Maximum Permissible Levels Research Articles

Magnetic fields in the workplace during the operation of contact spot welding installations

Contact welding is one of the most common types of welding. According to the technological method of obtaining joints, contact welding can be spot, relief, butt, suture. Spot contact welding a high productivity. Specialists use spot welding more often than other types of welding. The formation of permanent joints of materials occurs as a result of electric heating and deformation during compression. Workers warm up the products with pulses of alternating, direct or unipolar current of industrial frequency 50 Hz. Researchers have registered adverse factors at the welder's workplace that have an impact on health. These are high temperature, splashes and metal vapors, pulsed magnetic fields (PMF) of industrial frequency 50 Hz. The study aims to explore the levels of pulsed magnetic fields of industrial frequency of 50 Hz at workplaces during the operation of contact spot welding installations. The study included the study of the technology of contact spot welding, instrumental measurements and hygienic assessment of the levels of PMF of the industrial frequency of 50 Hz at the welders' workplaces during the operation of equipment in normal mode. Specialists have performed instrumental measurements of PMF levels with a TP2-2U milliteslameter during operation of three models of semi-automatic welding machines based on spot welding installations. The researchers recalculated the measured levels of magnetic field induction to the maximum operating current (Imax) possible during the technological process. Instrumental measurements showed that the magnetic field strength at the welders' workplaces depended on the type of installation, the distance from the radiation source, the localization of exposure, and welding of specific products. Experts registered the highest levels of magnetic fields in the arm area from 1096.0 to 5512.0 A/m. At the maximum operating current, the magnetic field strength can reach 13 678.0-11 024.0 A/m. The study showed that the intensity of pulsed magnetic fields of industrial frequency 50 Hz in the workplace can exceed the maximum permissible levels. To protect workers, it is necessary to limit the time of exposure to magnetic fields. Limitations. The studies are preliminary in nature and have limitations on the scope of the study.

Use of natural sorbents for accelerated bioremediation of grey forest soil contaminated with crude oil

Due to the extensive oil extraction and transportation that occurs in oil-producing countries, many lands remain contaminated because of accidental leakages. Despite its low cost and environmentally safe nature, bioremediation technology is not always successful, mainly because of the soil toxicity to the degrading microbial populations and plants. Here we report a three-year microfield experiment on the influence of natural sorbents of mineral (zeolite, kaolinite, vermiculite, diatomite), organic (peat), carbonaceous (biochar) origin, and a mixed sorbent ACD (composed of granular activated carbon and diatomite) on the bioremediation of grey forest soil contaminated with weathered crude oil (40.1 g total petroleum hydrocarbons (TPH) kg−1). Optimal doses of the sorbents significantly accelerated bioremediation of petroleum-contaminated soil through bioaugmentation followed by phytoremediation. The main reason for the influence of the sorbent amendments relied upon the creation of optimal conditions for the activation of hydrocarbon-utilizing bacteria and plant growth due to the reduction of soil toxicity, as well as maintaining an optimal pH and water-air regime in the soil. That happened because of reducing the soil hydrophobicity, increasing porosity and water holding capacity. The content of the TPH in the best samples (2% biochar or ACD) reduced to their local permissible concentration accepted for remediated soils in the Russian Federation (≤5 g kg−1) after two warm seasons compared to that after three warm seasons in the other samples. Although some sorbents decelerated biodegradation of highly condensed polycyclic aromatic hydrocarbons (PAHs, including benzo(a)pyrene) in the soil, the overall risk from the residual contaminants present in the remediated soil and plants was minimized. The final total content of the main PAHs in the sorbent-amended soils did not exceed the maximal permissible levels that are accepted in most EU countries (1000–40,000 μg kg−1), and they did not accumulate in the aboveground phytomass of grasses in dangerous concentrations.

