Graphite foils as potential skin and epithelium dosimeters at therapeutic photon energies.

This work builds upon a prior study, examining the dosimetric utility of pencil lead and thin graphitic sheets, focusing upon the measurement of skin doses within the mammographic regime. In recognizing the near soft-tissue equivalence of graphite and the earlier-observed favourable thermoluminescence yield of thin sheets of graphite, this has led to present study of 50 µm thick graphite for parameters typical of external beam fractionated radiotherapy and skin dose evaluations. The graphite layers were annealed and then stacked to form an assembly of 0.5 mm nominal thickness. Using a 6 MV photon beam and delivering doses from 2- to 60 Gy, irradiations were conducted, the assembly first forming a superficial layer to a solid water phantom and subsequently underlying a 1.5 cm bolus, seeking to circumvent the build-up to electronic equilibrium for skin treatments. Investigations were made of several dosimetric properties arising from the thermoluminescence yield of the 50 µm thick graphite slabs, in particular proportionality and sensitivity to dose. The results show excellent sensitivity within the dose range of interest, the thermoluminescence response varying with increasing depth through the stacked graphite layers, obtaining a coefficient of determination of 90%. Acknowledging there to be considerable challenge in accurately matching skin thickness with dose, the graphite sheets have nevertheless shown considerable promise as dosimeters of skin, sensitive in determination of dose from the surface of the graphite through to sub-dermal depth thicknesses.

Carbon rich media for luminescence-based surface dosimetry and study of associated surface defects.

The present study continues research into the utilisation of carbonaceous media for medical radiation dosimetry, focusing on the effects of surface area-to-volume ratio and carbon content on structural interaction alterations and dosimetric properties in sheet- and bead-type graphitic materials (with the respective carbon content of ∼98 wt% and ∼90 wt%). Using 60Co gamma-rays and doses from 0.5 Gy to 20 Gy, the study has been made of the response of commercially available graphite in the form of 0.1 mm, 0.2 mm, 0.3 mm and 0.5 mm thick sheets, also of activated carbon beads. Confocal Raman and photoluminescence spectroscopy have been employed, examining radiation-induced structural interaction alterations. Dose-dependent variation in the Raman intensity ratio ID/IG relates to the varying dominance of defect generation and dose-driven defect annealing. Of the various thickness graphite sheets, the 0.1 mm thick medium possesses the greatest surface area-to-volume ratio. Perhaps unsurprisingly, it also exhibits the greatest thermoluminescence (TL) yield compared to that of the other carbonaceous sheet foils used herein. Moreover, the second greatest mass-normalised TL yield has been observed to be that of the porous beads, reflected in the greater defect density (ID/IG > 2) when compared to the other media, due in part to their inherent feature of large internal surface area. Considering the challenge posed in matching skin thickness with skin dose, the near tissue equivalent graphite sheets show particular promise as a skin dosimeter, sensitive as a function of depth.

Dosimetric characteristics of Gd-doped silica glass subjected to neutron and gamma irradiations.

The dosimetric characteristics of newly developed gadolinium (Gd) glass dosimeter produced via sol-gel method are reported. Irradiation were made using a 750 kW neutron flux thermal power and 1.25 MeV 60Co gamma rays with entrance doses from 2 to 10 Gy. Investigation has been done on various Gd dopant concentrations, ranging from 1 to 10 mol%. The Gd-doped silica glass have been characterised for thermoluminescence (TL) dose response, sensitivity, linearity index, glow curve and kinetic parameter analysis. For particular dopant concentration obtained in 6 mol% Gd, the least squares fit shows the change in TL yield, correlation coefficient (r2) of better than 0.980 (at 95% confidence level), with neutron and gamma exposure to be 8 and 4 times greater than that of 1 mol% Gd, respectively. Broad peaks in the absence of any sharp peak observed in the glow curve confirms the amorphous nature of the prepared glass. A glow curve of Gd-doped SiO2 sample is observed with a single prominent peak (Tm) within 200-250 °C (peak shifting appears with respect to the increment of dopant concentration) and 350 °C (for all respective Gd dopants) for neutron and gamma irradiations, respectively. Deconvolution shows the glow curves of the Gd-doped SiO2 glass to be formed of seven and five overlapping peaks, with figures of merit below 2% (FOM) of between 1.38-1.79 and 1.30-1.97 for the particular neutron and gamma irradiations, respectively. Through use of Glowfit deconvolution software, the key trapping parameters of activation energy, E and frequency factor, s-1 were calculated for the Gd-doped SiO2 glass. The mechanism of TL yield with the gradual increase in Gd concentrations and doses is explained upon the incorporation of Gd and radiation damage that change the structure of the electron traps in the glass matrix. These early results indicate that selectively screened Gd-SiO2 glass can be developed into a promising TL system towards dosimetric applications.

