Ambient Radiation Levels Research Articles

Measurement and mapping of the electromagnetic radiation in the urban environment

ABSTRACTPeople are increasingly exposed to electromagnetic radiation with the rapid development of technologies such as broadcasting and mobile communication system. There is a concern that long-term exposure at low levels may be associated with various non-specific physical symptoms and ecological effects on animals and plants. It is extremely important to measure and analyze the electromagnetic radiation levels in order to protect people from the possible effects of electromagnetic radiation. A large-scale assessment of the effects of electromagnetic radiation on health or on ecology requires the ambient electromagnetic radiation levels over areas too vast to cover with conventional measurement methods. In this article, detailed information about the measurement tools and measurement method are given. The electromagnetic radiation exposure levels were measured on the main streets in the dense urban areas of Beijing, the capital of China. We apply ordinary kriging as an interpolation technique to assess the electromagnetic radiation exposure in large outdoor areas based on car-mounted measurements along the surrounding roads. The electromagnetic radiation exposure levels for larger areas can be investigated visually on the electromagnetic pollution map, which can assist decision makers by identifying the hotspots.

This Issue of ACTA

This Issue of ACTA

Ecological mechanisms can modify radiation effects in a key forest mammal of Chernobyl

AbstractNuclear accidents underpin the need to quantify the ecological mechanisms which determine injury to ecosystems from chronic low‐dose radiation. Here, we tested the hypothesis that ecological mechanisms interact with ionizing radiation to affect natural populations in unexpected ways. We used large‐scale replicated experiments and food manipulations in wild populations of the rodent, Myodes glareolus, inhabiting the region near the site of the Chernobyl disaster of 1986. We show linear decreases in breeding success with increasing ambient radiation levels with no evidence of any threshold below which effects are not seen. Food supplementation of experimental populations resulted in increased abundances but only in locations where radioactive contamination was low (i.e., below ≈ 1 μSv/h). In areas with higher contamination, food supplementation showed no detectable effects. These findings suggest that chronic low‐dose‐rate irradiation can decrease the stability of populations of key forest species, and these effects could potentially scale to broader community changes with concomitant consequences for the ecosystem functioning of forests impacted by nuclear accidents.

Radiation Monitoring of an Isolation Room for 131I Therapy After the Patients Were Released.

This study was performed to obtain a better understanding of the radiation environment in an I isolation room after the release of patients with metastasis from thyroid cancer that were treated with I doses ranging from 3.7 GBq (100 mCi) to 5.5 GBq (150 mCi) because there have not been any previous studies regarding the ambient radiation levels encountered in I isolation rooms after patients are released. Ambient radiation levels and total and removable surface contamination levels were monitored for 3 weeks after each patient's release (and before the entry of the next patient). An area located 0.75 m along the corridor outside the room, the door, window, bedside, and the wall of the shower room were monitored with a Nal scintillation survey meter, which was used to obtain readings of the ambient radiation level in six directions, and the mean value for each area was recorded. In addition, areas that were suspected to be highly contaminated, including the toilet bowl, toilet sink, bed head, back of the bed, sink, trash box, and the patient's pillow, were monitored for total surface contamination with a GM survey meter. Furthermore, the toilet's U-bend, toilet sink, bed guard, table, shielding, sink plug, and door knob were swabbed for monitoring removable surface contamination, which was measured using a well counter. Ambient radiation monitoring in an I isolation room showed that there was negligible risk of harm in terms of the occupational radiation dose level after patients were released. The ambient radiation dose rate was higher near the door because the sink and trash box were located nearby. The toilet bowl, the toilet's U-bend, and the area around the sink exhibited heavy surface contamination, so these areas require cautious hygiene management.