The Concept of Active Voice Reduction using Multipole Secondary Source: Case Study of C-150 Aircraft

In order to protect residents living around the airport from aircraft noise disturbance, regulations have been set for the maximum permissible noise level limit. One of the international regulations that regulate the limits of aircraft exterior noise levels is the Federal Aviation Regulation (FAR) part 36 of the United States Regulatory Agency, or the Civil Aviation Safety Regulation (CASR) part 36 of the national regulatory agency. In addition, for military purposes, observer planes are also needed with the lowest possible sound level such that they will not attract the enemy's attention. This paper contains the concept of active exterior sound control/elimination with an unconventional secondary source method (anti-noise), using the multipole secondary source method. Multipole secondary sources are developed based on Taylor series expansion to obtain higher order secondary sources, such as dipoles, quadrupoles, octopoles, and so on, which are used for noise canceling. A significant noise reduction can be obtained by using a high-order secondary source and by optimizing the power of the secondary source. Numerical simulation of noise reduction in the free field was carried out by this method. The simulation results show that noise reduction reaches 50 dB at 200 Hz. The method, which is still a concept, was then used to simulate noise reduction on a Cessna-150 aircraft.

PLL Based Method for Supraharmonics Emission Assessment

Supraharmonic (SH) disturbances are generated mainly by power electronics whose usage has increased significantly in the last decades. Consequently, supraharmonics have increased as well. The SH frequency range from 2 kHz to 150 kHz still lacks a normative measurement method. Compatibility levels and emission limits of SH are commonly presented as quasi-peak (QP) detector values for a bandwidth (BW) of 200 Hz measured by CISPR 16 receivers. In this context, this paper proposes an optimized method emulating the CISPR 16 receiver with QP detector for measuring grid disturbance levels. It makes innovative use of PLL (Phase-Locked Loop) units for estimating the highest distortion levels in the SH frequency range of the test signal, and in sequence, the QP detector with the appropriate specifications in the CISPR 16 standard is applied. Different cases of both synthetic and real signals were applied to the proposed method, which showed to be efficient in evaluating SH levels for current and voltage signals. An analysis of maximum permissible distortion levels is performed considering an individual SH distortion. In addition, the proposed method presents a computational cost reduction of approximately 91% in relation to the CISPR 16 method considering a specific case of signal containing SH distortions used for power quality analysis.

Polyaniline and polypyrrole impregnated polyethersulfone based composite polymer beads for defluoridation application

Various composite conductive polymeric beads were prepared by phase inversion method for defluoridation studies. Base polymer (polyether sulfone) was impregnated with doped and undoped polyaniline (dopant: para toluene sulfuric acid). However, highest fluoride uptake capacity of 40 mg/g was observed in case of polypyrrole (dopant: sodium lauryl sulphate) impregnated beads. Morphology of prepared beads revealed their porous characteristics. Apart from this, lauryl sulphate ions in doped polypyrrole chains played an important role in electrostatic adsorption of fluoride ions, as evident from spectral analysis. Optimum equilibrium conditions were obtained at an adsorbent dosage of 10 g/L. Uptake capacity of doped polypyrrole impregnated beads decreased with pH. Fluoride uptake by beads was endothermic and physical in nature. Adsorption kinetics followed pseudo-second order model. Negative effect was shown by carbonate and potassium ions while positive effect was shown by magnesium ions during uptake process. Regeneration was carried for six cycles and it showed a saturated uptake capacity for the last three cycles. Dynamic filtration studies were also carried out using these beads. It was observed that a microcolumn operated in gravity filtration mode can treat 0.05 and 0.03 times of its bed volume at maximum permissible levels of fluoride for distilled and tap water simulated feed solutions, respectively.

Working conditions, occupational morbidity, risks of violation health of drivers of mining machines in quarries

