Health effects of naturally radioactive water ingestion: the need for enhanced studies

Assessment of radioactive contamination in anchovy (Engraulis encrasicolus) along the coast of Turkey, Georgia, and abkhazia in the black sea: A status assessment for human health risks

The Black Sea anchovy, Engraulis encrasicolus, is a significant small pelagic fish, making up over 60 % of the total fish caught in the Black Sea. Assessing its radioactive contamination is crucial due to its commercial importance. This study investigated radioactivity levels in anchovy muscle tissues from 11 points along the Turkish, Georgian, and Abkhazian coasts using the gamma spectrometry system. The mean activity concentrations were 1.71 Bq kg-1 for 226Ra, 1.90 Bq kg-1 for 232Th, 121.08 Bq kg-1 for 40K, and 0.64 Bq kg-1 for 137Cs. In this study, 226Ra, a decay product of 238U, was used as a representative of the uranium series, since it is commonly employed as a proxy in environmental assessments under the assumption of secular equilibrium. Significant differences in radionuclide concentrations between stations were observed (p < 0.05). Radiological parameters, including annual effective dose and carcinogenic risk, showed no health risk from consuming anchovy in the studied region.

Cancer risk due to ingestion of naturally occurring radionuclides through drinking water: A systematic review

Naturally occurring radionuclides can, in rare cases, reach high levels in drinking water of specific areas, leading to meaningful radiation exposures upon ingestion. Increased cancer risk is the only well-established health impact of exposure to low-dose radiation. Multiple ecological studies have shown conflicting results about cancer risk in areas of high levels of radionuclides in water. However, such studies have methodological limitations and are generally not highly informative. Studies with individual-level data are scarce and have not established a clear association either. To further investigate this issue, we conducted a systematic review of the literature on cancer risk associated with radionuclide ingestion through drinking water, aiming to summarize and evaluate the current epidemiological evidence. Published studies have examined the effects of uranium, radium, and radon, while potential risks of polonium, radioactive lead, and thorium remain unknown. Existing research is heterogeneous regarding the cancer types assessed and faces methodological challenges, including limitations in exposure assessment, dosimetric uncertainties, low statistical power, and inadequate control of confounding factors. Due to lack of high-quality evidence, it is not possible to confirm or rule out an increased cancer risk among highly exposed populations. While risk assessment based on extrapolation from high dose studies does not suggest an excess cancer risk beyond background variation, such assessment involves considerable uncertainties. Future studies should focus on populations with high radionuclide exposure to provide sufficient exposure contrast, prioritizing radionuclides with high-dose coefficients and cancers in tissues with the highest radionuclide deposition.

Uranium in Drinking Water and Bladder Cancer: A Case-control Study in Michigan

ABSTRACT

Uranium is naturally occurring in groundwater used for drinking; however, health risks from naturally occurring concentrations are uncertain. Uranium can cause both radiological and chemical toxicity following ingestion. Bladder and kidneys receive a dose when uranium is excreted into the urine. Investigate the association between uranium in drinking water and bladder cancer risk in a case-control study. A population-based bladder cancer case-control study was conducted in 11 counties of southeastern Michigan. A total of 411 cases and 566 controls provided drinking water and toenail samples and answered questions about lifestyle and residential history. Uranium was measured in drinking water and toenails, and its association with bladder cancer was assessed via unconditional logistic regression models. Median uranium concentration in water was 0.12 μg L -1 , with a maximum of 4.99 μg L -1 , and median uranium concentration in toenails was 0.0031 μg g -1 . In adjusted regression models, there was a suggestion of a protective effect among those exposed to the upper quartile of uranium in drinking water (HR = 0.64, 95% CI: 0.43, 0.96) and toenails (HR 0.66; 95% CI 0.45, 0.96) compared to those in the lowest quartile. Our objective is to investigate additional adjustment of drinking water source at home residence at time of recruitment to address potential selection bias and confounding attenuated results toward the null for drinking water uranium (HR = 0.68, 95% CI: 0.44, 1.05) and toenail uranium (HR = 0.80, 95% CI: 0.53, 1.20). This case-control study showed no increased risk of bladder cancer associated with uranium found in drinking water or toenails.

Graphene-based nanomaterials for the removal of emerging contaminants of concern from water and their potential adaptation for point-of-use applications

Considering the plethora of work on the exceptional environmental performance of 2D nanomaterials, there is still a missing link in addressing their practical application in point-of-use (POU) water treatment. By reviewing the exceptional environmental performance of 2D nanomaterials with specific emphasis on graphene and its derivatives, this review aims at inspiring further discussions and research in graphene-based POU water treatment with particular focus on the removal of emerging contaminants of concern (ECCs), which is largely missing in the literature. We outlined the prevalence of ECCs in the environment, their health effects both on humans and marine life, and the potential of efficiently removing them from water using three-dimensional graphene-based macrostructures to ensure ease of adsorbent recovery and reuse compared to nanostructures. Given various successful studies showing superior adsorption capacity of graphene nanosheets, we give an account of the recent developments in graphene-based adsorbents. Moreover, several cost-effective materials which can be easily self-assembled with nanosheets to improve their environmental performance and safety for POU water treatment purposes were highlighted. We highlighted the strategy to overcome challenges of adsorbent regeneration and contaminant degradation; and concluded by noting the need for policy makers to act decisively considering the conservative nature of the water treatment industry, and the potential health risks from ingesting ECCs through drinking water. We further justified the need for the development of advanced POU water treatment devices in the face of the growing challenges regarding ECCs in surface water, and the rising cases of drinking water advisories across the world.

