External Exposure Research Articles

Creation of Equipment for Testing Roofs for Resistance to External Fire Influence

This paper examines and analyzes the domestic and foreign regulatory framework, guidelines and technical documents, information brochures, manuals, handbooks, test reports and other literary sources as well as information on the Internet. In the countries of the European space, fire safety requirements have been established for roofs and roofing materials, both for roofing materials and for roofs as part of structures, which helps to limit the spread of fire in buildings and structures during a fire. It has been proven that there is a need to create equipment for testing resistance to external fire exposure in accordance with DSTU CEN/TS 1187:2016 (method 2) of coverings of buildings (roofs) and establishing fire classification according to DSTU EN 13501-5:2016. A registration certificate, a technical description, an operating manual, and a program and methodology of the test bench verification have been developed. The initial verification of the test bench was carried out and it was put into operation. Approbation of the test method was carried out on the created test bench through experimental studies of five types of roofing materials being widely used on construction works in Ukraine using two bases (substrates) of combustible and non-combustible materials at air flow speeds of 2 m/s and 4 m/s above the specimen surface. According to the results of this work, it was established that the maximum relative deviation of the result of measuring the length of the damaged (charred) part of the specimens was in the range of 1.2 % to 23.3 % for the roof and 0.7 % to 27.5 % for the base.

Assessing radiation dosimetry for microorganisms in naturally radioactive mineral springs using GATE and Geant4-DNA Monte Carlo simulations.

Mineral springs in Massif Central, France can be characterized by higher levels of natural radioactivity in comparison to the background. The biota in these waters is constantly under radiation exposure mainly from the α-emitters of the natural decay chains, with 226Ra in sediments ranging from 21 Bq/g to 43 Bq/g and 222Rn activity concentrations in water up to 4600 Bq/L. This study couples for the first time micro- and nanodosimetric approaches to radioecology by combining GATE and Geant4-DNA to assess the dose rates and DNA damages to microorganisms living in these naturally radioactive ecosystems. It focuses on unicellular eukaryotic microalgae (diatoms) which display an exceptional abundance of teratological forms in the most radioactive mineral springs in Auvergne. Using spherical geometries for the microorganisms and based on γ-spectrometric analyses, we evaluate the impact of the external exposure to 1000 Bq/L 222Rn dissolved in the water and 30 Bq/g 226Ra in the sediments. Our results show that the external dose rates for diatoms are significant (9.7 μGy/h) and comparable to the threshold (10 μGy/h) for the protection of the ecosystems suggested by the literature. In a first attempt of simulating the radiation induced DNA damage on this species, the rate of DNA Double Strand Breaks per day is estimated to 1.11E-04. Our study confirms the significant mutational pressure from natural radioactivity to which microbial biodiversity has been exposed since Earth origin in hydrothermal springs.

Response of current dosemeters to new operational quantities in rotational geometry.

Recently, the ICRU released Report 95, where new operational quantities for external radiation exposure are defined. The new quantities are defined in close relation to the protection quantities. This change affects the practice use of dosemeters. That is why the instruments must be adapted to the measurement of new quantities before their implementing as legally binding. The discrepancies depend on radiation spectra-particle type, energy of particles and direction of incidence. To analyse the performance of currently used instruments, irradiations in photon and neutron fields of various energies were performed for personal and area dosemeters. In this work, the response of photon and neutron personal dosemeters in conditions of rotational geometry is presented. The difference between the responses with respect to the new or old operational quantity was not large, which corresponded to the similar reference values for this irradiation geometry. The mutual ratio depended on the specific radiation quality and geometry. The behaviour of different types of dosemeters varied too.

Development of a dose estimation system for external exposure assessment at the late phase for individuals living in areas affected by the Fukushima nuclear accident.