Introduction. Recent studies have shown that working conditions at mining enterprises remain harmful and dangerous. We characterize the working conditions by a set of factors of the production environment that affect the functional state of the body of workers and their working capacity. It depends on the equipment used, technologies, objects, products of labor. They are specific to each enterprise. In these conditions, the definition of occupational risks of violation of the health of miners becomes particularly relevant. The study aims to assess the current working conditions, the state of professional performance, to determine the risks of health disorders of the drivers of mining machines at ore quarries. Materials and methods. The researchers have conducted hygienic studies to assess production factors at ore quarries. We have presented an analysis of materials for a special assessment of working conditions at workplaces for ore quarries belonging to the Mining and Metallurgical Trade Union of Russia. Experts have summarized materials on occupational morbidity of employees over the past five years. The researchers have performed a cross-sectional epidemiological study to assess the risk of developing chronic general somatic diseases in mining machine drivers. Results. The article provides a hygienic assessment of working conditions in modern quarries, shows the complex impact on workers of the dust and gas factor, noise and vibration, microclimate. The authors present classes of working conditions for employees of the main professions, the results of a special assessment of working conditions. We have given an analysis of occupational morbidity in the quarries included in the GMPR and GOK “Lebedinsky” over the past five years. Researchers have found that diseases of the musculoskeletal system and connective tissue, as well as diseases of the circulatory system are production-related in workers engaged in open-pit mining. Conclusion. In the conditions of using high-performance mining equipment for open-pit mining of ores, a complex of production factors affects workers of leading professions. The authors give a general assessment of the working conditions at the workplaces of these professions: this is a harmful third class with varying degrees of harmfulness. The current set of production factors determines the level of occupational morbidity, which has been trending downward in recent years. The leading place belongs to vibration sickness, it is closely related to the increased values of the maximum permissible levels and the equivalent adjusted level of vibration velocity at the workplaces of drilling rig drivers, excavators and drivers of heavy-duty dump trucks. The high prevalence and risk of developing chronic diseases of the musculoskeletal system and connective tissue and diseases of the circulatory system, as well as a significant increase in indicators with an increase in work experience in harmful working conditions, allow us to speak about the production conditionality of these diseases in workers engaged in open-pit mining. Ethics. This study did not require the conclusion of the Ethics committee.

Design improvements in modern distribution transformers

In the paper design improvements of distribution transformers related to improved energy efficiency and environmental awareness are discussed. Eco design of transformers, amorphous transformers, voltage regulated transformers and transformers filled with ester liquids are analyzed. As a consequence of growing energy efficiency importance, European Commission has adopted new regulation which defines maximum permissible levels of load and no-load losses of transformers with rated power ≤ 3150 kVA, and minimum peak efficiency index for transformers with rated power > 3150 kVA up to 40 MVA. The impact of new regulation on the design and economy of transformer is presented. Amorphous transformers, with up to 70 % lower no-load losses in comparison to the conventional transformers, could be an alternative with respect to energy efficiency. Although their initial price is higher than the price of conventional transformers, some studies show that they might have economic advantages. The increasing penetration of distributed energy sources can cause an increase in voltage variations in low voltage networks. To keep the voltage within limits defined by EN50160, voltage regulated distribution transformers could be used. Although mineral oil has been used as a dielectric fluid in transformers for many years, there are some environmentally friendlier alternatives – natural and synthetic ester-based fluids.

Issues of Safe Use of Plant-Based Food Supplements: A Review

Background: The widespread use of specialized food products, including plant-based dietary supplements, is determined by a rich variety of biologically active constituents. However, some plants containing such bioactive compounds as pulegone, menthofuran, estragole, methyleugenol, safrole, and thujone may cause adverse health effects. Objective: To review recent domestic and international scientific papers in order to substantiate the importance of regulating maximum permissible levels of monoterpene ketones (pulegone, menthofuran, and thujone) and alkenylbenzenes (estragole, methyleugenol, and safrole) in plant raw materials and plant-based nutritional supplements. Materials and methods: We used the keywords pulegone, menthofuran, methyleugenol, estragole, safrole, and thujone to search Scopus, Web of Science, PubMed, and RSCI abstract and citation databases and then applied information analysis and expert examination techniques to summarize research data published in Russian and English languages in 2001–2021. The initial sample consisted of 43 articles, of which 13 were excluded after initial screening. The selection criteria included availability of data on metabolism of the organic compounds in question, their levels in herbs and herbal teas, toxic effects on experimental animals, and potential adverse health effects in humans. We selected 30 full-text scientific publications and classified their data by the type of interventions. Results: The analysis of numerous studies of monoterpene ketones and alkenylbenzenes indicates a toxic effect of these groups of compounds on experimental animals. The International Agency for Research on Cancer (IARC) has classified pulegone, methyleugenol and safrole in Group 2B, which means that they are possibly carcinogenic to humans. Human health risks from plant-based alkenylbenzenes contained in dietary supplements are also demonstrated. Conclusion: Our findings prove the need to take appropriate risk management measures in order to limit the use of certain plant species containing high concentrations of biologically active substances posing threat to human health and to regulate their permissible levels in plant-based supplements.