The Usages and Potential Uses of Alginate for Healthcare Applications.

Due to their unique properties, alginate-based biomaterials have been extensively used to treat different diseases, and in the regeneration of diverse organs. A lot of research has been done by the different scientific community to develop biofilms for fulfilling the need for sustainable human health. The aim of this review is to hit upon a hydrogel enhancing the scope of utilization in biomedical applications. The presence of active sites in alginate hydrogels can be manipulated for managing various non-communicable diseases by encapsulating, with the bioactive component as a potential site for chemicals in developing drugs, or for delivering macromolecule nutrients. Gels are accepted for cell implantation in tissue regeneration, as they can transfer cells to the intended site. Thus, this review will accelerate advanced research avenues in tissue engineering and the potential of alginate biofilms in the healthcare sector.

Correction: Tailored Ge-doped fibres for passive electron radiotherapy dosimetry.

[This corrects the article DOI: 10.1371/journal.pone.0235053.].

EVALUATION OF ANNUAL RADIATION EXPOSURE OF STAFF IN A CARDIAC CATHETERIZATION DEPARTMENT IN SAUDI ARABIA.

The objective of this study is to estimate the annual effective dose for cardiologists and nurses by measuring Hp(10) and Hp(0.07) during cardiac catheterization procedures. A total of 16 staffs members were working in interventional cardiology during 1 year at a tertiary hospital. The occupational dose was measured using calibrated thermo-luminescent dosemeters (TLD-100, LiF:Mg,Ti). The overall mean and range of the annual Hp(10) and Hp(0.07) (mSv) for cardiologists were 3.7 (0.13-14.5) and 3.2 (0.21-14.7), respectively. Cardiologists were frequently exposed to higher doses compared with nurses and technologists. The exposure showed wide variations, which depend on occupation and workload. Staff is adhered to radiation protection guidelines regarding shielding the trunk, thyroid shield, thus appropriately protected. Lens dose measurement is recommended to ensure that dose limit is not exceeded.

Electrocatalytic and structural properties and computational calculation of PAN-EC-PC-TPAI-I2 gel polymer electrolytes for dye sensitized solar cell application.

In this study, gel polymer electrolytes (GPEs) were prepared using polyacrylonitrile (PAN) polymer, ethylene carbonate (EC), propylene carbonate (PC) plasticizers and different compositions of tetrapropylammonium iodide (TPAI) salt. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) measurements were done using non-blocking Pt-electrode symmetric cells. The limiting current (J lim), apparent diffusion coefficient of triiodide ions and exchange current were found to be 12.76 mA cm-2, 23.41 × 10-7 cm2 s-1 and 11.22-14.24 mA cm-2, respectively, for the GPE containing 30% TPAI. These values are the highest among the GPEs with different TPAI contents. To determine the ionic conductivity, the EIS technique was employed with blocking electrodes. The GPE containing 30% TPAI exhibited the lowest bulk impedance, R b (22 Ω), highest ionic conductivity (3.62 × 10-3 S cm-1) and lowest activation energy. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques were utilized for structural characterization. Functional group interactions among PAN, EC, PC and TPAI were studied in the FTIR spectra of the GPEs. An up-shift of the XRD peak indicates the polymer-salt interaction and possible complexation of the cation (TPA+ ion) with the lone pair of electrons containing site -C[triple bond, length as m-dash]N at the N atom in the host polymer matrix. On the other hand, computational study shows that TPAI-PAN based GPE possesses the lowest frontier orbital bandgap, which coincided with the enhanced electrochemical and electrocatalytic performance of GPE. The dye-sensitized solar cell (DSSC) fabricated with these GPEs showed that the J SC (19.75 mA cm-2) and V OC (553.8 mV) were the highest among the GPEs and hence the highest efficiency, η (4.76%), was obtained for the same electrolytes.