Spring and summer time ozone and solar ultraviolet radiation variations over Cape Point, South Africa

Abstract. The correlation between solar ultraviolet radiation (UV) and atmospheric ozone is well understood. Decreased stratospheric ozone levels which led to increased solar UV radiation levels at the surface have been recorded. These increased levels of solar UV radiation have potential negative impacts on public health. This study was done to determine whether the break-up of the Antarctic ozone hole has an impact on stratospheric columnar ozone (SCO) and resulting ambient solar UV-B radiation levels at Cape Point, South Africa, over 2007–2016. We investigated the correlations between UV index, calculated from ground-based solar UV-B radiation measurements and satellite-retrieved column ozone data. The strongest anti-correlation on clear-sky days was found at solar zenith angle 25∘ with exponential fit R2 values of 0.45 and 0.53 for total ozone column and SCO, respectively. An average radiation amplification factor of 0.59 across all SZAs was calculated for clear-sky days. The MIMOSA-CHIM model showed that the polar vortex had a limited effect on ozone levels. Tropical air masses more frequently affect the study site, and this requires further investigation.

Epidemiological variations and trends in health burden of glaucoma worldwide.

To evaluate the trends and variations in global health burden of glaucoma by year, age and sex, region and socio-economic status, using disability-adjusted life years (DALYs). The DALY numbers, crude DALY rate and age-standardized DALY rate globally and in each country were obtained the GBD 2015 study database. The corresponding human development index (HDI) and gross domestic product (GDP) per capita were obtained from the United Nations and World Bank. Environmental data were obtained from the WHO Global Health Observatory data repository. From 1990 to 2015, the DALY number and age-standardized DALY rate due to glaucoma increased by 122% and 15%, respectively. Both male and female showed similar increasing trend with ageing, with the peak at 60years old and increasing again since 75years old. Sex disparities in DALY number were noted, with higher burden among female than male in each age group (all p<0.001). The health burden of glaucoma was substantial unequal, with Gini coefficient of 0.865 for DALY number, 0.235 for crude DALY rate and 0.254 for age-standardized DALY rate, respectively. The age-standardized DALY was significantly associated with HDI, accounting for 22.2% variance across countries (R2 =0.222,p<0.001). Similarly, the GDP per capita was inversely associated with age-standardized DALY rate but can explain only 10.6% variations in age-standardized DALY rate (R2 =0.106,p<0.001). The age-standardized DALY rate due to glaucoma was positively associated with national levels of ultraviolet radiation and PM2.5 . The health burden of glaucoma continuously increased in the past 25years and distributed unequally. Lower socio-economic level, older age, female, higher ambient ultraviolet radiation and higher level of air pollution were significantly associated with higher burden of glaucoma.

Baseline Natural Radiation Level Survey of Iuleha Clan in Owan-West Local Government Area Edo State

Investigation of ambient radiation level of Iuleha clan in Owan – West Local Government Area, Edo State has been carried out using the radiation meter Digilert 50, Nuclear Radiation Monitor. The background natural radiation level Count per hour (Cph) of eighteen sites of the total expanse of the clan were measured. The Cph values ranged from 848μSv/hr (Aoma market) to 1308.00μSv/hr (Okagboro). It was discovered that sites with high Cph were close to granite deposit or had granite subsurface foundation.Keywords: Radiation level; Natural radioactivities; Ionizing radiation; Radiation pollution.

The geospatial relationship of pterygium and senile cataract with ambient solar ultraviolet in tropical Ecuador.

Tropical Ecuador presents a unique climate in which we study the relationship between the ambient levels of solar ultraviolet radiation and eye disease in the absence of a latitudinal gradient. The national distribution of surface ultraviolet, taking into account MODIS and OMI satellite observation of aerosol, ozone, surface albedo, local elevation and cloud fractions measured during 2011, was compared with the national pterygium (WHO ICD H11) and senile cataract (WHO ICD H25) incidence projected from the 2010 National Institute of Statistics and Census (Ecuador). Public Health Ministry projections for age categories 0 to 39, 40 to 59 and 60+ years were compared to surface ultraviolet irradiance data in 1040 parishes. Correlations drawn between modelled surface ultraviolet and eye disease incidence show a significant increase in both pterygium and senile cataract in the highest ambient exposure regions of the Pacific coast and western lowlands with incidence rates of 34.39 and 16.17 per 100 000 residents respectively. The lowest rates of incidence for pterygium (6.89 per 100 000) and senile cataract (2.90 per 100 000) were determined in high altitude sites and are attributed here to increased daily cloud fraction for parishes located in the Andean mountain range. The South American Andes experience the highest solar UV exposures on Earth and report frequent high incidence of keratinocyte cancer. Our results show the high Andes to be the location of the lowest eye disease incidence suggesting that both pterygium and senile cataract are the result of cumulative exposure to solar ultraviolet. These findings have clear implications for the agricultural workers and fishermen of the lowland districts of Ecuador, contrary to conventional understanding that greater risks are faced in locations of high altitude.