Importance and Toxicity of Biogenic Amines in Fresh and Processed Foods

Biogenic amines are decarboxylation products of amino acids and naturally they occur in living organisms and are involved in various biological processes. Nitrogenous compounds such as histamine, tyramine, putrescine, cadaverine, agmatine, spermidine and spermine are called biogenic amines and are found in raw and processed foods. Besides its role in physiological activity in human health, high quantities in food may be hazardous. Consumption of biogenic amines beyond its maximum permissible level could result in nausea, respiratory distress, hot flush, sweating, heart palpitations, headache, bright red rash, burning sensations in the mouth and alterations in blood pressure. In addition to its toxicity, in foods containing abundant amount of protein, the high concentrations of these diamines are indicative for hygienic deficiencies in the postharvest unit operations of agricultural products. Therefore, it is crucial to control the formation of biogenic amines during food processing

The Contents of Some Trace Elements (As, Br, Cu, Hg, Se, and Zn) in Mytilus galloprovincialis Mussels From Agigea Port, Romania

This study aimed at assessing the accumulation of some trace elements (arsenic, bromine, copper, mercury, selenium, and zinc) in the soft tissue of Mediterranean mussels (Mytilus galloprovincialis) from the Black Sea, near Agigea Port. The mussel samples were collected on a monthly basis between February and June 2019 from two stations located in front of the Danube–Black Sea Canal lock, along the two artificial dikes. The mussels (260 samples) were divided into three classes according to their length: A (3−5.9 cm), B (6−8.9 cm), and C (9−12 cm). The concentrations (dry basis) of As (12.5 ± 3.0 mg/kg), Br (173.6 ± 53.9 mg/kg), Cu (11.2 ± 2.5 mg/kg), Hg (0.02 ± 0.02 mg/kg), Se (2.9 ± 1.1 mg/kg), and Zn (179.5 ± 2.5 mg/kg) were determined using spectrometric techniques. The mean daily values of the physicochemical parameters of seawater (temperature, salinity, pH, chlorophyll a content, and dissolved oxygen content) within the study area were reported. Higher element concentrations were generally found for mussels from size classes A and B compared with those of the larger and older mussels from class C. Principal component analysis (PCA) suggested that the phytoplankton represented an important source of As and Br for the smaller mussels collected in February (when the levels of seawater temperature were lower and those of pH and salinity higher) compared to the larger mussels collected in June. Moreover, the multivariate analysis suggested that Cu, Se, Zn, and Br originated from similar anthropogenic sources and their higher concentrations reported in February and June were obtained at lower levels of seawater salinity. The contents of Cu, Zn, Se, As, and Hg in the mussel soft tissue were lower than the maximum permissible levels.

Hygienic assessment of polyurethane coatings in the practice of drinking water supply

Introduction. For many years, two-component polyurethane coatings have been used as suitable systems for the protection and reconstruction of pipes in the practice of domestic drinking water supply. However, polyurethane can be a source of pollutants entering drinking water. Special attention in the hygienic assessment is paid to the main components of plastic, the released solvents and film-forming agents used in the formulation of the material. However, the definition of only priority components (taking into account Uniform sanitary requirements) does not provide complete information about the chemical stability of polymer materials during the hygienic assessment. Materials and methods. Eight different two-component polyurethane coatings of various manufacturers and manufacturers offered for use in drinking water supply are investigated in the work. The evaluation of these samples was carried out taking into account Uniform requirements (2010). Indicators that are not mandatory for the evaluation of polymer materials used in drinking water supply were also investigated. Results. Conducting a hygienic assessment of two-component polyurethane coatings shows fundamentally different chemicals to migrate into the model environment even from materials with the same type of components. When analyzing water extracts, from 9 to 40 organic compounds were identified at different temperatures. Most of them do not have the maximum permissible levels of their content in drinking water and there are no fully conducted toxicological studies of these chemicals to assess their safety for humans. There also were found three samples, from which inorganic components of cadmium and nickel migrated into distilled water above their maximum permissible values. Limitations. This study was conducted on the example of polyurethane coatings, as a particular example of the use of polymer materials in drinking water supply. It is necessary to conduct similar studies on other groups of polymers. Conclusion. At the moment, there are certain contradictions in the methodology and approaches to assessing the migration of chemicals from polymer coatings to drinking water. Therefore, their refinement and standardization is relevant, taking into account the increasing share of the use of polymer materials in human life.

