Maximum Allowable Concentration Research Articles

Analytical Method Development and Dermal Absorption of 4-Amino-3-Nitrophenol (4A3NP), a Hair Dye Ingredient under the Oxidative or Non-Oxidative Condition.

The chemical 4-amino-3-nitrophenol (4A3NP) is classified as an amino nitrophenol and is primarily utilized as an ingredient in hair dye colorants. In Korea and Europe, it is exclusively used in non-oxidative or oxidative hair dye formulations, with maximum allowable concentrations of 1% and 1.5%, respectively. Despite this widespread use, risk assessment of 4A3NP has not been completed due to the lack of proper dermal absorption data. Therefore, in this study, both the analytical method validation and in vitro dermal absorption study of 4A3NP were conducted following the guidelines provided by the Korea Ministry of Food and Drug Safety (MFDS). Before proceeding with the dermal absorption study, analytical methods were developed for the quantitation of 4A3NP through multiple reaction monitoring (MRM) via liquid chromatography-mass spectrometry (LC-MS) in various matrices, including swab wash (WASH), stratum corneum (SC), skin (SKIN, comprising the dermis and epidermis), and receptor fluid (RF). These developed methods demonstrated excellent linearity (R2 = 0.9962-0.9993), accuracy (93.5-111.73%), and precision (1.7-14.46%) in accordance with the validation guidelines.The dermal absorption of 4A3NP was determined using Franz diffusion cells with mini-pig skin as the barrier. Under both non-oxidative and oxidative (6% hydrogen peroxide (H2O2): water, 1:1) hair dye conditions, 1% and 1.5% concentrations of 4A3NP were applied to the skin at a rate of 10 μL/cm2, respectively. The total dermal absorption rates of 4A3NP under non-oxidative (1%) and oxidative (1.5%) conditions were determined to be 5.62 ± 2.19% (5.62 ± 2.19 μg/cm2) and 2.83 ± 1.48% (4.24 ± 2.21 μg/cm2), respectively.

Assessment of the suitability of greensand filtration for Mn removal for private wells

Greensand filtration is a common treatment option for manganese, sulfide, and iron removal; poor maintenance, however, can compromise effectiveness and even lead to increased post-treatment Mn concentrations. A private drinking-water well in exceedance of Health Canada’s maximum allowable concentration for Mn was sampled over a 1-year period to assess Mn removal via greensand filtration. Mn concentrations post-treatment were on average twofold higher than raw well water prior to media change. Reducing conditions, evidenced by negative oxidation–reduction potential (ORP) of the effluent, were central to generating soluble Mn(II). Monitoring revealed that water usage patterns caused variability in post-treatment Mn, with peak concentrations (>3.5× higher than influent water) observed after a 7-day idle period. As inadequate oxidant addition can lead to reducing conditions, monitoring ORP may facilitate proxy surveillance for Mn release. Findings underscore the importance of human factors (e.g., aesthetic concerns, barriers to maintenance, perceived risk) when evaluating overall benefits and drawbacks of treatment systems.

Impact of Composition Ratio on the Expansion Behavior of Polyurethane Grout.

Different formulations of foaming polyurethane grout offer controlled expansion rates. This is crucial for precision in filling voids without exerting excessive pressure on surrounding structures, which could potentially cause damage. This study focuses on the impact of composition on the expansion performance of tailor-made polyurethane grouting materials. Initially, multiple unknown chemical reaction kinetic parameters were identified by combining free expansion tests, which involved measuring density and temperature changes, with the particle swarm optimization algorithm. A numerical simulation, integrating chemical kinetic models and fluid flow equations, was established to replicate the free expansion process of polyurethane grout in a cup, aligning with our experimental results. Subsequently, we analyzed the polymerization process of polyurethane grout with varying compositions to determine the effect of composition ratios on grout expansion. Our findings reveal that the expansion ratio of foaming polyurethane is predominantly influenced by the concentrations of physical and chemical foaming agents, followed by isocyanate concentration. Polyol, in contrast, exerts a relatively minor influence. Furthermore, the solubility of the physical foaming agent in the grout determines both its maximum allowable concentration and its maximum contribution to volume increase. This study provides valuable insights for the design and selection of polyurethane grout components tailored to diverse applications.