Safeguarding drinking water: A brief insight on characteristics, treatments and risk assessment of contamination

Water pollution stands as a critical worldwide concern, bearing extensive repercussions that extend to human health and the natural ecosystem. The sources of water pollution can be diverse, arising from natural processes and human activities and the pollutants may range from chemical and biological agents to physical and radiological contaminants. The contamination of water disrupts the natural functioning of the system, leading to both immediate and prolonged health problems. Various technologies and procedures, ranging from conventional to advanced, have been developed to eliminate water impurities, with the choice depending on the type and level of contamination. Assessing risks is a crucial element in guaranteeing the safety of drinking water. Till now, research is continuing the removal of contaminates for the sake of supplying safe drinking water. The study examined physical, inorganic, organic, biological and radiological contaminants in drinking water. It looked at where these contaminants come from, their characteristics, the impact they have and successful methods used in real-world situations to clean the contaminated water. Risk assessment methodologies associated with the use of unsafe drinking water as future directives are also taken into consideration in the present study for the benefit of public concern. The manuscript introduces a comprehensive study on water pollution, focusing on assessing and mitigating risks associated with physical, inorganic, organic, biological and radiological contaminants in drinking water, with a novel emphasis on future directives and sustainable solutions for public safety.

A deeper understanding about the role of uranium toxicity in neurodegeneration

Natural deposits and human-caused releases of uranium have led to its contamination in the nature. Toxic environmental contaminants such as uranium that harm cerebral processes specifically target the brain. Numerous experimental researches have shown that occupational and environmental uranium exposure can result in a wide range of health issues. According to the recent experimental research, uranium can enter the brain after exposure and cause neurobehavioral problems such as elevated motion related activity, disruption of the sleep-wake cycle, poor memory, and elevated anxiety. However, the exact mechanism behind the factor for neurotoxicity by uranium is still uncertain. This review primarily aims on a brief overview of uranium, its route of exposure to the central nervous system, and the likely mechanism of uranium in neurological diseases including oxidative stress, epigenetic modification, and neuronal inflammation has been described, which could present the probable state-of-the-art status of uranium in neurotoxicity. Finally, we offer some preventative strategies to workers who are exposed to uranium at work. In closing, this study highlights the knowledge of uranium's health dangers and underlying toxicological mechanisms is still in its infancy, and there is still more to learn about many contentious discoveries.

Elevated Radium Activity in a Hydrocarbon-Contaminated Aquifer

Hydrocarbon spills that reach the subsurface can modify aquifer geochemical conditions. Biogeochemical zones typically form proximal to the source zone that include iron (Fe(III)) and manganese (Mn(III/IV)) (hydr)oxide reduction, with potential to release associated geogenic contaminants to groundwater. Here, multi-level monitoring systems are used to investigate radium (²²⁶Ra, ²²⁸Ra) activities in an aquifer contaminated with a mixture of chlorinated solvents, ketones, and aromatics occurring as a dense non-aqueous phase liquid in the source zone. ²²⁶Ra activities are up to 10 times higher than background 60 m downgradient from the source zone, where pH is lower, total dissolved solid concentrations are higher, and conditions are methanogenic. Correlations indicate that Fe and Mn (hydr)oxide reduction and sorption site competition are likely responsible for elevated Ra activities within the dissolved phase plume. ²²⁶Ra activities return to background within the Fe(III)/SO₄^2--reducing zone 600 m downgradient from the source, near the middle of the dissolved phase plume. Geochemical models indicate that sorption to secondary phases (e.g., clays) is important in sequestering Ra within the plume. Although maximum Ra activities within the plume are well below the U.S. drinking water standard, elevated activities compared to background emphasize the importance of investigating Ra and other trace elements at hydrocarbon-impacted sites.

Targeted education and outreach to neighbors of homes with high gross alpha radioactivity in domestic well water

Gross alpha, a measurement of radioactivity in drinking water, is the most frequent laboratory test to exceed primary drinking water standards among wells tested under the New Jersey Private Well Testing Act (NJ PWTA). Certain geological factors prevalent in New Jersey (NJ) are primarily responsible for the presence of radioactivity in private well drinking water and thus, many of the estimated one million private well users in NJ may be at-risk of water contamination from naturally occurring radionuclides. Neighbor-based private well outreach methodology was utilized to identify high risk wells in both northern and southern NJ regions and offer free private well testing for radionuclides. Previously tested wells with gross alpha exceeding or equal to 3.7 becquerels per liter (Bq L^-1; 100 pCi/L) were selected (n = 49) to identify neighbors (n = 406) within 152.4 m (500 feet). Invitation letters were mailed to selected neighbors and some of the previously tested high wells (n = 12) offering free water sampling for the following parameters: gross alpha (48-hour rapid test), combined radium-226 and radium-228 (Ra-226 + Ra-228), uranium-238 (U-238), radon-222 (Rn-222) and iron. Overall, 70 neighbors and 5 high PWTA wells participated in this free water testing opportunity. For neighboring wells, gross alpha results revealed 47 (67.1%) wells exceeding the gross alpha MCL of 0.555 Bq L^-1 (15 pCi/L) mainly due to radium activity in the raw/untreated water. Of those with water treatment (n = 62), 12 (19.4%) treated water samples exceeded the gross alpha MCL. Targeting neighbors of known highly radioactive wells for private well testing is an effective public health outreach method and can also provide useful insight of regional contaminant variations.

Advanced Polymeric Nanocomposite Membranes for Water and Wastewater Treatment: A Comprehensive Review

Nanomaterials have been extensively used in polymer nanocomposite membranes due to the inclusion of unique features that enhance water and wastewater treatment performance. Compared to the pristine membranes, the incorporation of nanomodifiers not only improves membrane performance (water permeability, salt rejection, contaminant removal, selectivity), but also the intrinsic properties (hydrophilicity, porosity, antifouling properties, antimicrobial properties, mechanical, thermal, and chemical stability) of these membranes. This review focuses on applications of different types of nanomaterials: zero-dimensional (metal/metal oxide nanoparticles), one-dimensional (carbon nanotubes), two-dimensional (graphene and associated structures), and three-dimensional (zeolites and associated frameworks) nanomaterials combined with polymers towards novel polymeric nanocomposites for water and wastewater treatment applications. This review will show that combinations of nanomaterials and polymers impart enhanced features into the pristine membrane; however, the underlying issues associated with the modification processes and environmental impact of these membranes are less obvious. This review also highlights the utility of computational methods toward understanding the structural and functional properties of the membranes. Here, we highlight the fabrication methods, advantages, challenges, environmental impact, and future scope of these advanced polymeric nanocomposite membrane based systems for water and wastewater treatment applications.