Rat hematological parameters of subacute multifrequency electromagnetic next-generation cellular communications exposure

The cellular communication electromagnetic fields have become a significant physical environmental factor recently, which cannot but cause reasonable concern due to the possible adverse effects of human health. Experimental laboratory animal studies are an integral part of the development and substantiation maximal permissible levels, in which the blood system is an objective functional indicator of the electromagnetic field biological effects. Thus, the purpose of the research was to study the hematological parameters of the male and female rat blood of subacute multi-frequency electromagnetic exposure from cellular communication systems and possible long-term biological effects. The object of research was male and female Wistar line rats. There were multi-frequency 30-days electromagnetic field exposure with 500 μW/cm2 power density at 3.5, 28 and 37 GHz summary. Hematological parameters of peripheral rat blood of the experimental and control groups were determined at the end of 30 days of exposure and 30 days after exposure. 30 days exposure did not lead to statistically significant changes in the blood cell composition in either male or female rats compared with sham exposure. In post exposure period (30 days after), significant changes in hematological parameters shown female rats only, which consisted in a decrease in the average content (MCH) and the average concentration (MCHC) of hemoglobin (Hb) in erythrocyte (RBC), the level of leukocytes (WBC), lymphocytes (LYM) and an increase in monocytes (MON). There were no statistical changes in all hematological parameters in male rats. The research results suggest the development of aftereffect adaptive reactions in rats upon completion of subacute electromagnetic exposure and their correlation to the effect depending on the sex of the animal.

MICROBIOLOGICAL QUALITY CONTROL OF FEED FOR FARM ANIMALS IN UKRAINE, 2021

In animal feed productions in conditions of nowadays competition in the markets, a successful prospect is possible only if the animal feed production would meet the needs of customers. The quality of feed have to meet the requirements of current regulations: standards, specifications, regulations, directives, etc. [1]. A lot of countries are enacting laws that allow uniform standards to be set and feed to be verified. The quality and safety of feed further affects the quality of agricultural products of animal origin, which in turn directly affects the health of consumers of these products [2]. Safety indicators are important, according to microbiological criteria.With a view to ensuring animals with quality feed in Ukraine, Order 131 of 19.03.2012. «On approval of the list of maximum permissible levels of undesirable substances in feed and feed materials for animals» with changes number 550 from 11.10.2017 [3].

Surveillance for ototoxicity in platinum-based chemotherapy using mobile health audiometry with extended high frequencies.

This study investigated mobile health enabled surveillance in ototoxicity. This was a longitudinal study of 32 participants receiving chemotherapy. Baseline and exit audiograms that included conventional and extended high frequency audiometry were recorded within the patient's treatment venue using a validated mobile health audiometer. Average hearing thresholds at baseline were within the normal range (81.2 per cent left; 93.8 per cent right), reducing at exit testing (71.9 per cent left; 78.1 per cent right). Half of participants presented with a threshold shift according to ototoxicity monitoring criteria. The frequencies affected the most were between 4000 and 16 000 Hz, with left ears significantly more affected than right ears. Noise levels exceeded the maximum permissible ambient noise levels in up to 43.8 per cent of low frequencies (250-1000 Hz). Mobile health supported audiometry proved to be an efficacious tool for ototoxicity monitoring at the treatment venue. Changes in hearing ability over time could be tracked, improving surveillance in patients with full treatment schedules.

Human health risk assessment of heavy metals from meat and offal of reindeer and cow in the Far North of European Russia.