Tailored Ge-doped fibres for passive electron radiotherapy dosimetry.

Study has been made of the thermoluminescence yield of various novel tailor-made silica fibres, 6 and 8 mol % Ge-doped, with four differing outer dimensions, comprised of flat and cylindrical shapes, subjected to electron irradiation. Main thermoluminescence dosimetric characteristics have been investigated, including the glow curve, dose response, energy dependence, minimum detectable dose, effective atomic number, linearity of index and sensitivity of the fibres. The studies have also established the uncertainties involved as well as the stability of response in terms of fading effect, reproducibility and annealing. In addition, dose-rate dependence was accounted for as this has the potential to be a significant factor in radiotherapy applications. The 6 and 8 mol % fibres have been found to provide highly linear dose response within the range 1 to 4 Gy, the smallest size flat fibre, 6 mol% Ge-doped, showing the greatest response by a factor of 1.1 with respect to the highly popular LiF phosphor-based medium TLD100. All of the fibres also showed excellent reproducibility with a standard deviation of < 2% and < 4% for 6 and 8 mol % Ge-doped fibres respectively. For fading evaluation, the smallest 6 mol% Ge-doped dimension flat fibre, i.e., 85 × 270 µm displayed the lowest signal loss within 120 days post-irradiation, at around 26.9% also showing a response superior to that of all of the other fibres. Moreover, all the fibres and TLD-100 chips showed independence with respect to electron irradiation energy and dose-rate. Compared with the 8 mol% Ge-doped optical fibres, the 6 mol% Ge-doped flat optical fibres have been demonstrated to possess more desirable performance features for passive dosimetry, serving as a suitable alternative to TLD-100 for medical irradiation treatment applications.

Natural dead sea salt and retrospective dosimetry.

Accidents resulting in widespread dispersal of radioactive materials have given rise to a need for materials that are convenient in allowing individual dose assessment. The present study examines natural Dead Sea salt adopted as a model thermoluminescence dosimetry system. Samples were prepared in two different forms, loose-raw and loose-ground, subsequently exposed to 60Co gamma-rays, delivering doses in the range 2-10 Gy. Key thermoluminescence (TL) properties were examined, including glow curves, dose response, sensitivity, reproducibility and fading. Glow curves shapes were found to be independent of given dose, prominent TL peaks for the raw and ground samples appearing in the temperature ranges 361-385 ºC and 366-401 ºC, respectively. The deconvolution of glow curves has been undertaken using GlowFit, resulting in ten overlapping first-order kinetic glow peaks. For both sample forms, the integrated TL yield displays linearity of response with dose, the loose-raw salt showing some 2.5 × the sensitivity of the ground salt. The samples showed similar degrees of fading, with respective residual signals 28 days post-irradiation of 66% and 62% for the ground and raw forms respectively; conversely, confronted by light-induced fading the respective signal losses were 62% and 80%. The effective atomic number of the Dead Sea salt of 16.3 is comparable to that of TLD-200 (Zeff 16.3), suitable as an environmental radiation monitor in accident situations but requiring careful calibration in the reconstruction of soft tissue dose (soft tissue Zeff 7.2). Sample luminescence studies were carried out via Raman and Photoluminescence spectroscopy as well as X-ray diffraction, ionizing radiation dependent variation in lattice structure being found to influence TL response.

Thermoluminescence response of X-ray irradiated commercial chalk.