Environmental evaluation of radioactivity levels and associated radiation hazards in groundwater around the WIPP site

Groundwater may contain radioactive substances which can be dangerous to human health. Concentrations of natural radionuclides polonium (Po), thorium (Th), uranium (U), and radium (Ra) isotopes were measured in groundwater samples collected from different locations in the vicinity of the Waste Isolation Pilot Plant (WIPP) site in Carlsbad, New Mexico. The average values of gross activity concentrations of ²¹⁰Po, ²²⁸Th, ²³⁸U, ²³⁴U, ²²⁶Ra and ²²⁸ Ra isotopes were determined to be 1.62 Bq L^-1 in shallow groundwater and 5.88 Bq L^-1 in deep groundwater, respectively. The total radioactivity in deep groundwater was higher than that in shallow groundwater, and most of the radioactivity in the water is from ²²⁶Ra. Furthermore, the effective doses for ingestion of natural radionuclides were about 0.333 mSv y^-1 for shallow groundwater and about 1.338 mSv y^-1 for deep groundwater samples, which are higher than the World Health Organization (WHO, 2017) guideline level (0.1 mSv y^-1) for drinking water. Ra dominated the total ingestion dose, contributing 93.06 % and 75.40 % of the total effective doses to the deep and shallow groundwater, respectively. The ingrowth and decay of natural radionuclides suggested that ²²⁸Ra/²²⁶Ra ratio can be a useful indicator of the source of radioactive contamination. The radioactivity data obtained from the investigated groundwater samples can be used to establish a baseline for radioactivity levels in groundwater around the WIPP site.

Uranium Determination in Waters, Wine and Honey by Solid Phase Extraction with New Ion Imprinted Polymer

An analytical method for uranium determination in waters, wine and honey was developed based on solid phase extraction (SPE) with new ion imprinted polymer. The sorbent was synthesized using 4-(2-Pyridylazo)resorcinol (PAR) as a ligand via dispersion polymerization and characterized by SEM for morphology and shape of polymer particles and nitrogen adsorption–desorption studies for their surface area and total pore volume. The kinetic experiments performed showed that the rate limiting step is the complexation between U(VI) ions and chelating ligand PAR incorporated in the polymer matrix. Investigations by Freundlich and Langmuir adsorption isotherm models showed that sorption process occurs as a surface monolayer on homogeneous sites. The high extraction efficiency of synthesized sorbent toward U(VI) allows its application for SPE determination of U(VI) in wine and honey without preliminary sample digestion using ICP-OES as measurement method. The recoveries achieved varied: (i) between 88 to 95% for surface and ground waters, (ii) between 90–96% for 5% aqueous solution of honey, (iii) between 86–93% for different types of wine. The validity and versatility of proposed analytical methods were confirmed by parallel measurement of U in water samples using Alpha spectrometry and U analysis in wine and honey after sample digestion and ICP-MS measurement. The analytical procedure proposed for U determination in surface waters is characterized with low limits of detection/quantification and good reproducibility ensuring its application for routine control in national monitoring of surface waters. The application of proposed method for honey and wine samples analysis provides data for U content in traditional Bulgarian products.

The concentration and health risk assessment of radionuclides in the muscle of tuna fish: A worldwide systematic review and meta-analysis

Exposure to radionuclides, especially in food, can endanger the health of consumers. In this study, a systematic review and meta-analysis were performed regarding the concentration of radionuclides in tuna fish muscle. International databases including PubMed, Scopus, and Embase were searched to find articles regarding the concentration of radionuclides in tuna fish muscle from 1 January 2000 to 20 February 2021. The lowest and highest concentration of radionuclides was related to Caesium-137 (¹³⁷Cs) and Potassium-40 (⁴ K), respectively. The rank order of radionuclides based on their pooled concentration was ⁴ K (370.157 Bq/kg) > ²¹⁰Po Polonium-210 (26.312 Bq/kg) > ²¹⁰Pb (5.339 Bq/kg) > ²²⁶Ra (4.005 Bq/kg) > ¹³⁷Cs (0.415 Bq/kg). The health risk assessment based on annual effective dose indicates that consumers are at the safe range of health risk (H < 1 mSv/y). The continuous monitoring concentration of radionuclides in seafood and health risk assessment should be recommended.

Use of Biomphalaria glabrata as a bioindicator of groundwater quality under the influence of NORM

The Brazilian northeast is known to have sedimentary areas that contain minerals with anomalous concentrations of naturally occurring radioactive material (NORM). This characteristic can contribute to the elevation of natural radiation in the air, soil, and groundwater. Due to the inefficiency of drinking water distribution in this region, the use of water from wells has become essential for the population. Therefore, the objective of this research was to monitor the concentration of ²³⁸U and ²³²Th associated with biomonitoring with the species of mollusc Biomphalaria glabrata in waters of residential artesian wells, used for domestic consumption, in the municipalities of Abreu e Lima and São José do Sabugi, Brazil. To check the concentration of ²³⁸U and ²³²Th, ICP-MS was used. For biomonitoring, ecotoxicity techniques such as embryotoxicity and genotoxicity were used. The monitoring results confirmed high concentrations of natural uranium in one of the residential artesian wells, the data being above the limit allowed by the Ministry of Health of Brazil, whose study reference is the World Health Organization (WHO). The results of the bioassays showed embryotoxicity, with malformations and deaths in the exposed organisms being observed. The comet assay showed that groundwater caused changes in the mollusc's DNA, indicating genotoxicity. The bioassays suggest that embryotoxicity and genotoxicity were caused mainly by the high concentration of natural uranium. Therefore, the bioindicator B. glabrata was shown to be sensitive to the toxic effects of anomalous concentrations of NORM present in groundwater.