Although the elevated ambient dose equivalent (ADE) rates in areas radiologically affected by the 2011 Fukushima nuclear plant accident decreased as time passed, the assessment of Fukushima residents' external dose is still important. A dose estimation system for external exposure assessment at the late phase for individuals living in Fukushima Prefecture was developed for this purpose. The developed system enables the estimations of external doses over the future based on an individual behavioral pattern and ADE-rate distributions from aerial monitoring data and its predicted ADE rate. To validate the system, the estimated results were compared with the measured readings of personal dosemeters. The results indicate that the developed system properly reproduced the individual external doses of subjects living in areas where the outdoor ADE rates exceeded 0.2μSvh-1.

Assessment of the clinical and hematological status in acute radiation damage of Leningrad calico chickens

The problem of radiation damage to the human body, animals, birds and its individual systems and organs against the background of the use of ionizing radiation sources has acquired relevance throughout the world over the past decades. In the event of an emergency, acute radiation damage in poultry will be massive and increase the risks of developing infectious and noninfectious diseases, due to a decrease in the level of specific resistance, low effectiveness of therapeutic and preventive measures and, as a result, will lead to a decrease in the quality of the resulting product. In view of this, studies aimed at studying the features of the course of radiation pathology in chickens are very relevant and will be taken into account when developing and applying radioprotective formulations.The study of the features of the course of acute radiation damage caused by uniform single irradiation at doses of 7 Gy; 9 Gy; 11 Gy and 13 Gy, at a power of 0.99 Gy/min, was carried out on Leningrad calico chickens. Resistance to ionizing radiation was assessed by generally accepted clinical and hematological methods. Pronounced changes in clinical manifestations and shifts in morphological parameters of peripheral blood were noted under the influence of gamma radiation. Thus, irradiation of chickens with doses of 11 Gy and 13 Gy caused the development of acute radiation damage of an extremely severe degree, which led to severe depression, refusal of feed, shortening the duration or absence of a latent period, against the background of severe leuko- and erythropenia. Irradiation with a dose of 9 Gy caused severe acute radiation damage characterized by adynamia, reduced feed intake, diarrhea with an admixture of blood. Leukopenia was noted in the blood, which by day 12 values were lower than before irradiation by 41.9% and erythropenia. During acute radiation damage in chickens, when irradiated at a dose of 7 Gy, the development of the initial, latent, peak and recovery period in the surviving individuals was clearly traced. The clinical manifestation was characterized by a complex of dyspeptic and neuromotor disorders, moderate leukopenia was noted in the blood. In all experimental chickens, a violation of egg production was noted, up to complete cessation against the background of irradiation at doses of 11 Gy and 13 Gy. It is concluded that uniform single irradiation of chickens in doses from 7 Gy to 13 Gy leads to acute radiation damage and negatively affects the productive qualities of poultry. In order to conduct the experiment on the principle of pairs of analogues, 5 groups of animals were formed, 10 chickens in each. Determination of the content of erythrocytes, leukocytes and platelets in the blood was determined by counting in the Goryaev chamber. External total single exposure to gamma radiation at doses of 7 Gy, 9 Gy, 11 Gy and 13 Gy led to the development of acute radiation exposure of medium, severe and extremely severe degrees, respectively.

Investigation of the relationship between heavy metals in the blood and depression in people with different body mass indices using the NHANES database: A cross-sectional study

BackgroundExposure to heavy metals considered a major risk factor for mental health. ObjectiveExamining how heavy metals in blood are associated with depression in individuals of various body mass indexes. MethodsA total sample of 15,560 individuals was screened, with 4355 participants finally enrolled to study. The PHQ-9 was used to assess participants' depressive symptoms. ResultsA logistic regression analysis was used to investigate the relationship between the levels of heavy metals in the blood and the depression. Serum cadmium levels were found to be associated with risk of depression, with an odds ratio of 2.247 (95 % CI: 1.584–3.244). However, no significant correlations were observed between depression and blood levels of lead, selenium, and manganese. Subgroup analysis was performed and found that higher Cd concentrations were associated with a greater risk of depression at the same BMI. With the same Cd concentration, the risk of depression was lowest when participants' BMI was ≥30 kg/m2 and increased with increasing BMI when participants' BMI was <30 kg/m2. LimitationsIt is not possible to analyze the effect of external exposure to Cd. ConclusionCd in blood may be positively correlated with depression in American adults, and the effect of this trend is different in people with different body mass indices. With the increase in BMI, the risk gradually rises. However, it is lowest among obese people.