Reduced colonization by soil invertebrates to irradiated decomposing wood in Chernobyl

Soil is inhabited by a range of microbes, invertebrates and vertebrates that disintegrate and decompose dead wood and leaf litter. These communities can be perturbed by ionizing radiation from natural radiation sources or from radiation originating from nuclear accidents such as those at Chernobyl, Fukushima and Three Mile Island. We used experimental manipulations of wood quality due to differences in exposure to ionizing radiation among tree trunks and ambient radiation levels of the soil to test the hypothesis that radioactively contaminated wood would result in a negative correlation between the abundance of soil invertebrates colonizing slices of wood and level of radioactive contamination. We extracted soil invertebrates underneath decomposing wood using mustard powder diluted in water. The abundance of soil invertebrates extracted was highly repeatable at study sites and decreased with increasing ambient radiation and total dose measured with thermoluminescent dosimeters (TLDs). Four 10 cm thick slices of ca. 70-year old Scots pines (Pinus sylvestris) were deposited at 20 sites and the invertebrate taxa and their colonization and their abundance was assessed annually during 2014–2017. There were more soil invertebrates under uncontaminated than contaminated slices of wood. In addition, there were more soil invertebrates in areas with less ambient radioactivity, and there was an interaction effect between contamination of wood and ambient radiation implying that the role of contamination differed among slices. Finally, there was an increase in the abundance of soil invertebrates under wood slices during 2013–2017 implying that the abundance of soil invertebrates increased over time. These findings imply that the abundance of soil animals colonizing wood slices was dependent on background radiation, radioactive contamination of wood and the interaction between contamination of wood and ambient radiation.

Laser size reduction of radioactively contaminated structures

Due to the environment, nuclear decommissioning is an extremely challenging activity. High ambient radiation levels often preclude entry to the areas involved, and as the industry tries to minimize dose uptake, moderate radiation levels are now requiring remote solutions. In situ size reduction of process plant including vessels, containers, dissolvers, and pipework allows the removal of the nuclear inventory from a building prior to further decontamination and demolition. Ex situ size reduction comprises a dedicated facility to take in the existing nuclear waste inventory for further size reduction activity to achieve high waste management efficiencies. Traditional size reduction or cutting methods such as reciprocating saws or grinders pose a significant challenge for remote deployment platforms, where haptic feedback is lost and, when deployed, take considerable time to perform the task. Although remote engineered solutions for these tools are possible, they are complicated, unreliable, and expensive. Laser cutting is widely used in non-nuclear industrial sectors, and offers a more flexible and simpler method for size reduction. This paper presents results of two projects involving in situ and ex situ deployments of high power fiber-delivered lasers on two separate nuclear sites for size reduction of radioactively contaminated structures.

Radiation Safety: Management and Programs. HDomenech. Switzerland: Springer International Publishing, 2017. Hardcover 332. pp. Price: $141.49. ISBN 978‐3‐319‐42669‐3.