Uranium Exposure in American Indian Communities: Health, Policy, and the Way Forward

BACKGROUND

Uranium contamination of drinking-water sources on American Indian (AI) reservations in the United States is a largely ignored and underfunded public health crisis. With an estimated 40% of the headwaters in the western U.S. watershed, home to many AI reservation communities, being contaminated with untreated mine waste, the potential health effects have largely been unexplored. With AI populations already facing continued and progressive economic and social marginalization, higher prevalence of chronic disease, and systemic discrimination, associations between various toxicant exposures, including uranium, and various chronic conditions, need further examination.

OBJECTIVES

Uranium's health effects, in addition to considerations for uranium drinking-water testing, reporting, and mitigation in reference to AI communities through the lens of water quality, is reviewed.

DISCUSSION

A series of environmental health policy recommendations are described with the intent to proactively improve responsiveness to the water quality crisis in AI reservation communities in the United States specific to uranium. There is a serious and immediate need for better coordination of uranium-related drinking-water testing and reporting on reservations in the United States that will better support and guide best practices for uranium mitigation efforts. https://doi.org/10.1289/EHP7537.

Emerging health risks and underlying toxicological mechanisms of uranium contamination: Lessons from the past two decades

Uranium contamination is a global health concern. Regarding natural or anthropogenic uranium contamination, the major sources of concern are groundwater, mining, phosphate fertilizers, nuclear facilities, and military activities. Many epidemiological and laboratory studies have demonstrated that environmental and occupational uranium exposure can induce multifarious health problems. Uranium exposure may cause health risks because of its chemotoxicity and radiotoxicity in natural or anthropogenic scenarios: the former is generally thought to play a more significant role with regard to the natural uranium exposure, and the latter is more relevant to enriched uranium exposure. The understanding of the health risks and underlying toxicological mechanisms of uranium remains at a preliminary stage, and many controversial findings require further research. In order to present state-of-the-art status in this field, this review will primarily focus on the chemotoxicity of uranium, rather than its radiotoxicity, as well as the involved toxicological mechanisms. First, the natural or anthropogenic uranium contamination scenarios will be briefly summarized. Second, the health risks upon natural uranium exposure, for example, nephrotoxicity, bone toxicity, reproductive toxicity, hepatotoxicity, neurotoxicity, and pulmonary toxicity, will be discussed based on the reported epidemiological cases and laboratory studies. Third, the recent advances regarding the toxicological mechanisms of uranium-induced chemotoxicity will be highlighted, including oxidative stress, genetic damage, protein impairment, inflammation, and metabolic disorder. Finally, the gaps and challenges in the knowledge of uranium-induced chemotoxicity and underlying mechanisms will be discussed.

Radiological health risk assessment of drinking water and soil dust from Gauteng and North West Provinces, in South Africa

Long-lived natural radionuclides such as (²³⁸U) uranium-238, (²³²Th) thorium-232, (²²⁶Ra) radium-226 and (⁴⁰K) potassium-40 and heavy metals are normally exposed to the surface during mining activities. They enter the human body when inhaled (as dust) or ingested (by drinking contaminated water). An intake of large concentrations of these radionuclides and heavy metals can lead to health effects such as development of cancers. The aim of this work was to assess the radiological health risk due to intake of radionuclides in dust and drinking water from the West Rand gold mining area and Modiri Molema Municipality (MMM) water treatment plant. The dust samples were analyzed for radionuclides of interest using the well-type high purity Germanium detector. Water samples were collected before and after purification from the Modiri Molema Municipality water treatment plant and analyzed using the ultra-low level Liquid Scintillation Counter (LSC), to evaluate the gross alpha and beta radioactivity dose levels of the radionuclides in water. An Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to evaluate the heavy metal concentrations in the drinking water after purification at the treatment plant. The total inhalation effective dose obtained in this study was (2.71 × 10⁻¹ and 1.31 × 10⁻¹) μSv.y⁻¹ for adults and infants respectively, which is below the prescribed dose range of 5–10 μSv.y⁻¹. The mean activity concentrations of the radionuclides in air dust were found to be; ²²⁶Ra, (2.14 ± 0.82) × 10⁻⁶ (Bq.m⁻³), ²³⁸U (6.08 ± 2.17) × 10⁻⁷ (Bq.m⁻³) and ²³²Th (2.65 ± 1.1) × 10⁻⁷ (Bq.m⁻³). The activity concentration of ²²⁶Ra obtained exceeded the world average by 2 times. The Ra_eq, the external hazard (H_ex) and internal hazard (H_in) indices were calculated and the values obtained from soil were lower than the world average. However, the absorbed dose rate in air was higher than the world averages of 60 nGyh^-1. The minimum and maximum gross alpha activity obtained was 0.0041 (Bq.L⁻¹) and 0.0053 (Bq.L⁻¹) respectively, while the minimum and maximum gross beta activity obtained for water samples was 0.0083 (Bq.L⁻¹) and 0.0105 (Bq.L⁻¹) respectively. More heavy metals were detected in the first two stages of the water treatment than on the last two stages, nevertheless, their concentrations did not exceed recommended limits. The results for soil dust indicates that the windward areas might pose health risks for human population staying in the area and the activity concentration for drinking water indicate that the specific activity in the water supply after purification is below the WHO guideline limit of 0.5 (Bq.L⁻¹) for gross alpha and 1 (Bq.L⁻¹) for gross beta. The results obtained were also within the range of the South Africa Department of Water Affairs and Forestry target water quality limit of (0–1.38) (Bq.L⁻¹) for gross beta activity. Heavy metals concentrations in drinking water did not exceed the stipulated limits by USEPA and DWAF. Therefore, this water after treatment is radiologically and toxicologically safe for the members of the public.