Evaluation of natural radioactivity in the soil surrounding Bhabha Atomic Research Centre, Visakhapatnam, Andhra Pradesh, India

Abstract Activity concentrations of naturally occurring radionuclides in soil samples collected during 2013–2018 from different 53 locations around Bhabha Atomic Research Centre (BARC), Visakhapatnam, Andhra Pradesh, India, were determined using high-purity germanium gamma-ray spectrometry. An R and D center of BARC is upcoming at Visakhapatnam, North coastal Andhra Pradesh. The annual effective dose (AED) and the radiation indices from the soil activity were evaluated to generate the baseline data for this area. The average activity concentrations of the naturally occurring radionuclides 238U, 226Ra, 232Th, and 40K in the soil samples studied are 29 ± 8 Bq/kg, 31 ± 1 Bq/kg, 188 ± 2 Bq/kg, and 471 ± 10 Bq/kg, respectively. The concentration of 226Ra and 40K in the collected samples is comparable with the world average concentrations of 33 Bq/kg and 420 Bq/kg, however, 232Th is observed to be higher than the world average of 45 Bq/kg. AED due to external terrestrial radiation from the region studied is in the range the range 0.37 to 2.5 mSv/y with an average of 0.9 mSv/y. The mean radium equivalent activity values for around 70% of the studied samples are lower than the permitted levels of 370 Bq/kg. The mean external exposure index has been determined to be around the safe criterion limit of unity. The mean value of the representative level index Iϒ is 2.4. Higher values in some locations are due to thorium in monazite deposits. This report will be useful as preoperational study to evaluate the impact on the environment due to ongoing and future man-made developments.

Adopting a child perspective for exposome research on mental health and cognitive development - Conceptualisation and opportunities.

Mental disorders among children and adolescents pose a significant global challenge. The exposome framework covering the totality of internal, social and physical exposures over a lifetime provides opportunities to better understand the causes of and processes related to mental health, and cognitive functioning. The paper presents a conceptual framework on exposome, mental health, and cognitive development in children and adolescents, with potential mediating pathways, providing a possibility for interventions along the life course. The paper underscores the significance of adopting a child perspective to the exposome, acknowledging children's specific vulnerability, including differential exposures, susceptibility of effects and capacity to respond; their susceptibility during development and growth, highlighting neurodevelopmental processes from conception to young adulthood that are highly sensitive to external exposures. Further, critical periods when exposures may have significant effects on a child's development and future health are addressed. The paper stresses that children's behaviour, physiology, activity pattern and place for activities make them differently vulnerable to environmental pollutants, and calls for child-specific assessment methods, currently lacking within today's health frameworks. The importance of understanding the interplay between structure and agency is emphasized, where agency is guided by social structures and practices and vice-versa. An intersectional approach that acknowledges the interplay of social and physical exposures as well as a global and rural perspective on exposome is further pointed out. To advance the exposome field, interdisciplinary efforts that involve multiple scientific disciplines are crucial. By adopting a child perspective and incorporating an exposome approach, we can gain a comprehensive understanding of how exposures impact children's mental health and cognitive development leading to better outcomes.

