Radioactive Contaminants in U.S. Drinking Water and Water Quality Disparities

Radioactive contaminants, such as radium, radon, and uranium isotopes are naturally present in drinking water, and gas and oil extraction like hydraulic fracturing can exasperate radionuclide leakage into groundwater. The concentration of radionuclide in drinking water is dependent upon the water source and the underlying lithology within the aquifers. In United States, the Environmental Protection Agency regulates the level of radioactivity in drinking water via the gross alpha test, which is conducted to measure the emitted alpha particles as a result of the radioactive elements’ natural decay. Radionuclides, such as radium and uranium, are known to cause bone cancer and other forms of cancer. Communities with crippling water purification infrastructure may be at a higher risk of being exposed to radionuclides, and this is a significant environmental justice concern. The radionuclide concentrations for the metropolitan or most populated city in each state in the United States and its territories (Puerto Rico, US Virgin Islands and Guam) were analyzed and correlated to the annual household income, to determine any disparities that maybe present. Lower income communities had elevated levels of radionuclides when compared to higher income communities which had lower frequency in elevated radionuclide contaminants.

Determination of Radioactive Contaminant 137Cs (Fission Product) and Comparison with Natural 40K Present in Mexican Strawberries

Several previous papers have been published about radioactive contamination in Mexican soil, marine sediments and foodstuffs. Ever since, results have been according to expectation, mainly consisting of natural isotopes in small concentration. Continuous research leads with the surprising finding of fission product 137Cs (t1/2 = 30 years) in strawberries produced in different states, about 2000 km away from each other. Never before, such contaminant has been observed in foodstuffs, produced in this country. The aim of this work is to report the presence of 137Cs in Mexican strawberries and compare the activity of such contaminant with the natural radioactivity of 40K (t1/2 = 1.28 × 109 years), through gamma spectrometry. Eventually, the specific activity of 137Cs observed in samples FM4, FM5 and FBC is respectively 0.7, 0.8 and 0.3 Bq/kg. The limits established in CODEX-STAN-193-1995 for 137Cs are 1000 Bq/kg, so all samples meet the recommendation. It’s presence now in vegetables result with enough interest to be known and considered in the near future to measure the possible effect that radioactive contamination could reach after nearly 80 years from second world war, where no nuclear test has been performed, nuclear accident occurred, neither nuclear weapon has ever been used.

Natural and Artificial Radionuclides in River Bottom Sediments and Suspended Matter in the Czech Republic in the Period 2000-2010

The concentrations of natural radionuclides, radium-226, radium-228, and potassium-40, and the artificial radionuclide caesium-137, in river bottom sediments and suspended matter were monitored in the Czech Republic by the Czech Hydrometeorological Institute during the period 2000-2010 and 2001-2010 respectively. The data were used to evaluate the natural background levels of these radionuclides and the impact of human activities on the water environment. For potassium-40 in sediments, the natural background level was estimated to be 570 Bq/kg. To evaluate the background level for radium-226, the river sites affected by human activities (mining and processing uranium ore, coal) were eliminated from the assessment. The average natural background values were 47.8 Bq/kg for radium-226 and 47.2 Bq/kg for radium-228 in sediments and 86.5 Bq/kg for radium-226 and 87.9 Bq/kg for radium-228 in suspended matter. The river sediments were identified as good indicators of radioactive contamination, especially radium-226, which recorded historic contamination due to former uranium mining and milling. The radium-226 contamination rate was assessed using the ratio of radium-226 to radium-228. This ratio was used to classify sediment according to the relative contamination from the uranium industry. The residual contamination of caesium-137 due to the Chernobyl accident in 1986 was also assessed. Average values of caesium-137 were 14.0 Bq/kg in sediments and 25.0 Bq/kg in suspended matter.

Study of CdMoO4 crystal for a neutrinoless double beta decay experiment with ^116Cd and ^100Mo nuclides

The scintillation properties of a CdMoO4 crystal have been investigated experimentally.The fluorescence yields and decay times measured from 22 K to 300 K demonstrate that CdMoO4 crystal is a good candidate for an absorber for a bolometer readout,for both heat and scintillation signals.The results from Monte Carlo studies,taking the backgrounds from 2ν2β of^100 42Mo ^116 48Cd） and internal trace nuclides ^214Bi and ^208Tl into account,show that the expected sensitivity of a CdMoO4 bolometer for neutrinoless double beta decay experiments with an exposure of 100kg·years is one order of magnitude higher than those of the current sets of the limT1/2^0νββ of ^100 42Mo and ^116 48Cd.

Determination of thorium in the hair and urine of workers and the public in a rare earth mining area

Objective:To assess the thorium exposure of the mine workers and the public to a typical rare earth mine and estimate the resultant committed effective dose to them.Methods:A total of 79 volunteers were selected in this survey,including 69 mine workers and 10 local residents living about 4 km away from the mine site.Urinary samples were collected from 79 volunteers,with 65 hair samples from 57 workers and 8 local residents.The thorium concentrations in urinary and hair samples were determined by using inductively coupled plasma mass spectrometry.The committed effective doses were estimated based on the urinary samples collected and the parameters as recommended by ICRP Publication 137.Results:Thorium concentrations in the samples from the workers ranged from 19.0 to 2388.8 ng/g in hair with median of 149.8 ng/g,and in urine 18.3–906.1 ng/L with median of 59.6 ng/L,respectively.The median values of thorium concentrations were 11.8 ng/g in hair and 32.40 ng/L in urine for the public respectively.The thorium concentrations in urinary and hair samples of the workers were not only higher than those of the residents in the local area,but also than those of non-occupationally exposed populations as reported.The median values of committed effective dose were estimated to be 1.51 mSv for the workers and 781μSv for the local residents,respectively.Conclusions:The residents in the local area,and especially the workers,have been subject to long term thorium exposure.More attention should be paid to the radiological hazards of thorium to the workers and local residents.