Natural radioactivity in Brazil: a systematic review

Natural radioactivity is a public health concern worldwide. Its deleterious effects are largely associated with emitting ionizing particles which generate innumerable toxicological consequences to human being. The present study aimed to describe the research state of the art on natural radioactivity in Brazil through a systematic review limited to articles published in the twenty-first century in the PubMed, SciELO, Lilacs, and Google Scholar databases. A total of 55 research articles were considered for this purpose. Based on the collected sample types, the radiation analysis in most of the scientific reports was performed on solid samples (soil/sediment/rocks), followed by water and air. In fact, most of the available information came from geological studies. A wide range of concentrations and a variety of radionuclides have been assessed, with radium being the most cited. Most of the studies described radiation levels above the international guidelines, and consider the Brazilian territory as a high natural background radiation region (HNBR). In comparison with other HNBR areas, the scientific information about the related risks to human health is still scarce. There is uncertainty about the real impact of natural radioactivity on human health, as there is a lack of scientific information for most of the country about this issue. The analysis and comparison of the available information highlights the potential risks linked to natural radioactivity and the need to incorporate suitable environmental management policies about this issue.

Measurement of gross alpha and beta activity concentration in groundwater of Jordan: groundwater quality, annual effective dose and lifetime risk assessment

The current study was conducted to measure the activity concentration of the gross alpha and beta in 87 groundwater samples collected from the productive aquifers that constitute a major source of groundwater to evaluate the annual effective dose and the corresponding health impact on the population and to investigate the quality of groundwater in Jordan. The mean activity concentration of gross alpha and beta in groundwater ranges from 0.26 ± 0.03 to 3.58 ± 0.55 Bq L^-1 and from 0.51 ± 0.07 to 3.43 ± 0.46 Bq L^-1, respectively. A very strong relationship was found between gross alpha and beta activity concentrations. The annual effective dose for alpha and beta was found in the range of 0.32-2.40 mSv with a mean value of 0.89 mSv, which is nine times higher than the World Health Organization (WHO) recommended limit and one and half times higher than the national regulation limit. The mean lifetime risk was found to be 45.47 × 10^-4 higher than the Jordanian estimated upper-bound lifetime risk of 25 × 10^-4. The data obtained in the study would be the baseline for further epidemiological studies on health effects related to the exposure to natural radioactivity in Jordan.

Assessing the Committed Effective Dose From 226Ra in Thermal Spring Water From San Diego De Alcala, Chihuahua, Mexico

The oral administration of mineral-rich spring water is known as hydropinic treatment and is used to treat certain ailments. Health benefits are attributed to thermal spring water containing radioactive elements such as radium; this has popularized use of such radioactive water in various parts of the world, causing those who ingest it to increase their internal radiation dose. The goal of this study was to assess the activity concentrations of Ra present in the thermal spring waters of San Diego de Alcala, in the state of Chihuahua, Mexico, and to estimate the health risk posed to patients by the effective dose received from ingesting this water during hydropinic treatments. Water samples were taken from different areas of the San Diego de Alcala thermal springs, and pH, temperature, electrical conductivity, and total dissolved solids were measured. The Ra activity concentrations were measured with a liquid scintillation counter. The activity concentrations of Ra in sampled water varied from 125 to 452 mBq L with an average of 276 ± 40 mBq L. The committed effective dose from each of the Ra activity concentrations found in samples ranged from 9.80 × 10 to 4.0 × 10 mSv for hydropinic treatments being carried out in San Diego de Alcala thermal spring spas. Different treatments had different intake rates (200, 600, 1,000, and 1,500 mL d) and occurred over periods of 2 or 3 wk. According to the guidelines of the US Environmental Protection Agency, the maximum permissible amount of radium in drinking water is 185 mBq L; the Ra content in most of the collected samples exceeded this limit. The committed effective doses varied with Ra concentration and intake rate; none exceeded the World Health Organization's reference dose for drinking water of 0.1 mSv y, which is the maximum amount to which the population should be exposed.

Occurrence and Sources of Radium in Groundwater Associated with Oil Fields in the Southern San Joaquin Valley, California

Geochemical data from 40 water wells were used to examine the occurrence and sources of radium (Ra) in groundwater associated with three oil fields in California (Fruitvale, Lost Hills, South Belridge). ²²⁶Ra+²²⁸Ra activities (range = 0.010-0.51 Bq/L) exceeded the 0.185 Bq/L drinking-water standard in 18% of the wells (not drinking-water wells). Radium activities were correlated with TDS concentrations (p < 0.001, ρ = 0.90, range = 145-15,900 mg/L), Mn + Fe concentrations (p < 0.001, ρ = 0.82, range = <0.005-18.5 mg/L), and pH (p < 0.001, ρ = -0.67, range = 6.2-9.2), indicating Ra in groundwater was influenced by salinity, redox, and pH. Ra-rich groundwater was mixed with up to 45% oil-field water at some locations, primarily infiltrating through unlined disposal ponds, based on Cl, Li, noble-gas, and other data. Yet ²²⁸Ra/²²⁶Ra ratios in pond-impacted groundwater (median = 3.1) differed from those in oil-field water (median = 0.51). PHREEQC mixing calculations and spatial geochemical variations suggest that the Ra in the oil-field water was removed by coprecipitation with secondary barite and adsorption on Mn-Fe precipitates in the near-pond environment. The saline, organic-rich oil-field water subsequently mobilized Ra from downgradient aquifer sediments via Ra-desorption and Mn/Fe-reduction processes. This study demonstrates that infiltration of oil-field water may leach Ra into groundwater by changing salinity and redox conditions in the subsurface rather than by mixing with a high-Ra source.

Human exposure to uranium in South African gold mining areas using barber-based hair sampling

Uranium (U) measurements in water, soil, and food related to gold mining activities in populated areas in Gauteng Province, South Africa, suggest the possibility of exposure levels that may lead to adverse health consequences, including cancer. Theoretical considerations on pathways of human uptake of significant exposures are plausible, but few data on directly measured human exposure are available. A cross-sectional study was conducted using human measurements to compare U levels with other settings around the globe (based on literature review), to explore potential exposure variability within the province, and to test the feasibility of recruiting subjects partially coming from vulnerable and difficult-to-reach populations. Wards of potentially high (HE) and low exposure (LE) were identified. Composite hair samples representing the respective local populations were collected from regular customers of selected barber shops over a period of 1-2 months. A total of 70 U concentrations were determined in 27 composite samples from 1332 individuals. U concentrations ranged from 31 μg/kg to 2524 μg/kg, with an arithmetic mean of 192 μg/kg (standard deviation, 310 μg/kg) and a median of 122 μg/kg. Although HE wards collectively showed higher U levels than LE wards (184 vs 134 μg/kg), differences were smaller than expected. In conclusion, detected U levels were higher than those from most other surveys of the general public. The barber-based approach was an efficient hair collection approach. Composite hair samples are not recommended, due to technical challenges in measuring U, and individual hair samples are needed in follow-up studies to determine predictors of exposure.