Assessment of exposure to pesticides: residues in 24 h duplicate diets versus their metabolites in 24 h urine using suspect screening and target analysis

Human biomonitoring can add value to chemical risk assessment by reducing the assumptions regarding consumption rates, residue occurrence, and processing effects and by integrating exposures from different sources (diet, household use, environmental). However, the relationship between exposure and concentration in human matrices is unknown for most pesticides. Therefore, we conducted a pilot study to gain more insight into the qualitative and quantitative relationship between dietary intake of pesticides (external exposure) and urinary excretion (reflecting internal exposure). In this cross-sectional observational study, 35 healthy consumers aged 18–65 years from the region of Wageningen, Netherlands, collected an exact duplicate portion of their diets during 24 h. On the same day, they also collected all their urine. The duplicate diets were analyzed using target screening by GC- and LC-HRMS; each duplicate diet contained at least five, up to 21, pesticide residues. The 24 h urine samples were analyzed using LC-HRMS in a suspect screening workflow. Metabolites were tentatively detected in all 24 h urine samples, ranging from six metabolites corresponding to four pesticides up to 40 metabolites originating from 16 pesticides in a single urine sample. In total, 65 metabolites originating from 28 pesticides were tentatively detected. After prioritization and additional confirmation experiments, 28 metabolites originating from 10 pesticides were identified with confidence level 1 or 2b. Next, quantitative analysis was performed for a selection of pesticides in duplicate diets and their metabolites in 24 h urine to assess quantitative relationships. In the quantitative comparisons between duplicate diet and 24 h urine, it was found that some metabolites were already present in the duplicate diet, which may give an overestimation of exposure to the parent pesticide based on measurement of the metabolites in urine. Additionally, the quantitative comparisons suggest a background exposure through other exposure routes. We conclude that suspect screening of 24 h urine samples can disclose exposure to mixtures of pesticide on the same day in the general population. However, more research is needed to obtain quantitative relationships between dietary intake and exposure.Graphical

Comparison of prenatal and postnatal exposure to endocrine active phenol derivatives in mammals — Humans and Baltic grey seals

Bisphenol A (BPA), 4-tert-octylphenol (4-t-OP), and 4-nonylphenol (4-NP) are characterised by their endocrine active properties. Their negative effects on the development of the body are doubly important in the reproduction process. The goal was to compare the maternal transfer of phenol derivatives in humans and seals and identify factors that may affect the load of phenol derivatives entering the mother's body, which translates into a risk to the offspring. Phenol derivatives were determined using HPLC-FLD. It was shown that higher concentrations of phenol derivatives in blood or milk were detected in humans (mothers and newborns) compared to concentrations in Baltic seals. This was influenced by external exposure factors, i.e., leaching of phenol derivatives from food packaging or dermal contact. The authors conclude that milk is the main component in the maternal transfer of BPA to the next generation in humans, while blood is a carrier of alkylphenols, particularly 4-tert-octylphenol.

Unraveling the contribution of dietary intake to human phthalate internal exposure

Human exposure to phthalates (PAEs) occurs primarily through diet, but the contribution of dietary exposure to the total internal exposure of PAEs has not been well studied. This work investigated the relationship between dietary exposure and human internal exposure to PAEs. Daily food samples were determined to evaluate the health risk of dietary exposure, and phthalate metabolites (mPAEs) were determined from urine samples of 360 volunteers of Guangzhou to assess their internal exposure. The total mPAEs concentration in the urine samples ranged from 8.43 to 1872 ng/mL, with mono-(2-ethylhexyl) phthalate (MEHP), mono-n-butyl phthalate (MnBP), and mono-isobutyl phthalate (MiBP) being the most predominant mPAEs. The concentration of PAEs in food ranged from n.d-40200 μg/kg, and benzyl butyl phthalate (BBzP), di-n-butyl phthalate (DnBP) and di-(2-ethylhexyl) phthalate (DEHP) were the most prevalent. PAE exposure was significantly associated with age, and children exhibited the highest concentration of mPAEs. Using Monte Carlo simulation to estimate PAE exposure's health risk eliminated uncertainties caused by single-point sampling and provided more reliable statistical results. The hazard quotient (HQ) was used to evaluate PAE exposure health risks. The results showed that 37% of the volunteers had HQ levels higher than 1 based on urinary mPAE concentrations, while 24% of the volunteers had HQ levels greater than 1 because of dietary exposure to PAEs. Dietary intake was the predominant exposure route for PAEs, and accounted for approximately 65% (24% out of 37%) of the cases where HQ levels exceeded 1.The work revealed the correlation between dietary external and internal exposure to PAEs, and further studies are needed to better understand the implications.