While most books have written about radiation safety concerning technical aspects, whether it be radiation biology, instrumentation, or radiation shielding, this book addresses the pragmatic question: What elements must be put in place to have a successful radiation safety program? The author intends that the book to be used as a practical guide for a radiation safety program for a wide variety of professionals. While the book provides very useful material, including many references from the International Atomic Energy Agency (IAEA) and the International Commission on Radiological Protection (ICRP), it is hurt by the author's attempt to cover too broad range of applications and the topics pertinent to those applications. The book is mostly suited for a physicist or engineer who has never setup a radiation safety program. In that context, the book could provide an outline of what items that must become part of the program. The book begins with a brief overview of the importance of physics in radiation safety. It then goes into the framework in which radiation is regulated, followed by chapters describing the specific elements needed for a radiation safety program. The highlight of the book is the chapter on “General Principles of Radiation Protection.” It includes very good discussions about the ICRP recommendations for employing justification and optimization to evaluate the uses of ionizing radiation. The discussion also provides a very useful set of tools that one can use in doing this assessment. Yet, the guidance provided on many other topics is not particularly helpful. For example, the discussion on individual monitoring of the worker doses gives no information beyond what is already found in the regulations. While the book notes that the worker dose at times must be assessed from the monitoring of ambient radiation levels, it conflates the assessment of dose for workers requiring monitoring with an evaluation to demonstrate no need to monitor: two different evaluations. In the discussion about control of radiation dose to the public, one finds information on the dispersion of radioactive material from satellites reentering the atmosphere and a short discussion on dose from the Chernobyl and Fukushima Daiichi nuclear power plant accidents. However, there is nothing about much more common means of limiting this dose such as control of radioactive effluents or shielding of accelerators. Similar examples of discussions that either omit important considerations or provide misleading guidance appear throughout the book. The book attempts to work within the framework of laws and regulations governed by the United States. However, the author, who has many years of experience as a government regulator for another country, appears to not be fully familiar with these requirements. The following three examples serve to illustrate this weakness. At one point the book states that the occupational dose limit for certain minors is 6 mSv, which is higher than the regulatory limit in the United States. In the discussion about the classification of an area, it muddles the distinction in NRC regulations between restricted areas and controlled areas and imposes many unnecessary requirements no matter which type of area one is discussing. The discussion of licensing in the United States does not show an understanding of the process. Still, the book provides good information on the general structure of a radiation safety program. At the end of Chapter 17, there is a 10-page Radiation Protection Program Development Checklist that one could use in developing a checklist specific to their own facility. The strength of this book is that it conveys the breadth of issues that must be addresses by a radiation safety program. Since the author tried to cover all these issues, very few practical guidelines are given. While a person with a good background in physics could use this book as a general guide to a radiation safety program, it is questionable whether that person would need the book or whether it would be better to go directly to the guidance already available from IAEA, ICRP, and the national regulatory agencies. Keith Brown is an Associate Director, Radiation Safety at University of Pennsylvania (Penn). He oversees the radiation protection and safety program at Penn and he is involved in many training and teaching programs of the university.

Assessment of the possibility of unglazed transpired type solar collector to be used for drying purposes: a comparative assessment of efficiency of unglazed transpired type solar collector with glazed type solar collector

Energy, which has become a key issue in global scale, has already posed a threat for the existence and development of mankind. Due to environmental degradation associated with energy consumption in all sectors, it is required to focus on utilization of sustainable energy sources. Solar energy, which is an environment friendly and sustainable energy source, is a promising alternative for fossil fuels. Drying processes in industrial sector accounts for about 12 to 20% of the total energy consumption. In developing countries, solar drying is utilized as a decentralized thermal application for the food preservation. Though natural sun-drying does not involve any cost, there are many disadvantages such as long drying time, contamination and intrusion of insects and rodents, which will result in low quality dried material. Currently, unglazed transpired type solar collectors are commonly used for building heating purposes but rarely for agricultural purposes. To check the possibility of unglazed transpired type solar collectors to be used for drying purposes, this study was conducted to compare the efficiency and performance of unglazed transpired type solar collector with conventional glazed type solar collector in local conditions. Dimensions of both solar collectors were designed as 1m x 1m in size. 5mm thick transparent glass sheet and perforated black painted metal sheet were used for solar radiation transmission in glazed type solar collector and unglazed transpired type solar collector respectively. Inlet and outlet temperature of both types of solar collectors, solar radiation, ambient temperature, wind speed and surrounding relative humidity were monitored. When compare the two types of solar collectors, there were no significant difference of solar collector’s temperature at their outlets with various levels of ambient temperature (28-32 °C), solar radiation (95.21-504.28 W/m2) and wind speed (0.43-1.05 m/s). The efficiency of unglazed transpired type solar collector was observed as 38.41 % under 0.0077 m3/s airflow rate, with average solar radiation of 304.24 W/m2. During lower solar radiation levels, comparatively higher collector’s efficiency was observed in unglazed transpired type solar collector than in glazed type solar collector. In addition, unglazed transpired type solar collector is a low cost and robust heating system. Hence, there is a potential to utilize unglazed transpired type solar collector as a substitute for glazed type solar collector for agricultural drying processes.

