Evaluation of background radiation level and excess lifetime cancer risk in Doon valley, Garhwal Himalaya

Radionuclides such as Ra-226, Th-232 & K-40 occurs naturally in the earth crust from its creation and are main contributor to the dose received by human beings. The present study was carried-out in the Doon valley which is outlined in the Main Boundary Thrust (MBT) region of Garhwal Himalaya in Uttarakhand, India. The collected soil/rock samples were analyzed by NaI(Tl) Gamma ray spectrometry for the analysis of radionuclides and hence measuring the various health hazard indices and Excess lifetime cancer risk. Radionuclide (226Ra, 232Th & 40K) content were found to vary from 47 ± 9 to 442 ± 50 Bq Kg−1, 45 ± 17 to 101 ± 16 Bq Kg−1 & 320 ± 281 to 947 ± 197 Bq Kg−1 respectively and were higher than the world average values which are 35 Bq Kg−1, 30 Bq Kg−1 and 400 Bq Kg−1 respectively. Higher radionuclide content contributes to higher amount of absorbed doses which was found to vary from 93 to 259.6 ηGyh−1 with a mean value of 112.5 ηGyh−1 and Gamma index which found to vary from 0.73 to 1.92 with a mean value of 0.96. Lastly, on the basis of annual effective doses received to humanoid, Excess lifetime cancer risk was measured which varies from 0.48 × 10–3 to 1.34 × 10–3 with an average value of 0.65 × 10–3 and was much below the world’s average value of 1.45 × 10–3.

Assessment of Background Radiation, Annual Effective Dose and Excess Lifetime Cancer Risk in Gonabad City

Purpose: Humans are always exposed to ionizing radiation from their environment, which can have destructive effects. This study aimed to measure background gamma radiation and estimate annual effective dose and excess cancer risk in Gonabad city. Materials and Methods: The dose rate due to indoor and outdoor background radiation was measured by RDS-30 radiation survey meter at five zones on the map, including North, South, East, West, and center. Then, the annual effective dose and excess lifetime cancer risk were calculated by associated equations. Results: Mean dose rates for outdoor and indoor spaces were 0.111 µSv/h and 0.139 µSv/h, respectively. The mean background dose rate of indoor space was significantly higher than that of outdoor space. Annual effective dose and excess lifetime cancer risk were obtained as 0.817 and 2.85×10-3, respectively. Conclusion: Background radiation dose, annual effective dose, and cancer risk for Gonabad city were higher than global ones. Further investigations are needed to encompass internal background radiation doses in annual effective dose.

Assessment of Natural Radioactivity in Some Soil Samples from Kutha District in Babylon Governorate, Iraq

The activity concentrations of natural radionuclides of the elements (40K, 238U and 232Th), collected from Kutha district of Babylon governorate are studied and evaluated. Twenty soil samples with (0-15) cm in depth are collected. Gamma spectrometer NaI (TI) source is used for calibration. The radioactivities of natural isotopes K-40, U-238 and Th-232, were assessed. These studies show that radio activities of isotopes are acceptable according to the standard levels. Also, the activity of radium equivalent, the rate of annual effective dose, average air volume and external risk index are evaluated. The results are found within the internationally tolerable values. The results show that the mean of the radioactivity of 238U is (19.1565)Bq / kg, while it is (54.501) Bq/kg for 232Th and (179.578) Bq/kg for 40K. The study results showed that the average of radiological effects, like the Radium equivalent (Raeq), the rate of absorbed dose (Dr), the index of external hazard (Hex), the index of internal hazard (Hin), the index of representative gamma hazard (Iγ), the Annual Effective Dose Equivalent (AEDE) and the Excess Lifetime Cancer Risk (ELCR) are as follow: 110.920 Bq/kg, 50.1838 nGy/h, 0.29953, 59.1530, 27.996, 0.34 mSv/y and 1.268x10-3, respectively. Keywords: Natural radioactivity, Absorption, External hazard, Effective annual dose, Excess lifetime cancer risk.

ASSESSMENT OF RADIATION EXPOSURE LEVEL IN BLACKSMITHING WORKSHOP IN GOMBE, GOMBE STATE

Measurement of terrestrial background ionizing radiation of blacksmith workshops of Gombe State, Nigeria was carried out using well-calibrated Geiger-Muller counter meters and a meter tape. The measured average exposure rate of two line-sections are 0.018±0.002 and 0.017±0.002 mRh-1. Estimated equivalent dose rates for the two line-sections are 1.50 and 1.45 mSvy-1. The average absorbed dose rates estimated in line-section one and line-section two are 154.94 and 149.97 nGyh-1 respectively. Annual effective dose equivalent (AEDE) of 0.48 mSvy-1 was obtained for outdoor exposure in line-section one while in line-section two, AEDE was 0.23 mSvy-1. The calculated mean excess lifetime cancer risk values for the blacksmith workshop sections are 0.83x 10-3 and 0.80 x 10-3. The obtained values for background ionizing radiation in the line-sections of blacksmith workshop were above the recommended standard limit by ICRP while the absorbed doses (D) were above the recommended value and AEDE calculated in two line-sections of blacksmithing workshops were within the safe values this implies that blacksmithing activities in these areas may not influence the doses received by public. The excess lifetime cancer risk (ELCR) estimated were higher than their world permissible values of 0.29 x 10-3 respectively. The calculated dose to organs showed that the testes have the highest organ dose of 0.153 mSvy-1while liver has the lowest organ dose of 0.086 mSvy-1. This result shows that exposure to