Twenty-two years later: consistent dose estimation of an accidental overexposure by retrospective biological dosimetry.

The goal of this study was to retrospectively estimate the exposure dose of a victim from the Lilo radiological accident in Georgia after 22 y and compare it with the original cytogenetics-based analysis performed in our laboratory. Similar types of studies have been published, notably involving victims of the Chernobyl, Goiânia and Tammiku accidents. Nevertheless, their estimations were done after shorter periods of time post-exposure, and in some cases, the exposure might not have been exclusively of an external nature. In this study, Fluorescence In Situ Hybridization (FISH) was used to score chromosomal translocations in lymphocytes from a recent blood sample of the victim and the dose assessment was performed using our laboratory's FISH calibration curve. The resulting whole-body exposure dose of 0.35Gy [0.12, 0.72] was similar to the one obtained when reanalysing the original scoring data from 1997 (0.38Gy [0.13-0.75]), suggesting that our current calibration curve could be used for relative dose estimations long time after external exposure.

Relatively low fluoride in drinking water increases risk of knee osteoarthritis (KOA): a population-based cross-sectional study in China.

Previous studies indicate that fluoride in drinking water has a toxic effect on cartilage and skeleton, which triggers osteoarthritis (OA) of which the most frequent is knee OA (KOA). A cross-sectional study was conducted to assess the association between fluoride exposure and KOA among 1128 subjects. Water fluoride (WF) and urinary fluoride (UF) were chosen as external exposure (internal exposure) of fluoride. Logistic regression analysis showed that an increased fluoride exposure was a risk factor for KOA (WF: OR = 1.318, 95% CI 1.162-1.495, p < 0.001; UF: OR = 1.210, 95% CI 1.119-1.310, p < 0.001). After adjusting for covariates, the risk of KOA in the 4th quartile (Q) of WF was twice that of the 1st Q (OR = 2.079, 95% CI 1.448-2.986, p < 0.001). The risks of KOA in the 2nd Q, 3rd Q and 4th Q of UF were 1.6, 1.5, and 2.9 times higher than in the 1stQ (OR = 1.597, 95% CI 1.066-2.393, p = 0.023; OR = 1.560, 95% CI 1.043-2.333, p = 0.030; OR = 2.897, 95% CI 1.957-4.288, p < 0.001). The population aged < 60 exposed to the 4th Q of WF (or UF) had a higher risk than the population exposed to the 1st Q of WF (or UF) (ORWF = 1.958, 95% CI 1.249-3.070, p = 0.003; ORUF = 2.923, 95% CI 1.814-4.711, p < 0.001). With increasing UF by Q, the male had a risk of KOA. In conclusion, excessive fluoride dose in drinking water could increase the risk of KOA. Especially, the population with aged < 60, male and obesity more likely to having KOA when they exposed to same higher fluoride.

Development of a Generic PBK Model for Human Biomonitoring with an Application to Deoxynivalenol.

Toxicokinetic modelling provides a powerful tool in relating internal human exposure (i.e., assessed through urinary biomarker levels) to external exposure. Chemical specific toxicokinetic models are available; however, this specificity prevents their application to similar contaminants or to other routes of exposure. For this reason, we investigated whether a generic physiological-based kinetic (PBK) model might be a suitable alternative for a biokinetic model of deoxynivalenol (DON). IndusChemFate (ICF) was selected as a generic PBK model, which could be fit for purpose. Being suited for simulating multiple routes of exposure, ICF has particularly been used to relate the inhalation and dermal exposure of industrial chemicals to their urinary excretion. For the first time, the ICF model was adapted as a generic model for the human biomonitoring of mycotoxins, thereby extending its applicability domain. For this purpose, chemical-specific data for DON and its metabolites were collected directly from the literature (distribution and metabolism) or indirectly (absorption and excretion) by fitting the ICF model to previously described urinary excretion data. The obtained results indicate that this generic model can be used to model the urinary excretion of DON and its glucuronidated metabolites following dietary exposure to DON. Additionally, the present study establishes the basis for further development of the model to include an inhalation exposure route alongside the oral exposure route.