Measurement of ambient gamma radiation levels and radon concentration in drinking water of Koppa and Narasimharajapura taluks of Chikmagalur district, Karnataka, India

This study presents the results of indoor and outdoor ambient gamma dose rates and radon concentration in groundwater at different locations of Koppa and Narasimharajapura taluks of Chikmagalur district, (13°40' north latitude and 75° 62' east longitudes). The total annual effective dose ranged between 0.67 mSv/y and 1.76 mSv/y with an average value of 1.16 mSv/y. The calculated total annual effective dose was found to be higher than the world average. The radon concentration in groundwater was analyzed using radon emanometry technique. The measured radon concentrations ranged from 3.96 Bq/l to 90.63 Bq/l with an average value of 35.34 Bq/l. This study reveals that 80% of drinking water samples have radon levels higher than the maximum contaminant level of 11 Bq/l recommended by the United States Environmental Protection Agency. All the recorded radon concentration values were found to be well below the action level of 100 Bq/l recommended by the World Health Organization. It is also found that the dose due to borewell water samples is higher compared to dose due to water from other sources such as hand pump, open well, and tap water.

Temperature and UV light affect the activity of marine cell-free enzymes

Abstract. Microbial extracellular enzymatic activity (EEA) is the rate-limiting step in the degradation of organic matter in the oceans. These extracellular enzymes exist in two forms: cell-bound, which are attached to the microbial cell wall, and cell-free, which are completely free of the cell. Contrary to previous understanding, cell-free extracellular enzymes make up a substantial proportion of the total marine EEA. Little is known about these abundant cell-free enzymes, including what factors control their activity once they are away from their sites (cells). Experiments were run to assess how cell-free enzymes (excluding microbes) respond to ultraviolet radiation (UVR) and temperature manipulations, previously suggested as potential control factors for these enzymes. The experiments were done with New Zealand coastal waters and the enzymes studied were alkaline phosphatase (APase), β-glucosidase, (BGase), and leucine aminopeptidase (LAPase). Environmentally relevant UVR (i.e. in situ UVR levels measured at our site) reduced cell-free enzyme activities by up to 87 % when compared to controls, likely a consequence of photodegradation. This effect of UVR on cell-free enzymes differed depending on the UVR fraction. Ambient levels of UV radiation were shown to reduce the activity of cell-free enzymes for the first time. Elevated temperatures (15 °C) increased the activity of cell-free enzymes by up to 53 % when compared to controls (10 °C), likely by enhancing the catalytic activity of the enzymes. Our results suggest the importance of both UVR and temperature as control mechanisms for cell-free enzymes. Given the projected warming ocean environment and the variable UVR light regime, it is possible that there could be major changes in the cell-free EEA and in the enzymes contribution to organic matter remineralization in the future.

Going Back: Radiation and Intentions to Return amongst Households Evacuated after the Great Tohoku Earthquake

Based on a survey conducted with evacuees from the Fukushima radiation-affected region of Japan we examine intentions to return, eventually to the family homes. Many respondents do not intend to return, particularly those from tsunami-affected towns, but higher income households and those who evacuated to the same town are more likely to go back. Intentions are only weakly responsive to changes in ambient radiation levels and families with children are particularly unwilling to return to radiation affected areas, suggesting that the ongoing policy of active decontamination may have only a limited impact on eventual resettlement.

Effect of increased UV-B radiation on carotenoid accumulation and total antioxidant capacity in tobacco (Nicotiana tabacum L.) leaves.