Development of Nationwide Excess Lifetime Cancer Risk Evaluation Methods with Comprehensive Past Asbestos Exposure Reconstruction

Although exposure to asbestos via various routes has been acknowledged, comprehensive exposure and risk assessment methods have not been developed at the national level. We conducted a study to reconstruct comprehensive past asbestos exposure estimations and to suggest a method to calculate the Excess Lifetime Cancer Risk (ELCR) of Koreans. The past occupational exposure reconstruction was conducted by rebuilding the previous general population job-exposure matrix (JEM). The para-occupational and household exposure estimation was based on the pooled analysis of data from other countries as well as Korea. The neighborhood exposure from occupational sources by distance was estimated by the exponential decay model. As a result, 141 JEM exposure groups across four periods including ~79, the 80s, 90s, 2000s with a ratio of 2.0:1.0:0.5:0.05 were reconstructed. The para-occupational and household exposures were 11% and 1% of the JEM respectively. The environmental exposure source concentration from outside occupational exposure was 2.5% of the inside concentration. The ratio of the concentration of environmental exposure source (C0) to distance d (Cd) was exp−kd with a decay constant k of 6.834. The mean concentrations (f/cc) were 2.28 × 10−3 for outdoor, 4.65 × 10−5 for indoor, 1.95 × 10−2 for transportation activity, 4.44 × 10−2 for agricultural activity, and 4.68 × 10−2 for daily life activity in naturally occurring asbestos areas. Indoor and outdoor asbestos concentrations from living in a slate roof house were 1.73 × 10−6 and 2.70 × 10−8, respectively. For improved generalizability, validity, and applicability of the proposed method, further studies on each route with real assessments and experiments are required.

Low-level ionizing radiation and associated risk in an urban environment: the importance of both paving and building materials

<p>Natural radioactivity depends on primordial radionuclides which decay across a chain of transformations to achieve a stable nuclear state. Transformations involve the emission of particles and photons whose energy can be harmful to organisms even at low-dose. K-40, Th-232 and U-238 are responsible for most of the natural emission of gamma rays from the earth’s crust and volcanic rocks are, in general, the most emissive materials.</p><p>Volcanic rocks and related volcano-sedimentary lithified deposits have been quarried for construction purposes and for road paving, since the Greek times, in the area where the city Naples is located, halfway between the volcanic districts of Phlegrean Field and Mt. Somma-Vesuvius, respectively. For centuries, lithified pyroclastic products, such as grey or yellow tuffs, have been used mainly for buildings and vertical structures; lava blocks from Phlegrean Fields and, since 18<sup>th</sup> century, from Vesuvian effusive materials have been historically used to pave the roads of the old town.</p><p>However, in the last few decades, <span>deteriorated </span><span>historical paving materials of some roads serving areas undergoing renovation have been partially replaced by volcanic materials of Etnean origin (proceeding from Sicily, indeed) or covered/replaced by non-geologic materials (NGMs) (e.g., asphalt).</span></p><p>Considering that 120,000 people live in the old town (over an area of 4 sqkm) being potentially exposed to low-dose ionizing gamma radiations, a survey to estimate the contribution of geological materials to the ambient dose equivalent rate (ADER) was completed. A radiological risk assessment was also completed.</p><p>Specifically, 2548 measurements of ADER (µSv/h) were made in the open air at 0.2 (ADER0.2) and at 1 m (ADER1) above the ground, respectively, using a handheld gamma-ray spectrometer. Besides, a total of 13 samples of paving materials were collected and analyzed by means of a high purity germanium detector at the Center for Ecological-Noosphere in Armenia.</p><p>Results revealed a significant activity of all materials, except for NGMs. ADER1 and ADER0.2 values ​​showed a strong dependence on the distance from the ground in the streets paved with geologic materials, while the distance from the ground resulted to be not relevant for ADER in areas paved by NGMs .</p><p>Based on the ADER1 data, a Monte Carlo simulation was conducted to calculate the outdoor excess lifetime cancer risk (ELCRout) for the population of the study area and for each district belonging to the old town.</p><p>In one of the districts showing the highest average ELCRout, 51 additional ADER1 measurements were also conducted inside private dwellings to assess the indoor ELCR (ELCRin). Finally, the total excess lifetime cancer risk (ELCRtot) was estimated by summing values of ELCRout to ELCRin.</p><p>The average ELCRout obtained for the entire study area (1.33E-03) and for individual districts (from 5.20E-04 to 1.44E-03) exceeds the world average reference value (2.9E-04).</p><p>ELCRin (4.35E-03) and ELCRtot (5.79E-03) are also higher than the average reference values proposed in the literature.</p><p>This study revealed that low-dose gamma radiations, emitted by paving or building materials of volcanic origin can pose a radiological risk to human health.</p>