Present research concerns the TL signal stored in chalk of the variety commercially available for writing on blackboards. Samples of this have been subjected to x-ray irradiation, the key dosimetric parameters investigated including dose and energy response, sensitivity, fading and glow curve analysis. Three types of chalk have been investigated, each in five different colours. The samples were annealed at 323 K prior to irradiation. For all three chalk types and all five colours, the dose response has been found linear over the investigated dose range, 0-9 Gy. Regardless of type or colour, photoelectric energy dependency is apparent at the low energy end down to the lowest investigated accelerating potential of 30 kV. Crayola (Yellow) has shown the greatest TL sensitivity, thus selection has been made to limit further analysis to this medium alone, specifically in respect of glow curve and fading study. In addition, elemental compositional and structural change characterizations were made for the same medium, utilizing Energy Dispersive X-Ray (EDX) and Raman spectroscopy, respectively.

ASSESSMENT OF NATURAL RADIOACTIVITY IN MAIZE AND ESTIMATION OF CONCOMITANT DOSE TO NIGERIAN VIA INGESTION PATHWAY.

Uranium, thorium and potassium are the most abundant naturally occurring radioactive materials (NORMs) found in soils and other environmental media including foodstuffs. Since the human exposures to NORMs is an unavoidable phenomenon, in such a way that they can easily find their way to human being via food chain, detailed knowledge on their presence in foodstuffs is necessary to assess the radiation dose to the population. Thus, the present study concerns the assessment of natural radioactivity in maize, a staple foodstuff for Nigerian, via HPGe gamma-ray spectrometry. Activity concentrations (Bq/kg) in the maize samples were found to be in the range of 6.1 ± 0.6-8.2 ± 1.3, 2.2 ± 0.4-5.1 ± 0.7 and 288 ± 16-401 ± 24 for 226Ra, 232Th and 40K, respectively. Measured data for 226Ra and 232Th show below the world average values of 67 Bq/kg and 82 Bq/kg, respectively, while the activity of 40K exceeds the global average of 310 Bq/kg. The annual effective dose via the maize consumption was found to be far below the UNSCEAR recommended ingestion dose limit of 290 µSv/y, and the estimated lifetime cancer risk show lower than the ICRP (1991) cancer risk factor of 2.5 × 10-3 based on the additional annual dose limit of 1 mSv for general public, thus pose no adverse health risk to the Nigerian populace.

EVALUATION OF RADON CONCENTRATION IN IRRIGATION AND DRINKING WATERS FROM THE EASTERN PART OF OMAN AND ESTIMATION OF EFFECTIVE DOSES TO OMANIS.

The present study concerns measurement of the radon concentration in drinking and irrigation waters obtained from the eastern part of Oman, in particular in regard to water quality assessment of the region. The samples were collected from different places covering most types of water sources in the region. A passive and time-integrated track etch detector (LR-115 type II) combined with a high-resolution optical microscope has been used to obtain the radon concentration in the studied samples. Values of dissolved radon in water varied among the water sources; the highest concentration of radon was found to be 363 Bq m-3 in a drinking water sample while well water used for irrigation showed the lowest value, at 140 Bq m-3. Measured data for all water sources are below the permissible limit of 11.1 kBq m-3 recommended by the US-EPA. Annual effective doses for the studied samples were in the range 0.38-0.99 µSv y-1 which is significantly less than the action level recommended by the WHO (0.1 mSv y-1), indicating that the water sources in the Jalan BBH region of Oman are safe to use. The obtained data may serve as a reference for any future radiological study of the waterbody of this region.

Evaluation of Ge-doped silica fibre TLDs for in vivo dosimetry during intraoperative radiotherapy.