This study aimed to compare the concentrations of heavy metals in reindeer and cow meat and offal originating from the Nenets Autonomous Okrug, Northwestern Russia, and to assess the risk to the health of the indigenous population associated with heavy metal intake due to the consumption of reindeer and cow. Lead, cadmium, mercury, and arsenic concentrations were measured in 39 muscle, 15 liver, and 14 kidney samples from reindeer and 33, 18, and 12 corresponding samples from cow in 2014-2016 using atomic absorption spectrometry. Estimated daily intake of investigated heavy metals, hazard quotient, hazard index and cancer risk were calculated. Mean cadmium and mercury concentrations in reindeer liver and kidney exceeded the maximum permissible levels for bovine animals. However, the estimated daily intakes of heavy metals through consumption of reindeer and cow meat and offal were lower than tolerable daily intakes. Hazard quotient and hazard index values for heavy metals in reindeer and cow samples were <1. Hazard index values were in descending order: reindeer kidney (0.389)>reindeer muscle (0.382)>cow muscle (0.088)>reindeer liver (0.051)>cow kidney (0.012)>cow liver (0.004). The cancer risk related to the consumption of reindeer and cow meat and offal did not exceed acceptable levels. There is no human health risk associated with heavy metal intake due to the consumption of reindeer and cow meat and offal originating from the Nenets Autonomous Okrug.

Mapping of Fuel Wood Types Used in Smoking Fish in Relation to Occurrence of PAHs in Smoked Fish in Nigeria

Polycyclic aromatic hydrocarbons (PAHs) are organic contaminants present in fuel woods which are hazardous to human health. The aim of the study is to determine the level of PAHs present in fuel woods used for smoking fish in Nigeria. Samples of fuels collected all over Nigeria were categorized into Hard, Soft and Starters. Four samples were extracted and analyzed using gas chromatography attached with a mass spectrophotometer. The result showed that all the fuelwoods have PAHs below maximum permissible level. Teak wood has high level of PAHs in Naphthalene 0.048 ± 0.000132, Acenaphthylene 0.0013 ± 0.00005, Fluorene 0.0105 ± SE-05, Pyrene 0.0105 ± SE-05, Fluoranthene 0.0119 ± 0.0001, Triphenylene 0.0011 ± 1E-04, Benz(a)anthrax 0.0008 ± SE-05. The order of increase of hazard (PAHs) for the fuel woods are Tectona spp &gt; Azadirachta spp &gt; Mangifera spp &gt; Anacardium spp. When the four fuel woods were used to smoke the same fresh Clarias gariepinus with the same equipment, it was revealed that all were having a high level of PAHs above maximum permissible limit. Fish smoked with Anacardium spp of wood has the highest level of PAHs. Therefore, excess use of Anacardium spp of woods should be averted when smoking fish because of the lipophilic nature of PAHs.

State of metabolic processes in cattle under the influence of biotic contaminants of feed

Control of feed contamination by micromycetes and bacteria at all stages of their preparation, storage, and feeding of farm animals is an acute issue of feed safety and one of the principal measures that create an opportunity to prevent their negative impact on animal health. Therefore, the study aimed to investigate the state of metabolic processes in cattle of different physiological groups under the influence of biotic feed contaminants. The material for the research was grain fodder and coarse grinding grain of local production, roughage used on the farm. Veterinary and sanitary condition of grain products was established based on organoleptic, toxico-biological and microbiological studies. To determine the indicators of the state of metabolic processes, 3 groups of cows (n = 5–7) with different physiological conditions were formed: group I — non-pregnant cows, group II — pregnant animals with normal pregnancy, group III — cows after miscarriage. Biochemical parameters (level of total protein, albumin, globulins, vitamins A and E) in blood serum samples were determined spectrophotometrically by conventional methods. The study of the content of inorganic elements in the aggregate samples of bovine sera was performed using an X-ray spectrometer ‘Spectroscan MAX’. Laboratory studies have proven the presence of biotic contaminants in the feed base of the experimental farm. Exceedance of maximum permissible levels of feed contamination (max 16.50×104 CFU/g when MPL 5.0×104 CFU/g) by toxin-forming micromycetes (due to the genera Fusarium, Aspergillus, Penicillium, Mucor, and Rhizopus; a total of 24 isolates of microscopic fungi were isolated, which showed high toxicity in 11.3% and weak — in 20.1% of samples) and total bacterial contamination (max 18.7×105 CFU/g when MPL 5.0×105 CFU/g), in the structure of which coliform bacteria and Salmonella enterica were isolated. In cattle that consumed feed with an excess of biotic contaminants, disorders of the digestive tract (diarrhea) and reproductive capacity (abortions in the first half of pregnancy) were observed and metabolic disorders were found in cattle: increased Iron (on average 1.5 times) and Bromine (on average 1.6 times) levels, a decrease in the concentration of vitamin A (by 17.4–39.8%), and vitamin E (by 10.0–12.5%), most pronounced in cows after abortion and pregnant cows, respectively, Manganese (on average by 12.5%) and Selenium (by 30.7%)