Carotenoids are important components of plant antioxidant systems, which protect photosystems from photooxidative destruction during ultraviolet-B (UV-B) exposure. The influence of carotenoids on total antioxidant capacity (TAC) of plants has rarely been studied. In this study, tobacco (Nicotiana tabacum L., 'K326') seedlings exposed to UV-B radiation were used in order to evaluate the effects of ambient levels of UV-B radiation on carotenoid accumulation. The aim was to investigate whether carotenoids could enhance TAC as a means of UV protection. Our results showed that leaf carotenoid content in the low UV-B exposure (+9.75 μW/cm2) plants was approximately 8% higher than that observed in control plants at 2-8 days of exposure. At high UV-B exposure (+20.76 μW/cm2), the carotenoid content increased rapidly after 1 day's exposure (10.41% higher than the control), followed by a return to the content as in control plants. Furthermore, carotenoid content positively correlated with TAC (P = 0.024). These results suggest that carotenoids have antioxidant properties and play an important role in the antioxidant system. UV-B exposure increased the carotenoid synthesis capability of plants. The plants could deplete the carotenoids to scavenge excess ROS at high UV-B radiation levels, which protects the tobacco plant from oxidative damage caused by UV-B stress.

Optimization of exposure and countryside waste management for different accidental radioactive release

Since the Fukushima accident, Japanese scientists have been intensively monitoring ambient radiations in the highly contaminated territories situated within 80 km of the nuclear site. The surveys that were conducted through mainly carborne, airborne and in situ gamma-ray measurement devices, enabled to efficiently characterize the spatial distribution and temporal evolution of air dose rates induced by Caesium-134 and Caesium-137 in the terrestrial systems. These measurements revealed that radiation levels decreased at rates greater than expected from physical decay in 2011-2012 (up to a factor of 2), and dependent on the type of environment (i.e. urban, agricultural or forest). Unlike carborne measurements that may have been strongly influenced by the depuration of road surfaces, no obvious reason can be invoked for airborne measurements, especially above forests that are known to efficiently retain and recycle radiocaesium.The purpose of our research project is to develop a comprehensive understanding of the data acquired by Japanese, and identify the environmental mechanisms or factors that may explain such decays. The methodology relies on the use of a process-based and spatially-distributed dynamic model that predicts radiocaesium transfer and associated air dose rates inside/above a terrestrial environment (e.g., forests, croplands, meadows, bare soils and urban areas).Despite the lack of site-specific data, our numerical study predicts decrease rates that are globally consistent with both aerial and in situ observations. The simulation at a flying altitude of 200 m indicated that ambient radiation levels decreased over the first 12 months by about 45% over dense urban areas, 15% above evergreen coniferous forests and between 2 and 12% above agricultural lands, owing to environmental processes that are identified and discussed. In particular, we demonstrate that the decrease over evergreen coniferous regions might be due the combined effects of canopy depuration (through biological and physical mechanisms) and the shielding of gamma rays emitted from the forest floor by vegetation. Our study finally suggests that airborne surveys might have not reflected dose rates at ground level in forest systems, which were predicted to slightly increase by 5 to 10% during the same period of time.

Modelling the dynamics of ambient dose rates induced by radiocaesium in the Fukushima terrestrial environment