Variance in State Protection from Exposure to NORM and TENORM Wastes Generated During Unconventional Oil and Gas Operations: Where We Are and Where We Need to Go

Radioactive materials for the medical, technological, and industrial sectors have been effectively regulated in the United States since as early as 1962. The steady increase in the exploration and production of shale gas in recent years has led to concerns about exposures to Naturally Occurring Radioactive Materials (NORM) and Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) in oil and gas waste streams. This study applied policy surveillance methods to conduct a cross-sectional fifty-state survey of law and regulations of NORM and TENORM waste from oil and gas operations. Results indicated that seventeen states drafted express regulations to reduce exposure to oil and gas NORM and TENORM waste. States with active oil and gas drilling that lack regulations controlling exposure to NORM and TENORM may leave the public and workers susceptible to adverse health effects from radiation. The study concludes with recommendations in regard to regulating oil and gas NORM and TENORM waste.

Exposure assessment of natural uranium from drinking water

The uranium concentration in the drinking water of the residents of the Jaipur and Ajmer districts of Rajasthan has been measured for exposure assessment. The daily intake of uranium from the drinking water for the residents of the study area is found to vary from 0.4 to 123.9 μg per day. For the average uranium ingestion rate of 35.2 μg per day for a long term exposure period of 60 years, estimations have been made for the retention of uranium in different body organs and its excretion with time using ICRP's biokinetic model of uranium. Radioactive and chemical toxicity of uranium has been reported and discussed in detail in the present manuscript.

Radon-222 and radium-226 occurrence in water: a review

A total of 2143 dissolved radon-222 and radium-226 activity concentrations measured together in water samples was compiled from the literature. To date, the use of such a large database is the first attempt to establish a relationship for the 226Ra–222Rn couple. Over the whole dataset, radon and radium concentrations range over more than nine and six orders of magnitude, respectively. Geometric means yield 9.82±0.73 Bq l−1 for radon and 54.6±2.7 mBq l−1 for radium. Only a few waters are in 226Ra–222Rn radioactive equilibrium, with most of them being far from equilibrium; the geometric mean of the radium concentration in water/radon concentration in water (CRa/CRn) ratio is estimated to be 0.0056±0.0004. Significant differences in radon and radium concentrations are observed between groundwaters and surface waters, on the one hand, and between hot springs and cold springs, on the other. Within water types, typical ranges of radon and radium concentrations can be associated with subgroups of waters. While the radium concentration characterizes the geochemistry of the groundwater–rock interaction, the radon concentration, in most cases, is a signal of non-mobile radium embedded in the encasing rocks. Thus, the 226Ra–222Rn couple can be a useful tool for the characterization of water and for the identification of water source rocks, shedding light on the various water–rock interaction processes taking place in the environment.

(210)Po in drinking water, its potential health effects, and inadequacy of the gross alpha activity MCL

Polonium-210 ((210)Po) is a naturally-occurring, carcinogenic member of the (238)U decay series and the granddaughter of (210)Pb. It has a half life of 138.4days and is rarely found in drinking water at levels exceeding 5mBq/L because it strongly binds to aquifer sediment. When the current US Maximum Contaminant Level (MCL) covering (210)Po was promulgated in December 2000, very little was known about its occurrence and the processes responsible for mobilizing it. More is now known about the processes that mobilize (210)Po from sediments and a review of recent occurrence data show that it may not be as rare in the US as the US Environmental Protection Agency (USEPA) thought in 2000. Worldwide, only about 2200 analyses for (210)Po in drinking water were identified, with activities exceeding 500mBq/L being found only in Finland, India, Sweden, and the US. The median of 400 (210)Po analyses from the US is 4.75mBq/L and >10% of the samples exceed 500mBq/L. Current compliance-monitoring regulations in the US essentially guarantee that (210)Po contamination will not be detected except in very contaminated wells. Major problems with the US Gross Alpha Activity MCL include the volatility of (210)Po and extended holding times and sample-compositing methods that can allow the majority of (210)Po in a sample bottle to decay before analysis. In light of new information, the radionuclide rule should be changed and direct measurements of (210)Po should be made in all public-water supply wells to rule out its presence. Much of the important biological and toxicological research on (210)Po is more than four decades old and new laboratory research using modern tools is needed. Biological and epidemiological investigations of known contaminated areas are needed to assess the effect (210)Po exposure is having on animals and humans consuming the water.

Concerted Uranium Research in Europe (CURE): toward a collaborative project integrating dosimetry, epidemiology and radiobiology to study the effects of occupational uranium exposure

The potential health impacts of chronic exposures to uranium, as they occur in occupational settings, are not well characterized. Most epidemiological studies have been limited by small sample sizes, and a lack of harmonization of methods used to quantify radiation doses resulting from uranium exposure. Experimental studies have shown that uranium has biological effects, but their implications for human health are not clear. New studies that would combine the strengths of large, well-designed epidemiological datasets with those of state-of-the-art biological methods would help improve the characterization of the biological and health effects of occupational uranium exposure. The aim of the European Commission concerted action CURE (Concerted Uranium Research in Europe) was to develop protocols for such a future collaborative research project, in which dosimetry, epidemiology and biology would be integrated to better characterize the effects of occupational uranium exposure. These protocols were developed from existing European cohorts of workers exposed to uranium together with expertise in epidemiology, biology and dosimetry of CURE partner institutions. The preparatory work of CURE should allow a large scale collaborative project to be launched, in order to better characterize the effects of uranium exposure and more generally of alpha particles and low doses of ionizing radiation.

