Distribution of radon and risk assessment of its radiation dose in groundwater drinking for village people nearby the W-polymetallic metallogenic district at Dongpo in southern Hunan province, China

Radon and lung cancer: Current status and future prospects

Beyond tobacco smoking, radon takes its place as the second most significant contributor to lung cancer, excluding hereditary and other biologically related factors. Radon and its byproducts play a pivotal role in exposing humans to elevated levels of natural radiation. Approximately 10-20 % of lung cancer cases worldwide can be attributed to radon exposure, leading to between 3 % and 20 % of all lung cancer-related deaths. Nevertheless, a knowledge gap persists regarding the association between radon and lung cancer, impeding radon risk reduction initiatives globally. This review presents a comprehensive overview of the current state of research in epidemiology, cell biology, dosimetry, and risk modeling concerning radon exposure and its relevance to lung cancer. It also delves into methods for measuring radon concentrations, monitoring radon risk zones, and identifying priorities for future research.

Radon level in groundwater in Kwara State, Nigeria, and the potential radiation dose due to intake

Radon in groundwater for domestic purposes contributes to indoor radon and at high concentration levels could be hazardous to inhabitants. Rn-222 concentrations in 101 groundwater samples from some Local Government Areas (LGAs) of Kwara State, Nigeria, were determined by AlphaGUARD portable radon monitor. The mean activity concentrations for the LGAs varied from 4.28 ± 2.29 to 14.59 ± 8.92 Bq.l-1. Radon concentrations were <100 Bq.l-1 guidance level recommended by CEC and WHO. Eighteen percent exceeded the recommended 11.1 Bq.l-1 by the United States Environmental Protection Agency. All the samples exceeded the 0.1 Bq.l-1 Maximum Permitted Level of the Standard Organization of Nigeria for radionuclide contaminant. Mean effective dose from ingestion was estimated for adults, children and infants. Inhalation dose was also estimated. The mean annual effective doses in five LGAs were higher than the 0.1 mSv reference dose level of committed effective dose from the intake of drinking water for 1 y as recommended by the ICRP.

HIGHLIGHTS

Radon measurement and age-independent effective dose attributed to ingestion of bottled water in Iran: sensitivity analysis

A comprehensive study was made to measure the radon concentration in bottled water available in Iran market. The 222Rn concentration in 70 bottled water samples were measured by the sniffing mode technique and RTM 1688-2 (SARAD, Germany) in immediate sampling time and 3 months later for determination of radon decay. The measured radon concentration ranged from 0.003 to 0.618 Bq L-1 in bottled water samples, which were much lower than the recommended value for radon in drinking water by WHO (100 Bq L-1) and United states environmental protection agency (USEPA) (11.1 Bq L-1). The annual effective dose of 222Rn due to ingestion bottled water was also evaluated in this research. The mean annual effective dose due to ingestion of radon in bottled water for adults, children, and infants were estimated to vary from 5.30 × 10-4 mSv-1, 4.90 × 10-4 mSv-1, and 2.15 × 10-4 mSv-1, respectively. Overall, this study indicated that the Iranian people receive no significant radiological risk due to exposure to radon concentration in bottled water brands common consumed in Iranian market.

Investigation of radioactivity level in drinking water resources and soil samples collected from the Hawraman villages, Iraq

