Radon measurements by nuclear track detectors in dwellings in Oke-Ogun area, South-Western, Nigeria

Comprehensive assessment of radiological hazards in chromite mines at Khanozai and Muslim Bagh, Balochistan, Pakistan

The concentrations of natural radioactivity in soil samples collected from chromite mines of two different towns, Khanozai and Muslim Bagh, districts of Pishin and Killa Saifullah, respectively, were measured using a high purity germanium (HPGe) detector. The average values of 226Ra, 232Th and 40K in soil of Khanozai chromite mines were found to be 26.414, 37.321 and 404.561 Bq kg-1, respectively. In Muslim Bagh chromite mines, these values were found to be 17.59, 29.677 and 380.475 Bq kg-1, respectively. The maximum average values of radium equivalent (Raeq), external hazard index (Hex) and internal hazard index (Hin) were found to be 110.851, 0.299 and 0.356 Bq kg-1, respectively, in chromite mines of Khanozai, while the minimum average values were found to be 89.253, 0.276 and 0.275 Bq kg-1, respectively, in Muslim Bagh chromite mines. Similarly, maximum average values of absorbed dose rate (DR), external absorbed dose rate (Dout) and internal absorbed dose rate (Din) were found to be 50.742, 54.651 and 77.058 nGy h-1, respectively, in soil of Khanozai chromite mines while the minimum average values were found to be 41.311, 44.385 and 62.583 nGy h-1, respectively, in Muslim Bagh chromite mines. Also, the maximum average values of annual effective dose risk (AEDR), gamma activity index (Iγ) and alpha activity index (Iα) were found to be 2.30 × 10-1 mSv y-1, 0.409 and 0.132, respectively, in soil of Khanozai chromite mines while the minimum average values were found to be 2.02 × 10-1 mSv y-1, 0.333 and 0.087, respectively, in Muslim Bagh chromite mines. The values were found to be below the world permissible range. Therefore, it is concluded that the chromite mines under the study have no health hazards.

Seasonal Indoor Radon Assessment and Estimation of Cancer Risk: A Case Study of Obafemi Awolowo University Nigeria

Human exposure to indoor radon has been a subject of continuous concern due to its health implications, especially as it relates to lung cancer. Radon contaminates indoor air quality and poses a significant health threat if not abated/controlled. A seasonal indoor radon assessment of residential buildings of Obafemi Awolowo University was carried out to determine radon seasonal variability and to evaluate the cancer risk to the residents. AT-100 diffusion-based track detectors were deployed within living rooms and bedrooms for the radon measurement. During the rainy season, the average indoor radon concentration was 18.4 ± 10.1 Bq/m3, with higher concentrations observed in bedrooms compared to living rooms, whereas the average radon concentration was 19.0 ± 4.4 Bq/m3 in the dry season, with similar radon levels in living rooms and bedrooms. The potential alpha energy concentration values ranged from 1.62 to 7.57 mWL. The annual effective dose equivalent values were below the world average and recommended limits for public exposure. Of the three geological units underlying the residences, the buildings overlying the granite gneiss lithology have the highest radon concentrations with average value of 21.4 Bq/m3. The soil gas radon concentration to indoor radon concentration ratio over the granite gneiss lithology is 0.006. The estimated average lifetime cancer risk due to radon inhalation in the residences indicated a potential risk of cancer development in 178 persons in 100 000 population over a lifetime period. The average indoor radon concentrations were below the recommended limit, requiring no immediate remediation measures. Improved ventilation of residential apartments is recommended to minimize residents' risk to indoor radon.

Comparative study of radon sources and associated health risk in four underground uranium mines

This paper presents a comparative study of the quantitative estimation of ²²²Rn and its health risk from various sources in four underground uranium mines. ²²²Rn exhalation rates from uranium-bearing rocks and backfill materials were estimated by calculating the ²²²Rn concentration accumulated in an enclosed chamber into which radon was exhaled. This comparative study indicates a more significant effect of porosity on the exhalation rates. Dissolved ²²²Rn in mine water was estimated using scintillation cell and bubbler kit. The discrepancy in ²²²Rn concentration in the mines might be attributed to the variation in geological features, ore grade, and porosity. This study revealed that the maximum radon exposure was produced from the backfill mill tailings, followed by uranium ore and mine water in the mines. The radon dose values in the individual mines remained under the safe dose limit of 20 mSv year^-1. The excess lifetime cancer risk (ELCR) and ²²²Rn-induced lung cancer cases (RnLCC) per million persons per year were also estimated.