Ge-doped silica fibre (GDSF) thermoluminescence dosimeters (TLD) are non-hygroscopic spatially high-resolution radiation sensors with demonstrated potential for radiotherapy dosimetry applications. The INTRABEAM® system with spherical applicators, one of a number of recent electronic brachytherapy sources designed for intraoperative radiotherapy (IORT), presents a representative challenging dosimetry situation, with a low keV photon beam and a desired rapid dose-rate fall-off close-up to the applicator surface. In this study, using the INTRABEAM® system, investigations were made into the potential application of GDSF TLDs for in vivo IORT dosimetry. The GDSFs were calibrated over the respective dose- and depth-range 1 to 20 Gy and 3 to 45 mm from the x-ray probe. The effect of different sizes of spherical applicator on TL response of the fibres was also investigated. The results show the GDSF TLDs to be applicable for IORT dose assessment, with the important incorporated correction for beam quality effects using different spherical applicator sizes. The total uncertainty in use of this type of GDSF for dosimetry has been found to range between 9.5% to 12.4%. Subsequent in vivo measurement of skin dose for three breast patients undergoing IORT were performed, the measured doses being below the tolerance level for acute radiation toxicity.

Raman spectroscopy and X-ray photo-spectroscopy analysis of graphite media irradiated at low doses.

We explore the utility of controlled low-doses (0.2-100 Gy) of photon irradiation as initiators of structural alteration in carbon-rich materials. To-date our work on carbon has focused on ß-, x- and γ-irradiations and the monitoring of radiotherapeutic doses (from a few Gy up to some tens of Gy) on the basis of the thermoluminescence (TL) signal, also via Raman and X-ray photo-spectroscopy (XPS), providing analysis of the dose dependence of single-walled carbon nanotubes (SWCNT). The work has been extended herein to investigate possibilities for analysis of structural alterations in graphite-rich mixtures, use being made of two grades of graphite-rich pencil lead, 8H and 2B, both being in the form produced for mechanical pencils (propelling or clutch pencils). 2B has the greater graphite content (approaching 98 wt %), 8H being a mixture of C, O, Al and Si (with respective weight percentages 39.2, 38.2, 9.8 and 12.8). Working on media pre-annealed at 400 °C, both have subsequently been irradiated to penetrating photon-mediated doses. Raman spectroscopy analysis has been carried out using a 532 nm laser Raman spectrometer, while for samples irradiated to doses from 1 to 40 Gy, XPS spectra were acquired using Al Kα sources (hv ∼1400 eV); carbon KLL Auger peaks were acquired using 50 eV Pass Energy. At these relatively low doses, alterations in order-disorder are clearly observed, defect generation and internal annealing competing as dominating effects across the dose range.

Monte Carlo skin dose simulation in intraoperative radiotherapy of breast cancer using spherical applicators.

The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators. HIGHLIGHTS: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin safety.

Environmental monitoring through use of silica-based TLD.

The sensitivity of a novel silica-based fibre-form thermoluminescence dosimeter was tested off-site of a rare-earths processing plant, investigating the potential for obtaining baseline measurements of naturally occurring radioactive materials. The dosimeter, a Ge-doped collapsed photonic crystal fibre (PCFc) co-doped with B, was calibrated against commercially available thermoluminescent dosimetry (TLD) (TLD-200 and TLD-100) using a bremsstrahlung (tube-based) x-ray source. Eight sampling sites within 1 to 20 km of the perimeter of the rare-earth facility were identified, the TLDs (silica- as well as TLD-200 and TLD-100) in each case being buried within the soil at fixed depth, allowing measurements to be obtained, in this case for protracted periods of exposure of between two to eight months. The values of the dose were then compared against values projected on the basis of radioactivity measurements of the associated soils, obtained via high-purity germanium gamma-ray spectrometry. Accord was found in relative terms between the TL evaluations at each site and the associated spectroscopic results. Thus said, in absolute terms, the TL evaluated doses were typically less than those derived from gamma-ray spectroscopy, by ∼50% in the case of PCFc-Ge. Gamma spectrometry analysis typically provided an upper limit to the projected dose, and the Marinelli beaker contents were formed from sieving to provide a homogenous well-packed medium. However, with the radioactivity per unit mass typically greater for smaller particles, with preferential adsorption on the surface and the surface area per unit volume increasing with decrease in radius, this made for an elevated dose estimate. Prevailing concentrations of key naturally occurring radionuclides in soil, 226Ra, 232Th and 40K, were also determined, together with radiological dose evaluation. To date, the area under investigation, although including a rare-earth processing facility, gives no cause for concern from radiological impact. The current study reveals the suitability of the optical fibre based micro-dosimeter for all-weather monitoring of low-level environmental radioactivity.