In the present study, the RAD7 and NaI(Tl) techniques were utilized to determine the radon concentrations in drinking water resources and the natural primordial radionuclides in soil samples collected from Hawraman villages. The measured radon concentrations ranged from 1.7 ± 0.6 to 34.0 ± 2.8 Bq L^-1 with an arithmetic mean of 14.8 ± 1.2 Bq L^-1. This research demonstrates that roughly 54% of drinking water samples exceed the EPA-recommended level of 11.1 Bq L^-1. For adults, children, and infants, the total annual effective doses for the three types (D_ing, D_inh, and D_di) vary from 7.6 to 149.2 μSv y^-1 with an average of 65.0 μSv y^-1, 8.1-160.0 μSv y^-1 with an average of 69.7 μSv y^-1, and 10.5-207.0 μSv y^-1 with an average of 90.2 μSv y^-1.18.2%, 22.7%, and 36.4%, respectively, of the annual effective dose for adults, children, and infants exceeds the 100 μSv y^-1 level recommended by WHO and UNCEAR 2000. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴ K in soil samples varied from 10.9 ± 0.1 to 32.6 ± 0.2 Bq kg^-1, 18.3 ± 0.4 to 52.1 ± 0.6 Bq kg^-1, and 252.7 ± 2.5 to 585.6 ± 3.7 Bq kg^-1. The arithmetic mean concentrations of ²²⁶Ra, ²³²Th, and ⁴ K were determined to be 19.4 ± 0.2 Bq kg^-1, 36.2 ± 0.5 Bq kg^-1and 426.6 ± 3.2 Bq kg^-1, respectively. This research reveals that the average soil activity concentrations of ²²⁶Ra, ²³²Th, and ⁴ K are within the global average limits of 32, 45, and 420 Bq kg^-1, respectively. Comparing the concentrations to global averages, some soil samples revealed significant amounts of radionuclides, with around 18% of ²³²Th and 41% of ⁴ K. The computed radiological hazard indices of 100% of Ra_eq., 82% of D_out, 82% of E_out, and 95.5% of ELCR_out are all below the internationally recommended levels declared by Unscear 2000.

A systematic review on groundwater radon distribution with human health consequences and probable mitigation strategy

Groundwater radon contamination is a serious global concern for its eco-toxicological effects. The major health hazard occurs due to toxic indoor air inhalation and consumption of contaminated drinking water supplied from different distribution systems, especially groundwater. There are fragmented reports on the measurement of radon contamination and their health consequences with physical radon removal strategies as well as characterization of inhabitant microbial communities. As it concerned with human health, collective information is much essential on their groundwater distribution, their physicochemical properties and possible mitigation strategies, not done so far. In such prospect, this review summarizes the physicochemical properties of radon, their sources, global as well as Indian groundwater radon contamination scenario, health effects and inhabitant microbes along with their survival strategies. It also summarizes the physical radon removal techniques and especially emphasizes the microbes based bioremediation process as well as a combination of both as a future effective radon remediation process.

A critical review on the occurrence and distribution of the uranium- and thorium-decay nuclides and their effect on the quality of groundwater

This critical review presents the key factors that control the occurrence of natural elements from the uranium- and thorium-decay series, also known as naturally occurring radioactive materials (NORM), including uranium, radium, radon, lead, polonium, and their isotopes in groundwater resources. Given their toxicity and radiation, elevated levels of these nuclides in drinking water pose human health risks, and therefore understanding the occurrence, sources, and factors that control the mobilization of these nuclides from aquifer rocks is critical for better groundwater management and human health protection. The concentrations of these nuclides in groundwater are a function of the groundwater residence time relative to the decay rates of the nuclides, as well as the net balance between nuclides mobilization (dissolution, desorption, recoil) and retention (adsorption, precipitation). This paper explores the factors that control this balance, including the relationships between the elemental chemistry (e.g., solubility and speciation), lithological and hydrogeological factors, groundwater geochemistry (e.g., redox state, pH, ionic strength, ion-pairs availability), and their combined effects and interactions. The various chemical properties of each of the nuclides results in different likelihoods for co-occurrence. For example, the primordial ²³⁸U, ²²²Rn, and, in cases of high colloid concentrations also ²¹⁰Po, are all more likely to be found in oxic groundwater. In contrast, in reducing aquifers, Ra nuclides, ²¹⁰Pb, and in absence of high colloid concentrations, ²¹⁰Po, are more mobile and frequently occur in groundwater. In highly permeable sandstone aquifers that lack sufficient adsorption sites, Ra is often enriched, even in low salinity and oxic groundwater. This paper also highlights the isotope distributions, including those of relatively long-lived nuclides (²³⁸U/²³⁵U) with abundances that depend on geochemical conditions (e.g., fractionation induced from redox processes), as well as shorter-lived nuclides (²³⁴U/²³⁸U, ²²⁸Ra/²²⁶Ra, ²²⁴Ra/²²⁸Ra, ²¹⁰Pb/²²²Rn, ²¹⁰Po/²¹⁰Pb) that are strongly influenced by physical (recoil), lithological, and geochemical factors. Special attention is paid in evaluating the ability to use these isotope variations to elucidate the sources of these nuclides in groundwater, mechanisms of their mobilization from the rock matrix (e.g., recoil, ion-exchange), and retention into secondary mineral phases and ion-exchange sites.