Relationship between heavy metals and alpha emission rates in breast milk and blood of women

BACKGROUND

The current study determines the relationship between heavy metals and alpha particles emission rates in milk and blood of lactating women in Diwanyah, Iraq.

METHODS

Heavy metals and alpha particle emission rates have been measured using an Atomic Absorption Spectrophotometer and a Nuclear Track Detector.

RESULTS

The results show that Pb, Cd, and Cu in milk are 0.2239 ± 0.0007 ppm, 0.0156 ± 0.0001 ppm, and 0.1811 ± 0.0006 ppm, respectively. Pb, Cd, and Cu in the blood were 0.0898 ± 0.0008 ppm, 0.0432 ± 0.0010 ppm, and 0.1729 ± 0.0004 ppm, respectively. The highest alpha particle emission rate was found to be in age interval from 23 y to 28 y in milk, while the highest alpha particle emission rate was found to be in the age interval from 35 y to 40 y.

CONCLUSIONS

This study concludes that no statistical significance between Pb, Cd, Cu and Eα in milk and blood at level 0.01. The following order of bioavailability was found with heavy metals Cu < Pb < Cd.

Radiometric evaluation of indoor radon levels with influence of building characteristics in residential homes from southwestern Nigeria

Indoor radon (²²²Rn) measurements were carried out using solid state nuclear track detectors (SSNTD) in some dwellings from southwestern Nigeria. This was aimed at statistically assessing influence of building characteristics on the measured radon and estimating excess lifetime cancer risks (ELCR). The measured radon concentrations followed lognormal distribution and were significantly influenced by some building properties. The arithmetic mean (1.60 mSv) of annual effective doses (AEDs) due to indoor radon was observed to be higher than the world average level (1.15 mSv) but less than lower limit (3 mSv) of International Commission on Radiological Protection (ICRP). The evaluated excess lifetime cancer risk ranged from 1.5 to 28.1 (MPy)^-1 with an average value of 6.3 (MPy)^-1, indicating that after exposure to indoor radon for 70 years, 6 people in every 1000 are likely to suffer the risk of developing lung cancer. Adequate ventilation systems were recommended for houses with high level of radon to avoid unnecessary exposure to radon. However, the investigated data would form important component of the database required to set up guidelines and policy of controlling radon at home.

Indoor radon concentration measurements in some dwellings of the Penisola Sorrentina, South Italy

In this study, the indoor radon concentrations have been measured in 93 dwellings of the Penisola Sorrentina, using LR115 detectors. The detectors were placed in the bedrooms and living rooms for two consecutive semesters starting from December 2010 to December 2011. The annual average indoor radon concentrations vary from 25 to 722 Bq m(-3), with a mean value of 132 ± 114 Bq m(-3). Correlation between indoor radon measurements and same building characteristics was also studied. Based on the obtained results, the mean annual effective dose of 2.4 mSv y(-1) received by inhabitants was estimated.

Radon measurements by nuclear track detectors in secondary schools in Oke-Ogun region, Nigeria

Radon measurements were performed in secondary schools in the Oke-Ogun area, South-west, Nigeria, by solid state nuclear track detectors (SSNTDs). About seventy CR-39 detectors were distributed in 35 high schools of the Oke-Ogun area. The CR-39 detectors were exposed in the schools for 3 months and then etched in NaOH 6 N solution at 90 °C for 3 h. The tracks were counted manually at the microscope and the radon concentration was determined at the Radioactivity Laboratory, Department of Physics, University of Trieste, Trieste, Italy. The overall average radon concentration in the surveyed area was 45 ± 27 Bq m(-3). The results indicate no radiological health hazard. The research also focused on parameters affecting radon concentrations such as the age of the building in relation to building materials and floor number of the classrooms. The results show that radon concentrations in ground floors are higher than in upper floors.