Thermoluminescence Response of Ge-Doped Cylindrical-, Flat- and Photonic Crystal Silica-Fibres to Electron and Photon Radiation.

Study has been made of the thermoluminescence (TL) response of silica-based Ge-doped cylindrical, flat and photonic crystal fibres (referred to herein as PCF-collapsed) to electron (6, 12 and 20 MeV) and photon (6, 10 MV) irradiation and 1.25 MeV γ-rays, for doses from 0.1 Gy to 100 Gy. The electron and photon irradiations were delivered through use of a Varian Model 2100C linear accelerator located at the University of Malaya Medical Centre and γ-rays delivered from a 60Co irradiator located at the Secondary Standard Dosimetry Laboratory (SSDL), Malaysian Nuclear Agency. Tailor-made to be of various dimensions and dopant concentrations (6-10% Ge), the fibres were observed to provide TL yield linear with radiation dose, reproducibility being within 1-5%, with insensitivity to energy and angular variation. The sensitivity dependency of both detectors with respect to field size follows the dependency of the output factors. For flat fibres exposed to 6 MV X-rays, the 6% Ge-doped fibre provided the greatest TL yield while PCF-collapsed showed a response 2.4 times greater than that of the 6% Ge-doped flat fibres. The response of cylindrical fibres increased with core size. The fibres offer uniform response, high spatial resolution and sensitivity, providing the basis of promising TL systems for radiotherapy applications.

Assessment of Radiation and Heavy Metals Risk due to the Dietary Intake of Marine Fishes (Rastrelliger kanagurta) from the Straits of Malacca.

The environment of the Straits of Malacca receives pollution as a result of various industrial and anthropogenic sources, making systematic studies crucial in determining the prevailing water quality. Present study concerns concentrations of natural radionuclides and heavy metals in marine fish (Rastrelliger kanagurta) collected from the Straits of Malacca, since aquatic stock form an important source of the daily diet of the surrounding populace. Assessment was made of the concentrations of key indicator radionuclides (226Ra, 232Th, 40K) and heavy metals (As, Mn, Fe, Cr, Ni, Zn, Cu, Co, Sr, Al, Hg and Pb) together with various radiation indices linked to the consumption of seafish. The annual effective dose for all detected radionuclides for all study locations has been found to be within UNSCEAR acceptable limits as has the associated life-time cancer risk. The overall contamination of the sampled fish from heavy metals was also found to be within limits of tolerance.

Natural radioactivity and effective dose due to the bottom sea and estuaries marine animals in the coastal waters around Peninsular Malaysia.

Malaysia is among the countries with the highest fish consumption in the world and relies on seafood as a main source of animal protein. Thus, the radioactivity in the mostly consumed marine animals such as fishes, crustaceans and molluscs collected from the coastal waters around Peninsular Malaysia has been determined to monitor the level of human exposure by natural radiation via seafood consumption. The mean activity concentrations of naturally occurring radionuclides (226)Ra ((238)U), (228)Ra ((232)Th) and (40)K ranged from 0.67 ± 0.19 Bq kg(-1) (Perna viridis) to 1.20 ± 0.70 Bq kg(-1) (Rastrelliger), from 0.19 ± 0.17 Bq kg(-1) (Teuthida) to 0.82 ± 0.67 Bq kg(-1) (Caridea) and from 34 ± 13 Bq kg(-1) (Caridea) to 48 ± 24 Bq kg(-1) (Teuthida), respectively. The mean annual committed effective dose due to the individual radionuclides shows an order of (228)Ra > (226)Ra > (40)K in all marine samples. The obtained doses are less than the global internal dose of 290 µSv y(-1) set by the United Nations Scientific Committee on the Effects of Atomic Radiation, discarding any significant radiological risks to the populace of Peninsular Malaysia.