Trace Elements and Arsenic Speciation of Field and Market Rice Samples in contrasting Agro-climatic Zones in Sri Lanka

Rice is a major source for micro-elements for the Sri Lankan population, across all agro-climatic zones. This current study was conducted to investigate the variation of the metal(loid)s and As speciation in rice grains collected from wet, intermediate and dry zones of Sri Lanka. Field rice (brown rice) and market rice (polished rice) samples were analysed for total elemental profile and As speciation using ICP-MS and IC-ICP-MS, respectively. As, Cd, Co, Fe, Mn, Mo, Rb, Se, Sr and Zn in field grain samples varied across climatic zones. Highest median Cd, Cu, Mo, P, Rb, Se and Zn from wet zone; Co, Fe, Mn from intermediate zone; and As and Sr from dry zone were reported. Field rice (As, 0.3%; Cd, 1%) and market rice (As, 0%; Cd, 3%) samples exceeded maximum permissible levels of As and Cd. However, higher concentrations of both fields, 18% samples for As and 21% samples for Cd, and market, 7% samples for As and 38% samples for Cd, rice exceeded the recommended permissible levels of As and Cd in infant food according to EU regulations. The high per capita consumption and the chronic exposure to As and Cd through rice may cause adverse effects on Sri Lankan children and adults.

Estimation of Radioecological State at the Objects of the Former Novotroitsk Mining Department, Baley (Zabaykalsky Region)

The results of dosimetric measurements which were carried out on the territory of the former Novotroitsk mining department quarry (Baley, Zabaykalsky region) are obtained. The map of radioactive contamination of the quarry territory is presented. A number of objects on the explored area where the gamma ray dose ambient equivalent is exceeds the maximum permissible level of 0.60 mSv/h were identified. The specific effective activity and chemical composition of a soil sample taken at one of the contaminated sites were determined. It is detected that the main source of radioactivity is 232Th nuclide, which is part of the mineral monazite. The possibility of effective concentration of thorium-containing minerals by gravitational separation was shown. The main factor of the spread of radioactive contamination is water erosion of soils from the walls of the quarry.

Determining patterns in the generation of magnetic fields when using different arc welding techniques

This paper reports a study into the levels of magnetic fields induced by arc welding equipment in various ways in order to assess their impact on the body of welders. It is known that welders are exposed to a magnetic field of high intensity. Depending on the welding technique and the type of welding equipment, it may exceed the maximum permissible levels (MPL). Note that new Ukrainian sanitary standards for magnetic fields have been introduced, which regulate their levels depending on the frequency range. Therefore, it became necessary to carry out their hygienic assessment according to the new standards in order to devise appropriate methods for protecting welders. To this end, it was required to choose a new generation of devices to determine the intensity of magnetic fields induced by welding equipment. Based on the analysis of the constructed oscillograms and spectrograms of magnetic fields, it was found that semi-automatic welding with a metal electrode in carbon dioxide is characterized by an increased level of magnetic field in the frequency range of 50‒1000 Hz. With automatic arc welding under the flux, there are no excess of the maximum permissible levels of individual harmonics of the magnetic field but there is an excess of the total value of all harmonic components of the magnetic field. Manual arc welding with direct current involving a non-melting electrode in argon is characterized by a moderate level of magnetic field in workplace. During manual arc welding with coated electrodes, the exceeded level of the magnetic field is observed only on the electrode cable itself. It is shown that the spectral composition of the magnetic field signal is determined mainly by the welding technique itself, the peculiarities of arc combustion, and the nature of the transfer of electrode metal in the arc gap, as well as the initial parameters of the power supplies of the welding arc