Distribution of 137Cs in soil along Ta-han River Valley in Tau-Yuan County in Taiwan.

Environmental 137Cs contamination was suspected from accidents at spent fuel storage pits of a research reactor site in the Ta-han River valley in Taiwan. In order to further characterize this contamination, soil samples were collected and measured by a gamma-spectroscopy system in 1999. It was found that 137Cs contamination is distributed up to 4 km from the reactor in an area covered mostly by rice and plant fields. 137Cs concentration in the topsoil ranged up to about 1000 Bq kg-1, as compared with soil beyond the contaminated area, which does not exceed 15 Bq kg-1. Spatial distribution of 137Cs was characterized by strong non-uniformity, which complicated our understanding of the distribution pathway of the radionuclides. The highest concentrations of 137Cs, up to more than 1000 Bq kg-1, were found within a few rice fields. The relative location of these rice fields and the water supplies from local streams suggested that the 137Cs was distributed along water pathways in the valley.

An evaluation of 222Rn concentrations in Idaho groundwater.

Factors potentially correlated with 222Rn concentrations in groundwater were evaluated using a database compiled by the U.S. Geological Survey. These included chemical and radiological factors, and both well depth and discharge rate. The 222Rn concentrations contained within this database were examined as a function of latitude and longitude. It was observed that the U.S. Geological Survey sample locations for 222Rn were not uniformly distributed throughout the state. Hence, additional samples were collected in southeastern Idaho, a region where few 222Rn in water analyses had been performed. 222Rn concentrations in groundwater, in Idaho, were found using ANOVA (alpha = 0.05) to be independent of the chemical, radiological, and well parameters thus far examined. This lack of correlation with other water quality and well parameters is consistent with findings in other geographical locations. It was observed that an inverse relationship between radon concentration and water hardness may exist.

Sampling and analysis for radon-222 dissolved in ground water and surface water.

Radon-222 is a naturally occurring radioactive gas in the uranium-238 decay series that has traditionally been called, simply, radon. The lung cancer risks associated with the inhalation of radon decay products have been well documented by epidemiological studies on populations of uranium miners.The realization that radon is a public health hazard has raised the need for sampling and analytical guidelines for field personnel. Several sampling and analytical methods are being used to document radon concentrations in ground water and surface water worldwide but no convenient, single set of guidelines is available. Three different sampling and analytical methods-bubbler, liquid scintillation, and field screening-are discussed in this paper. The bubbler and liquid scintillation methods have high accuracy and precision, and small analytical method detection limits of 0.2 and 10 pCi/l (picocuries per liter), respectively. The field screening method generally is used as a qualitative reconnaissance tool.

Effect of vitamin A on lung tumorigenesis in irradiated and unirradiated strain A mice.

The effect of vitamin A (retinyl acetate) on lung tumor development in strain A mice exposed to radiation was assessed. Four groups of 75 mice were utilized. Two groups were fed a low vitamin A diet (less than 100 IU/100 g diet) and the other 2 were fed a high vitamin A diet (800 IU/100 g diet). After 2 weeks one group maintained on the high vitamin A diet and one group maintained on the low vitamin A diet were given an acute dose of 500 rad of gamma radiation to the thoracic region. Circulating levels of plasma vitamin A in all 4 groups of mice were monitored. A difference in circulating vitamin A in the mice maintained on high and low vitamin A diet became evident by 20 weeks and continued for the duration of the experiment. Mice were killed 18, 26 and 40 weeks post-irradiation, their lungs were removed and the number of surface adenomas were counted. There was a significant increase in the number of mice bearing lung tumors and the mean number of lung tumors per mouse in the irradiated group maintained on the high vitamin A diet at 40 weeks post-irradiation as compared to the irradiated group maintained on a low vitamin A diet. Under the conditions of this experiment the development of pulmonary adenomas in irradiated strain A mice appears to relate directly to circulating levels of vitamin A.

Background atmospheric 222Rn concentrations outdoors and indoors: a review.

The sources of outdoor and indoor atmospheric radon are examined. The variation of outdoor atmospheric radon with time of day, time of year, altitude and geographic location is quantitatively assessed. Average values of outdoor atmospheric radon concentrations are examined and it is estimated that the mean value for normal areas of the contiguous United States lies in the range of 100-400 pCi/m3 and is probably about 250 pCi/m3. Values for Alaska and Hawaii are an order of magnitude lower. Indoor atmospheric radon concentrations are found to vary with time of day, geographic location and story above ground.

Iodine-131 levels in sludge and treated municipal wastewaters near a large medical complex.

Iodine-131 was found to dominate the gamma spectra of dried sludge and concentration liquid effluent samples from a sewage treatment plant serving the area containing the Texas Medical Center in 1975. The concentration of Iodine-131 varied considerably on a time scale of weeks but was fairly stable in the course of a single day. The partition of Iodine-131 between the dried sludge and the liquid effluent was found to be reasonably constant during the sampling period. Knowledge of the concentration in these phases and the daily output of sludge and effluent let to be estimate of an annual discharge of over one Curie of Iodine-131. Circumstantial evidence linking this discharge to the practice of nuclear medicine in the area is considered strong, but an attempt to correlate variation in the effluent activity with actual nuclide use was inconclusive due, among other reasons, to an insufficient clinical data base. An analysis of possible exposure pathway indicated that negligible human exposure resulted from the Iodine-131 released primarily because the receiving body of water is a saline industrial waterway. A more extensive analysis would be in order for a similar plant discharging treated wastewaters into an inland water system.

Environmentally acquired lead in the laughing gull, Larus atricilla.

Lead concentrations were measured in eggs, prefledgings and adult laughing gulls collected near Galveston, Texas. No lead was found in eggs. Prefledgling and adult birds had lead ranging from zero to 16 mug/g wet tissue. Liver had the greatest lead concentrations followed by brain, heart and skeletal muscle. There were no significant differences in lead concentrations between fledglings and adults or between males and females.