A Systematic Review of Polycyclic Aromatic Hydrocarbon Derivatives: Occurrences, Levels, Biotransformation, Exposure Biomarkers, and Toxicity.

Polycyclic aromatic hydrocarbon (PAH) derivatives constitute a significant class of emerging contaminants that have been ubiquitously detected in diverse environmental matrixes, with some even exhibiting higher toxicities than their corresponding parent PAHs. To date, compared with parent PAHs, fewer systematic summaries and reanalyses are available for PAH derivatives with great environmental concerns. This review summarizes the current knowledge on the chemical species, levels, biotransformation patterns, chemical analytical methods, internal exposure routes with representative biomarkers, and toxicity of PAH derivatives, primarily focusing on nitrated PAHs (NPAHs), oxygenated PAHs (OPAHs), halogenated PAHs (XPAHs), and alkylated PAHs (APAHs). A collection of 188 compounds from four categories, 44 NPAHs, 36 OPAHs, 56 APAHs, and 52 XPAHs, has been compiled from 114 studies that documented the environmental presence of PAH derivatives. These compounds exhibited weighted average air concentrations that varied from a lower limit of 0.019 pg/m3 to a higher threshold of 4060 pg/m3. Different analytical methods utilizing comprehensive two-dimensional gas chromatography coupled with high-resolution time-of-flight mass spectrometry (GC × GC-TOF-MS), gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS), comprehensive two-dimensional gas chromatography coupled to quadrupole mass spectrometry (GC × GC-QQQ-MS), and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), that adopted untargeted strategies for the identification of PAH derivatives are also reviewed here. Additionally, an in-depth analysis of biotransformation patterns for each category is provided, including the likelihood of specific biotransformation reaction types. For the toxicity, we primarily summarized key metabolic activation pathways, which could result in the formation of reactive metabolites capable of covalently bonding with DNA and tissue proteins, and potential health outcomes such as carcinogenicity and genotoxicity, oxidative stress, inflammation and immunotoxicity, and developmental toxicity that might be mediated by the aryl hydrocarbon receptor (AhR). Finally, we pinpoint research challenges and emphasize the need for further studies on identifying PAH derivatives, tracking external exposure levels, evaluating internal exposure levels and associated toxicity, clarifying exposure routes, and considering mixture exposure effects. This review aims to provide a broad understanding of PAH derivatives' identification, environmental occurrence, human exposure, biotransformation, and toxicity, offering a valuable reference for guiding future research in this underexplored area.

Assessments of annual effective doses for population and estimation of environmental risk in the vicinity of coal-fired power plant Kakanj, Bosnia and Herzegovina

The paper describes radioactivity monitoring and radiological risk assessment procedures for the population and the environment in three villages located around the coal-fired power plant. The dose assessments were performed after long-term radioactivity monitoring that was carried out in the production process and in the vicinity of the coal-fired power plant Kakanj, Bosnia and Herzegovina.The estimated annual effective doses for the population living in the observed villages were in the range of 1.89–2.13 mSv. The most significant contributions were delivered from ingestion of food and water (0.55–0.63 mSv y−1); external exposure from building materials (0.44–0.62 mSv y−1) and inhalation of radon (222Rn) progeny (0.29–0.62 mSv y−1).The inhalation doses from flying radionuclide particles were not significant with values in the range of 0.0056–0.0062 mSv y−1 for inhalation of 235U, 238U, 226Ra, and 232Th. External terrestrial doses were in the range of average world values (0.070–0.094 mSv y−1).Environmental risk was estimated using the ERICA tool which did not highlight any threatened species. A conservative approach with a lower dose screening value (10 nGy h−1) indicated the risk for lichens and bryophytes as terrestrial organisms with high accumulation capacity for natural radionuclides.