Assessment of the Central Effects of Natural Uranium via Behavioural Performances and the Cerebrospinal Fluid Metabolome

Natural uranium (NU), a component of the earth's crust, is not only a heavy metal but also an alpha particle emitter, with chemical and radiological toxicity. Populations may therefore be chronically exposed to NU through drinking water and food. Since the central nervous system is known to be sensitive to pollutants during its development, we assessed the effects on the behaviour and the cerebrospinal fluid (CSF) metabolome of rats exposed for 9 months from birth to NU via lactation and drinking water (1.5, 10, or 40 mg·L(-1) for male rats and 40 mg·L(-1) for female rats). Medium-term memory decreased in comparison to controls in male rats exposed to 1.5, 10, or 40 mg·L(-1) NU. In male rats, spatial working memory and anxiety- and depressive-like behaviour were only altered by exposure to 40 mg·L(-1) NU and any significant effect was observed on locomotor activity. In female rats exposed to NU, only locomotor activity was significantly increased in comparison with controls. LC-MS metabolomics of CSF discriminated the fingerprints of the male and/or female NU-exposed and control groups. This study suggests that exposure to environmental doses of NU from development to adulthood can have an impact on rat brain function.

An evaluation of health risk to the public as a consequence of in situ uranium mining in Wyoming, USA

In the United States there is considerable public concern regarding the health effects of in situ recovery uranium mining. These concerns focus principally on exposure to contaminants mobilized in groundwater by the mining process. However, the risk arising as a result of mining must be viewed in light of the presence of naturally occurring uranium ore and other constituents which comprise a latent hazard. The United States Environmental Protection Agency recently proposed new guidelines for successful restoration of an in situ uranium mine by limiting concentrations of thirteen groundwater constituents: arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver, nitrate (as nitrogen), molybdenum, radium, total uranium, and gross α activity. We investigated the changes occurring to these constituents at an ISR uranium mine in Wyoming, USA by comparing groundwater quality at baseline measurement to that at stability (post-restoration) testing. Of the groundwater constituents considered, only uranium and radium-226 showed significant (p < 0.05) deviation from site-wide baseline conditions in matched-wells. Uranium concentrations increased by a factor of 5.6 (95% CI 3.6-8.9 times greater) while radium-226 decreased by a factor of about one half (95% CI 0.42-0.75 times less). Change in risk was calculated using the RESRAD (onsite) code for an individual exposed as a resident-farmer; total radiation dose to a resident farmer decreased from pre-to post-mining by about 5.2 mSv y(-1). Higher concentrations of uranium correspond to increased biomarkers of nephrotoxicity, however the clinical significance of this increase is unclear.

A Community-Driven Intervention in Tuftonboro, New Hampshire, Succeeds in Altering Water Testing Behavior

Maximum contaminant levels created by the U.S. Environmental Protection Agency under the Safe Drinking Water Act do not apply to private wells. Rather, the onus is on individual households to undertake regular water testing. Several barriers exist to testing and treating water from private wells, including a lack of awareness about both well water as a potential source of contaminants and government-recommended water testing schedules; a health literacy level that may not be sufficient to interpret complex environmental health messages; the inconvenience of water testing; the financial costs of testing and treatment; and a myriad of available treatment options. The existence of these barriers is problematic because well water can be a source of hazardous contaminants. This article describes an initiative--undertaken by the Tuftonboro (New Hampshire) Conservation Commission, with support from state agencies and a research program at Dartmouth College--to increase water testing rates in a rural region with a relatively high number of wells. The project prompted more water tests at the state laboratory in one day than in the prior six years. This suggests that community-driven, collaborative efforts to overcome practical barriers could be successful at raising testing rates and ultimately improving public health.

The neurotoxicology of uranium

The brain is a target of environmental toxic pollutants that impair cerebral functions. Uranium is present in the environment as a result of natural deposits and release by human applications. The first part of this review describes the passage of uranium into the brain, and its effects on neurological functions and cognitive abilities. Very few human studies have looked at its cognitive effects. Experimental studies show that after exposure, uranium can reach the brain and lead to neurobehavioral impairments, including increased locomotor activity, perturbation of the sleep-wake cycle, decreased memory, and increased anxiety. The mechanisms underlying these neurobehavioral disturbances are not clearly understood. It is evident that there must be more than one toxic mechanism and that it might include different targets in the brain. In the second part, we therefore review the principal mechanisms that have been investigated in experimental models: imbalance of the anti/pro-oxidant system and neurochemical and neurophysiological pathways. Uranium effects are clearly specific according to brain area, dose, and time. Nonetheless, this review demonstrates the paucity of data about its effects on developmental processes and the need for more attention to the consequences of exposure during development.

Distribution of natural and artificial radioactivity in soils, water and tuber crops

Activity concentrations of radionuclides in water, soil and tuber crops of a major food-producing area in Ghana were investigated. The average gross alpha and beta activities were 0.021 and 0.094 Bq/L, respectively, and are below the guidelines for drinking water and therefore not expected to pose any significant health risk. The average annual effective dose due to ingestion of radionuclide in water ranged from 20.08 to 53.45 μSv/year. The average activity concentration of (238)U, (232)Th, (40)K and (137)Cs in the soil from different farmlands in the study area was 23.19, 31.10, 143.78 and 2.88 Bq/kg, respectively, which is lower than world averages. The determined absorbed dose rate for the farmlands ranged from 23.63 to 50.51 nGy/year, which is within worldwide range of 18 to 93 nGy/year. The activity concentration of (238)U, (232)Th, (40)K and (137)Cs in cassava ranges from 0.38 to 6.73, 1.82 to 10.32, 17.65 to 41.01 and 0.38 to 1.02 Bq/kg, respectively. Additionally, the activity concentration of (238)U, (232)Th, (40)K and (137)Cs in yam also ranges from 0.47 to 4.89, 0.93 to 5.03, 14.19 to 35.07 and 0.34 to 0.89 Bq/kg, respectively. The average concentration ratio for (238)U, (232)Th and (40)K in yam was 0.12, 0.11 and 0.17, respectively, and in cassava was 0.11, 0.12 and 0.2, respectively. None of the radioactivity is expected to cause significant health problems to human beings.