Since the Fukushima accident, Japanese scientists have been intensively monitoring ambient radiations in the highly contaminated territories situated within 80 km of the nuclear site. The surveys that were conducted through mainly carborne, airborne and in situ gamma-ray measurement devices, enabled to efficiently characterize the spatial distribution and temporal evolution of air dose rates induced by Caesium-134 and Caesium-137 in the terrestrial systems. These measurements revealed that radiation levels decreased at rates greater than expected from physical decay in 2011-2012 (up to a factor of 2), and dependent on the type of environment (i.e. urban, agricultural or forest). Unlike carborne measurements that may have been strongly influenced by the depuration of road surfaces, no obvious reason can be invoked for airborne measurements, especially above forests that are known to efficiently retain and recycle radiocaesium.The purpose of our research project is to develop a comprehensive understanding of the data acquired by Japanese, and identify the environmental mechanisms or factors that may explain such decays. The methodology relies on the use of a process-based and spatially-distributed dynamic model that predicts radiocaesium transfer and associated air dose rates inside/above a terrestrial environment (e.g., forests, croplands, meadows, bare soils and urban areas).Despite the lack of site-specific data, our numerical study predicts decrease rates that are globally consistent with both aerial and in situ observations. The simulation at a flying altitude of 200 m indicated that ambient radiation levels decreased over the first 12 months by about 45% over dense urban areas, 15% above evergreen coniferous forests and between 2 and 12% above agricultural lands, owing to environmental processes that are identified and discussed. In particular, we demonstrate that the decrease over evergreen coniferous regions might be due the combined effects of canopy depuration (through biological and physical mechanisms) and the shielding of gamma rays emitted from the forest floor by vegetation. Our study finally suggests that airborne surveys might have not reflected dose rates at ground level in forest systems, which were predicted to slightly increase by 5 to 10% during the same period of time.

Effects of radionuclide contamination on leaf litter decomposition in the Chernobyl exclusion zone

The effects of radioactive contamination on ecosystem processes such as litter decomposition remain largely unknown. Because radionuclides accumulated in soil and plant biomass can be harmful for organisms, the functioning of ecosystems may be altered by radioactive contamination. Here, we tested the hypothesis that decomposition is impaired by increasing levels of radioactivity in the environment by exposing uncontaminated leaf litter from silver birch and black alder at (i) eleven distant forest sites differing in ambient radiation levels (0.22–15μGyh−1) and (ii) along a short distance gradient of radioactive contamination (1.2–29μGyh−1) within a single forest in the Chernobyl exclusion zone. In addition to measuring ambient external dose rates, we estimated the average total dose rates (ATDRs) absorbed by decomposers for an accurate estimate of dose-induced ecological consequences of radioactive pollution. Taking into account potential confounding factors (soil pH, moisture, texture, and organic carbon content), the results from the eleven distant forest sites, and from the single forest, showed increased litter mass loss with increasing ATDRs from 0.3 to 150μGyh−1. This unexpected result may be due to (i) overcompensation of decomposer organisms exposed to radionuclides leading to a higher decomposer abundance (hormetic effect), and/or (ii) from preferred feeding by decomposers on the uncontaminated leaf litter used for our experiment compared to locally produced, contaminated leaf litter. Our data indicate that radio-contamination of forest ecosystems over more than two decades does not necessarily have detrimental effects on organic matter decay. However, further studies are needed to unravel the underlying mechanisms of the results reported here, in order to draw firmer conclusions on how radio-contamination affects decomposition and associated ecosystem processes.

25-hydroxyvitamin D status of pregnant women is associated with the use of antenatal vitamin supplements and ambient ultraviolet radiation.

Previous research suggests prevalent vitamin D deficiency in pregnant women residing in South Australia and the Eastern Seaboard, however recent data from Perth, Western Australia (WA) is lacking. This cross-sectional study of n=209 pregnant women (36-40 weeks of gestation, 84% white Caucasian) reports on the vitamin D (25[OH]D) status of a contemporary population of pregnant women in Perth, WA, with a focus on the relative contributions of supplemental vitamin D and ambient ultraviolet (UV) radiation to 25(OH)D levels. Mean (SD) season-adjusted 25(OH)D levels were 77.7 (24.6) nmol/l. The prevalence of vitamin D deficiency (25[OH]D<50 nmol/l) was 13.9%. Ambient UV radiation levels in the 90 days preceding blood draw were significantly correlated with serum 25(OH)D levels (unstandardized coefficient 2.82; 95% CI 1.77, 3.86, P<0.001). Vitamin D supplementation expressed as dose per kg of body weight was also positively correlated with serum 25(OH)D levels (unstandardized coefficient 0.744; 95% CI 0.395, 1.092, P<0.001). In conclusion, this study finds that vitamin D deficiency in a predominantly white Caucasian cohort of pregnant women is less prevalent than has been reported in other studies, providing useful information relating to supplementation and screening in this, and similar, populations.