Early-life risk factors for food allergy: Dietary and environmental factors revisited.

There appears a steep increase in the prevalence of food allergy worldwide in the past few decades. It is believed that, rather than genetic factors, the recently altered dietary and environmental factors are the driving forces behind the rapid increase of this disease. Accumulating evidence has implied that external exposures that occurred in prenatal and postnatal periods could affect the development of oral tolerance in later life. Understanding the potential risk factors for food allergy would greatly benefit the progress of intervention and therapy. In this review, we present updated knowledge on the dietary and environmental risk factors in early life that have been shown to impact the development of food allergy. These predominantly include dietary habits, microbial exposures, allergen exposure routes, environmental pollutants, and so on. The key evidence, conflicts, and potential research topics of each theory are discussed, and associated interventional strategies to prevent the disease development and ameliorate treatment burden are included. Accumulating evidence has supported the causative role of certain dietary and environmental factors in the establishment of oral tolerance in early life, especially the time of introducing allergenic foods, skin barrier function, and microbial exposures. In addition to certain immunomodulatory factors, increasing interest is raised toward modern dietary patterns, where adequately powered studies are required to identify contributions of those modifiable risk factors. This review broadens our understanding of the connections between diet, environment, and early-life immunity, thus benefiting the progress of intervention and therapy of food allergy.

Partial Extraction Therapy (Part 2): Complication Management in Full-Arch Dental Implant Therapy.

Partial extraction therapy (PET) is a group of surgical techniques that preserves the periodontium and peri-implant tissues during restorative and implant therapy by conserving a portion of the patient's own root structure to maintain blood supply derived from the periodontal ligament complex. PET includes the socket shield technique (SST), proximal shield technique (PrST), pontic shield (PtST), and root submergence technique (RST). Although their clinical success and benefits have been demonstrated, several studies report possible complications. The focus of this article is to highlight management strategies for the most common complications associated with PET including internal root fragment exposure, external root fragment exposures, and root fragment mobility.

Radiation Safety and External Radiation Exposure Rate of Patients Receiving I-131 Therapy for Hyperthyroidism and Remnant Ablation as Outpatient: An Institutional Experience.

Objective Our objective was to study the radiation exposure rate as function of time in the administration of radioiodine iodine-131 (I-131) for the treatment of thyrotoxicosis or Graves' disease and remnant ablation on an outpatient basis at the Department of Nuclear Medicine, and also, to study the impact of revised discharge criteria for radioiodine therapy enforced by the Atomic Energy Regulatory Board (AERB) of India. Materials and Methods This study included patients who underwent low-dose radioiodine therapy using I-131. Patients were classified into two different groups, that is, group A and group B. Group A included patients receiving low dose I-131 for the treatment of thyrotoxicosis, whereas group B included patients receiving I-131 therapy for the ablation of residual thyroid tissue after total thyroidectomy. The radiation exposure rate was measured using a radiation detector in milli roentgen per hour (mR/h) at 5 cm distance of stomach and neck levels and with the patient standing at the distance of 1 m after oral administration of I-131 at 0, 1, and 2 hours. Results A total of 134 (17 males and 117 females) patients were included in the study. Group A comprised 102 (14 male and 88 females) patients and group B of 32 (3 males and 29 females) patients. At the neck level, the average exposure rate in group A versus group B after 0, 1, and 2 hours was observed to be 6.9 versus 22.27 mR/h, 33.67 versus 43.39 mR/h, and 41.75 versus 48.90 mR/h, respectively. At the stomach level, the exposure rate was 23.65 versus 71.32 mR/h, 13.27 versus 48.45 mR/h, and 9.91 versus 39.43 mR/h after 0, 1, and 2 hours, respectively. At a distance of 1 m, the exposure rate was 1.31 versus 2.99 mR/h, 1.05 versus 2.58 mR/h, and 0.92 versus 2.21 mR/h, respectively. Conclusion Exposure rate measured for patients treated with up to 1,110 MBq (30 mCi) of I-131 was under permissible limits as per revised discharged limits, that is, 50 µSv/h (5 mR/h) prescribed by AERB, India. The patients undergoing radioiodine therapy I-131 (up to 1,110 MBq/30 mCi) can be discharged safely 2 hours postadministration following good work practice along with providing proper radiation safety instructions to patients.

