of energies, as well as beta particles and gamma-rays, it is important to quantitate the relationship between initial damage induced by radon and that by acute low-LET radiation. We have evaluated dose-response relationships for induction of micronuclei both in vivo and in vitro following exposure to radon or 60Co. To determine if isolation procedures altered the cells' responsiveness to 60Co gamma-ray exposures, animals were exposed before cell isolation, or cells were isolated and then exposed. The data were described by linear dose-response functions and were not significantly different when the radiation exposure was in vivo or in vitro (respectively micronuclei/1000 binucleated cells = 1.6 +/- 6.5 + 62 +/- 2.7 D; micronuclei/1000 binucleated cells = 15.4 +/- 26.0 + 54.6 +/- 11.4 D, where D is in Gy). Primary rat lung fibroblasts (RLF) or Chinese hamster ovary (CHO-K1) cells were exposed in vitro to either radon or 60Co gamma-rays. Radon was 10.9 +/- 2.6 and 12.5 +/- 2.4 times as effective per Gy of radiation dose in producing micronuclei as was 60Co in RLF and CHO-K1 cells respectively. To determine the relative biological effectiveness of in vivo radon exposure, animals were exposed to either radon or 60Co, and lung fibroblasts were isolated and evaluated for radiation-induced micronuclei. In vivo radon exposure was 10.6 +/- 1.0 times as effective as acute whole-body 60Co exposure in producing micronuclei in lung fibroblasts. Different cell lines and exposure conditions resulted in similar effectiveness factors. Such ratios help evaluate the biological damage, hazard and risk associated with radon inhalation.

Adult leukemia risk and personal appliance use: a preliminary study.

The hypothesis that use of personal electric appliances may be associated with increased risk of acute nonlymphocytic leukemia in adults was tested using interview data from a previously completed case-control study of 114 cases and 133 controls conducted between 1981 and 1984. Cases were obtained from a population-based cancer registry in western Washington state, and controls were obtained from the same area by random digit dialing. Of 32 electrical home appliances for which data on use were available for adult acute nonlymphocytic leukemia cases and controls, three motor-driven personal appliances (electric razors, hair dryers, and massage units) were selected a priori because their use represents exposure to higher peak magnetic fields than that from most other home appliances. When compared on an "ever used" versus "never used" basis, use of one or more of these appliances was not associated with increased risk of leukemia in the population studied (odds ratio (OR) = 0.71, 95% confidence interval (CI) 0.41-1.24). When the appliances were considered individually, massage units were more likely to have been used by cases than by controls (OR = 3.00, 95% CI 1.43-6.32), while hair dryers were more likely to have been used by controls than cases (OR = 0.38, 95% CI 0.22-0.66). There was a nonsignificant tendency for electric razor use to differentiate the cases from controls (OR = 1.33, 95% CI 0.80-2.23). When reported daily time of use was stratified, there was no overall increased risk with increased time of use except for electric razors (p < 0.05). In addition to the analysis of appliance use data from the case-control study, the authors obtained several models of these motor-driven personal appliances and characterized the magnetic fields they produce. Magnetic field flux density, or the B-field, and spectral measurements showed that partial body exposure from such appliances may exceed 0.5 mTesla (root mean squared) at rates-of-change exceeding 10 Tesla/sec. These epidemiologic data must be interpreted cautiously because the number of cases is limited and because of proxy reporting of appliance use for deceased cases. Nevertheless, the authors believe these data indicate that peak magnetic field exposure from personal appliances warrants further investigation as a possible risk factor for acute nonlymphocytic leukemia in adults.

Serum and urine biochemical diversity among wild-caught and colony-born Aotus nancymae.

Serum and urine analytes were compared between adult wild-caught and adult colony-born owl monkeys (Aotus nancymae), to determine if normative clinical pathology data were similar. Significant differences (P < or = 0.05) were noted in serum protein, glucose, sodium, urine calcium, calcium clearance, and fractional clearance of calcium between the two groups. The results suggest that reference data for feral owl monkeys is not completely applicable to colony-born animals, however, the differences are too small to be of clinical significance.

Experience with a routine fecal sampling program for plutonium workers.

A quarterly fecal sampling program was conducted at the U. S. Department of Energy's Hanford site for congruent to 100 workers at risk for an intake of plutonium oxide and other forms of plutonium. To our surprise, we discovered that essentially all of the workers were excreting detectable activities of plutonium. Further investigation showed that the source was frequent, intermittent intakes at levels below detectability by normal workplace monitoring, indicating the extraordinary sensitivity of fecal sampling. However, the experience of this study also indicated that the increased sensitivity of routine fecal sampling relative to more common bioassay methods is offset by many problems. These include poor worker cooperation; difficulty in distinguishing low-level chronic intakes from a more significant, acute intake; difficulty in eliminating interference from ingested plutonium; and difficulty in interpreting what a single void means in terms of 24-h excretion. Recommendations for a routine fecal program include providing good communication to workers and management about reasons and logistics of fecal sampling prior to starting, using annual (instead of quarterly) fecal sampling for class Y plutonium, collecting samples after workers have been away from plutonium exposure for a least 3 d, and giving serious consideration to improving urinalysis sensitivity rather than going to routine fecal sampling.

Urinary enzyme concentrations in the owl monkey (Aotus nancymae).

The activity of three urinary enzymes, alkaline phosphatase (ALP), aspartate aminotransferase (AST), and N-acetyl-beta-D-glucosaminidase (NAG), was evaluated in 71 adult owl monkeys. Fifty-six animals had normal renal function, while 15 had evidence of renal dysfunction. Urinary enzyme: urinary creatinine ratios (UE: UCr) were also determined. The activity for NAG was similar to that of other species, while ALP and AST were higher. Regression analyses revealed that urinary enzymes and UE:UCr were significantly correlated (P < or = 0.0001) with indices of renal damage and could identify active renal disease.

Comparison of blood and urine analytes between two karyotypes of owl monkey, Aotus nancymae and Aotus vociferans.

Serum and urine analytes were compared between two karyotypes of owl monkey, Aotus nancymae and A. vociferans, to determine if normative clinical pathology data obtained from one karyotype were applicable to the other. Statistically significant differences (P < or = 0.05) were noted in serum calcium, serum phosphorus, serum sodium, serum potassium, serum urea nitrogen, urine calcium, calcium clearance, and fractional clearance of calcium between the two karyotypes. The results suggest that A. vociferans regulate calcium-phosphorus and electrolyte homeostasis in a manner different from that of A. nancymae.