Assessment of annual effective dose from radium isotopes in groundwater samples in households along the lower Mekong River

Determination of the internal dose due to the intake of 226Ra and 210Pb in drinking water from deep wells in the Metropolitan Region of Recife-Brazil

The Metropolitan Region of Recife, the capital of the state of Pernambuco in northeastern Brazil, has a high demographic density and developed under a region of marine phosphorus with high concentrations of phosphate that naturally contains uranium ore, producing ionizing radiation from descendants of the radioisotope ²³⁸U where ²²⁶Ra and ²¹⁰Pb are of great importance in verifying the probable harmful effects on human health due to environmental radioactivity. The supply of drinking water is the responsibility of the state-owned company COMPESA which uses wells of great depth to complete the supply of drinking water for the entire population. COMPESA and the RAE Group of the Federal University of Pernambuco developed a joint project to assess the concentrations of ²²⁶Ra and ²¹⁰Pb and estimate the equivalent and effective doses caused by ingesting these radiation sources. According to the above, this research aimed to evaluate concentrations of ²²⁶Ra and ²¹⁰Pb in drinking water samples from 110 deep wells in Recife. The activities of ²²⁶Ra and ²¹⁰Pb ranged from 1.4 ± 0.3 to 119.3 ± 12.9 and from 25.6 ± 3.3 to 563.2 ± 45.6 mBq.L^-1, with arithmetic means of 48.1 ± 3.8 and 231.1 ± 20 mBq.L^-1, respectively. The equivalent doses average in bone tissue due to ²²⁶Ra and ²¹⁰Pb were 0.45 ± 0.04 and 3.9 ± 0.37 mSv.y^-1, and the annual average effective doses were 0.01 ± 0.00 and 0.13 ± 0.01 mSv.y^-1, respectively.

Radiation exposure in a region with natural high background radiation originated from rare earth element deposits at Bat Xat district, Vietnam

Surface deposits of rare earth element (REE) were identified in the Bat Xat district, Northern Vietnam. As the area is inhabited, an in-depth investigation was carried out to assess the radioactivity levels and to evaluate the radiation exposure and radiological risks for the population. Samples of REE ore, soils, water and several foods locally produced were collected and analyzed by gamma spectrometry for determination of ²³²Th, ²²⁶Ra, and ⁴⁰ K. Radon (²²²Rn and ²²⁰Rn) measurements were carried out in dwellings at the villages located near by the REE deposit area, and in Hanoi for comparison. Based on the measured radionuclide concentrations, several radiological parameters were calculated to evaluate the radiological risks for the population and to compare with worldwide values. Results indicate that the representative person of the most exposed group living near the REE deposits may receive a total annual effective dose as high as 37.9 ± 10.6 mSv, i.e., approximately 16 times the world average dose of 2.4 mSv y^-1. Consequently, this area should be considered a high background radiation area. Exposure to external radiation and internal radiation from ingestion and inhalation of radionuclides were assessed separately. Radon inhalation contributed to approximately 70% of the total annual effective dose, with both radon isotopes contributing significantly, while the ingestion of local foods and water gave minor contributions to the total effective dose. Several measures were considered to improve the radiation safety and recommendations are given to relocate the most exposed members of the population.

The assessment of the annual effective dose due to ingestion of radionuclides from drinking water consumption: calculation methods

In the present paper the different ways of assessing the annual effective dose due to ingestion of radionuclides by drinking water consumption were examined and exemplified. On a set of 10 samples the gross alpha activity, the gross beta activity, the concentration of 210Po, 210Pb, 238U, 232Th and, 226Ra were measured. The highest annual effective dose values assessed by relying on the investigated sample set were found by using the rationale according to which all the gross alpha and beta activity is due to the alpha and beta radionuclide, with the highest effective dose coefficient, namely 210Po and 210Pb/228Ra, respectively.

Assessment of radioactivity and chemical contaminants in domestic water at supply stations in Long Phu District, Vietnam, to prevent public health risks

This paper presents information on the concentration of radioactivity and chemicals at 12 water stations that used groundwater as their raw water supply source. The groundwater's radioactivity was higher than the treated, tap, and surface water, but lower than the national and international recommendations. At five stations (41.7%), the gross alpha contents were higher than the levels advised by Vietnam's regulations, but met the WHO and IAEA's recommendations. The mean activity (Bq L^-1) gross alpha, gross beta, Ra-224, Ra-226, and Ra-228 were 0.093 ± 0.012, 0.221 ± 0.020, 0.031 ± 0.004, 0.028 ± 0.004, and 0.035 ± 0.001, respectively. The contribution of Ra-226 to the gross alpha was in a range of 23%-60% (r = 0.91, p value <0.001), and the ratio of Ra-226/Ra-228 ranged from 0.49-1.06. For the treated and tap water, each age groups' annual committed effective dose was lower than the international regulations. The concentration of the total dissolved solids, sulfate, chloride, sodium, barium, and manganese met the national regulations. However, during the rainy season, the surface water in the area was affected by saltwater intrusion, with salinity up to 4.1‰. Discriminant analysis was applied to study the differences among the water groups. As a result, the treated and tap water were separated from the others.