Uranium in drinking-water: a unique case of guideline value increases and discrepancies between chemical and radiochemical guidelines

BACKGROUND

Uranium represents a unique case for an element naturally present in the environment, as its chemical guideline value in drinking water significantly increased from 2 μg/L in 1998 up to 15 μg/L in 2004 and then to 30 μg/L in 2011, to date corresponding to a multiplication factor of 15 within a period of just 13 years.

OBJECTIVES

In this commentary we summarize the evolution of uranium guideline values in drinking-water based on both radiological and chemical aspects, emphasizing the benefit of human studies and their contribution to recent recommendations. We also propose a simpler and better consistency between radiological and chemical values.

DISCUSSION

The current chemical guideline value of 30 μg/L is still designated as provisional because of scientific uncertainties regarding uranium toxicity. During the same period, the radiological guideline for (238)U increased from 4 Bq/L to 10 Bq/L while that for (234)U decreased from 4 Bq/L to 1 Bq/L. These discrepancies are discussed here, and a value of 1 Bq/L for all uranium isotopes is proposed to be more consistent with the current chemical value of 30 μg/L.

CONCLUSION

Continuous progress in the domains of toxicology and speciation should enable a better interpretation of the biological effects of uranium in correlation with epidemiological human studies. This will certainly aid future proposals for uranium guideline values.

Unexpected lack of deleterious effects of uranium on physiological systems following a chronic oral intake in adult rat

Uranium level in drinking water is usually in the range of microgram-per-liter, but this value may be as much as 100 to 1000 times higher in some areas, which may raise question about the health consequences for human populations living in these areas. Our purpose was to improve knowledge of chemical effects of uranium following chronic ingestion. Experiments were performed on rats contaminated for 9 months via drinking water containing depleted uranium (0.2, 2, 5, 10, 20, 40, or 120 mg/L). Blood biochemical and hematological indicators were measured and several different types of investigations (molecular, functional, and structural) were conducted in organs (intestine, liver, kidneys, hematopoietic cells, and brain). The specific sensitivity of the organs to uranium was deduced from nondeleterious biological effects, with the following thresholds (in mg/L): 0.2 for brain, >2 for liver, >10 for kidneys, and >20 for intestine, indicating a NOAEL (No-Observed-Adverse-Effect Level) threshold for uranium superior to 120 m g/L. Based on the chemical uranium toxicity, the tolerable daily intake calculation yields a guideline value for humans of 1350 μg/L. This value was higher than the WHO value of 30 μg/L, indicating that this WHO guideline for uranium content in drinking water is very protective and might be reconsidered.

Potential impacts of radon, terrestrial gamma and cosmic rays on childhood leukemia in France: a quantitative risk assessment

Previous epidemiological studies and quantitative risk assessments (QRA) have suggested that natural background radiation may be a cause of childhood leukemia. The present work uses a QRA approach to predict the excess risk of childhood leukemia in France related to three components of natural radiation: radon, cosmic rays and terrestrial gamma rays, using excess relative and absolute risk models proposed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Both models were developed from the Life Span Study (LSS) of Japanese A-bomb survivors. Previous risk assessments were extended by considering uncertainties in radiation-related leukemia risk model parameters as part of this process, within a Bayesian framework. Estimated red bone marrow doses cumulated during childhood by the average French child due to radon, terrestrial gamma and cosmic rays are 4.4, 7.5 and 4.3 mSv, respectively. The excess fractions of cases (expressed as percentages) associated with these sources of natural radiation are 20 % [95 % credible interval (CI) 0-68 %] and 4 % (95 % CI 0-11 %) under the excess relative and excess absolute risk models, respectively. The large CIs, as well as the different point estimates obtained under these two models, highlight the uncertainties in predictions of radiation-related childhood leukemia risks. These results are only valid provided that models developed from the LSS can be transferred to the population of French children and to chronic natural radiation exposures, and must be considered in view of the currently limited knowledge concerning other potential risk factors for childhood leukemia. Last, they emphasize the need for further epidemiological investigations of the effects of natural radiation on childhood leukemia to reduce uncertainties and help refine radiation protection standards.

Occurrence of ²¹⁰Po and biological effects of low-level exposure: the need for research

BACKGROUND

Polonium-210 (²¹⁰Po) concentrations that exceed 1 Bq/L in drinking-water supplies have been reported from four widely separated U.S. states where exposure to it went unnoticed for decades. The radionuclide grandparents of ²¹⁰Po are common in sediments, and segments of the public may be chronically exposed to low levels of ²¹⁰Po in drinking water or in food products from animals raised in contaminated areas.

OBJECTIVES

We summarized information on the environmental behavior, biokinetics, and toxicology of ²¹⁰Po and identified the need for future research.

METHODS

Potential linkages between environmental exposure to ²¹⁰Po and human health effects were identified in a literature review.

DISCUSSION

²¹⁰Po accumulates in the ovaries where it kills primary oocytes at low doses. Because of its radiosensitivity and tendency to concentrate ²¹⁰Po, the ovary may be the critical organ in determining the lowest injurious dose for ²¹⁰Po. ²¹⁰Po also accumulates in the yolk sac of the embryo and in the fetal and placental tissues. Low-level exposure to ²¹⁰Po may have subtle, long-term biological effects because of its tropism towards reproductive and embryonic and fetal tissues where exposure to a single alpha particle may kill or damage critical cells. ²¹⁰Po is present in cigarettes and maternal smoking has several effects that appear consistent with the toxicology of ²¹⁰Po.

CONCLUSIONS

Much of the important biological and toxicological research on ²¹⁰Po is more than four decades old. New research is needed to evaluate environmental exposure to ²¹⁰Po and the biological effects of low-dose exposure to it so that public health officials can develop appropriate mitigation measures where necessary.