Burden of lung cancer attributable to household air pollution in the Chinese female population: trend analysis from 1990 to 2019 and future predictions

This study analyzes the long-term trend of the burden of lung cancer attributable to household air pollution in the Chinese female population, from 1990 to 2019, and make predictions for the next decade. Based the data from the 2019 Global Burden of Diseases (GBD 2019), the joinpoint regression model was used to reflect the temporal trend of the burden of lung cancer attributable to household air pollution, and an autoregressive integrated moving average (ARIMA) model was used to predict the burden of disease over the next decade. From 1990 to 2019, the age-standardized mortality and disability-adjusted life years (DALYs) rates of the Chinese female population were higher than the global rates, and the gap due to residential radon increased over time. The burden of lung cancer attributable to solid fuels has shown a significant downward trend while that due to residential radon has increased slightly overall, but remains lower than the former. The burden of lung cancer increased with age, and the peak age of DALYs rates changed from 70 < 75 years in 1990 to 75 < 80 years in 2019. The model predicted that the burden of lung cancer attributable to solid fuels will gradually decrease over the next decade, whereas the burden of lung cancer due to residential radon will gradually increase and surpass the burden due to solid fuels in 2023. Residential radon will become a more important factor of household air pollution than solid fuels in the next decade for the Chinese female population. Future interventions targeted at household air pollution are needed to reduce the burden of lung cancer.

Evaluation of radiation dose from radon ingestion and inhalation in groundwater of a small tropical river basin, Kerala, India

A comprehensive study was conducted to understand the radon (²²²Rn) distribution and associated radiation doses to the public in a small tropical river basin partly set in the western slope of the Southern Western Ghats of Kerala, India. Radon, though detected in all the 71 monitored wells (0.17-68.3 Bq L^-1), exceeded the maximum contamination level (MCL) of 11.1 Bq L^-1 for drinking water recommended by United States Environmental Protection Agency (USEPA) in eight samples from isolated pockets of highland, midland and lowland of the Karamana River Basin (KRB) and found to be well within 100 Bq L^-1, the parametric value suggested by the World Health Organization (WHO) and the European Union (EU). The age-wise total annual effective doses (AEDs) of groundwater radon activity ranged from 0.5-208.4 μSv a^-1 for infants, 0.4-172.2 for children and 0.5-189.7 μSv a^-1 for adults. The results reveal that effective doses due to groundwater radon pose no potential public health risk in the study region. Since there is no previous background information on radon-induced radiation dose in the KRB, this work is a newfangled attempt from a public health point of view.

OCCURRENCE AND DOSE FROM INTAKE OF RADON IN DRINKING GROUNDWATER IN OGUN STATE, NIGERIA

Radon-222 concentrations in groundwater from 10 local government areas (LGAs) of Ogun State were measured using AlphaGUARD radon detector and AquaKIT. The mean activity concentration of radon ranged from 1.23 ± 0.21 to 12.68 ± 18.11 Bq.l-1 corresponding to geometric means (GMs) of 1.22- 6.39 Bq.l-1. The radon concentrations of all the samples were below the World Health Organization and European Commission guidance level of 100 Bq.l-1, with 17% higher than 11.1 Bq.l-1, recommended by the United States Environmental Protection Agency. Mean annual effective dose due to ingestion ranged from 0.020 ± 0.004 to 0.254 ± 0.353 mSv.y-1 (adults), 0.041 ± 0.007 to 0.509 ± 0.705 mSv.y-1 (children) and 0.024 ± 0.004 to 0.297 ± 0.411 mSv.y-1 (infants). That of inhalation varied from 0.303 ± 0.053 to 3.108 ± 4.440 μSv.y-1. The mean annual effective doses of some of the LGAs were higher than the International Commission for Radiological Protection recommended reference dose level of committed effective dose of 0.1 mSv from 1-year consumption of drinking water.