New operational quantities (RBE × D p lens/Φ) for eye lens neutron dosimetry as a function of energy and angle of incidence in the ICRU 95 formalism

This paper is a continuation of a study published recently by the authors. It presents and discusses computed personal absorbed dose in the lens of the eye (D p lens/Φ), and a relative biological effectiveness (RBE)-weighted absorbed dose (in terms of an newly proposed operational quantity RBE × D p lens/Φ), conversion coefficients for the lens of the eye for neutron exposure at incident energies from thermal to ∼20 MeV and at angles of incidence from 0° to 90° in 15° increments, at 180° and for rotational incidence irradiation geometry (from 0° to 360° in 5° increments). These conversion coefficients were obtained from a simulation model developed for this study that contains the stylised eye model, embedded in the adult UF-ORNL mathematical phantom, whereby the previously stated RBE-weighted absorbed dose was obtained using the proposed RBE versus neutron energy distribution compiled in a previous paper by the authors. The simulations carried out for this study using the Monte Carlo N-Particle transport code version 6.2, were conducted in a realistic human eye model, for the left and right sensitive and whole volume of the lens of the eye, considering the recent proposed redefinition of the operational quantities for external radiation exposure in International Commission on Radiation Units and Measurements (ICRU) report 95. A comprehensive set of tabulated data for neutron fluence-to-dose conversion coefficients (D p lens/Φ in pGy cm2) and RBE-weighted absorbed dose (RBE × D p lens/Φ in pGy cm2) conversion coefficients is included in this paper as a function of incident neutron energy and angle of incidence. Data for D p lens/Φ (pGy cm2) are compared to similar data from the literature for validation of our model. Data for RBE × D p lens/Φ (in pGy cm2), were also compared to the equivalent operational quantity H p(3,α)/Φ (in pSv cm2) conversion coefficients calculated at 3 mm depth in a cylindrical phantom for different incident neutron energies and angles of incidence from 0° to 75° in 15° increments to demonstrate the relevance of this newly proposed operational quantity for doses resulting in tissue reactions (deterministic effects) which should be quoted in Gray (RBE-weighted absorbed dose, RBE × D (Gy)), rather than Sievert (Sv) which is reserved for stochastic effects. The current neutron weighted absorbed dose (RBE × D p lens) is proposed for the tissue reactions in the eye-lens for neutron radiation as per National Council on Radiation Protection and Measurements report 180 and in line with the recent proposal for the review and revision of the System of Radiological Protection to Keeping the International Commission on Radiological Protection (ICRP) recommendations fit for purpose. This method would bring better alignment between the dose limits in ICRP 118 and the new operational quantity consistent with the units of the new eye-lens dose limits without being overly conservative. The utilization of the proposed new operational quantities, as outlined in ICRU 95, has the potential to address the ongoing challenge in enforcing regulatory limits for neutron eye dose, specifically the use of Gy instead of Sv. It should be noted that the applicability of this will vary from country to country as in many countries the legislation is likely to mandate the use of H p(3) until the regulation is amended. This approach can serve as an interim solution while awaiting the issuance of the new ICRP general recommendations, which is expected to take several years. Implementing the new operational quantities can contribute to enhancing the accuracy and effectiveness of neutron eye dose limit enforcement.