Electrochemical detection of 4(5)-methylimidazole in aqueous solutions

4(5)-methylimidazole (4-MeI) is a potential carcinogen widely used in food colours. EU regulations specify a maximum allowable concentration of 200 ppm for 4-MeI in caramel colours. This study reports an electrochemical determination technique for 4-MeI in caramel colours for the first time. The effect of pH and interference from air were studied to optimize the detection conditions on a glassy carbon electrode in aqueous alkaline solutions using square wave voltammetry (SWV) technique. The concentration of 4-MeI was quantitatively measured down to 10 μM (∼0.8 ppm). Traditional methods such as HPLC, GC, spectrometry and immunoassays involve either expensive instrumentation and reagents or time consuming preparation and detection processes. This study demonstrates the possibility of rapid and simple electrochemical determination of (4-MeI) in food colours with minimum workup using a portable potentiostat.

Influences of Heavy Metals in Water Treatment Chemicals on Drinking Water Quality and Risk Management

Water treatment chemicals (WTCs) are important raw materials during the drinking water production process. Occasionally unqualified WTCs with heavy metals were provided to Water Treatment Plant（WTP） by supplier during emergency situation，such as earthquake, typhoon and city block for epidemic disease, just because it cannot obtain the qualified WTCs. The harmful heavy metals in WTCs may expose a certain health risk to the quality of drinking water. In this paper, the influence of heavy metals in WTCs on the quality of drinking water was explored and the feasible management measures are proposed, taking the ILha Verda Water Plant (IVP) in Macao as an example. The study was based on the testing results of heavy metals in WTCs and treated water from 2017 to 2022 in IVP. A series of mathematical models were established to evaluate the content of heavy metals in water brought by WTCs. The removal rates of the water treatment process to the heavy metals were calculated at same time. The maximum allowable concentrations of heavy metals in WTCs were calculated and accessed. The results show that the drinking water is safety if the heavy metals in unqualified WTCs are under the maximum allowable concentrations. Then it is proposed for the classification of WTCs and risk management. The study will provide theoretical and technical support for water quality safety supervision and water supply management.

Zastosowanie chromatografii gazowej do oznaczania 1,4-dioksanu w powietrzu na stanowiskach pracy

1,4-Dioxane is a volatile liquid with a weak odor that dissolves well in water and most organic solvents. As a flammable liquid it poses a fire hazard. 1,4-Dioxane is unstable at increased temperature and pressure and can form explosive mixtures. It is mainly used as a solvent in the production of other chemicals, as a solvent for printing inks, coatings and adhesives, and as a laboratory reagent. According to the Regulation of the European Parliament and the Council (WE 1272/2008), 1,4-dioxane is classified as a carcinogen, flammable, eye and respiratory irritant. This article presents a method for the determination of 1,4-dioxane in workplace air, revised due to a proposed change in the maximum allowable concentration (MAC) value for this substance. The method involves adsorption of 1,4-dioxane on activated carbon, desorption with a mixture of propan-2-ol and carbon disulfide, and chromatographic analysis (GC-FID) of the resulting solution. The method allows for the determination of 1,4-dioxane in the concentration range of 2.2 to 44 mg/m3 (MAC 22 mg/m3 ) or 0.73 to 14.6 mg/m3 (MAC 7.3 mg/m3 ), i.e. 1/10 to 2 of the proposed value of the maximum allowable concentration. The method has been validated in accordance with PN-EN 482. This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Oznaczanie antymonu i jego związków w powietrzu na stanowiskach pracy

Antimony is used as an additive in font and bearing alloys along with other metals. Antimony in metallic form is not classified as a health hazard, while its salts have been so classified. Some antimony compounds have been classified as carcinogens. The applicable value of the maximum allowable concentration (MAC) in air at workplaces is 0.5 mg/m3 (MRPiPS ordinance, 2018). The purpose of this study was to develop a method for the determination of antimony for occupational exposure assessment in the range of 1/10–2 of the proposed MAC values. The method consists of collecting antimony and its airborne compounds from an MCE filter, mineralizing the filter in aqua regia at 150°C, then determining the antimony content in the sample using atomic absorption spectrometry (AAS) with flame atomization. The method for the determination of antimony is presented in the form of an analytical procedure, which is included in the appendix. The scope of the article includes health and environmental health and safety issues that are the subject of research in health sciences and environmental engineering

Water quality aspects from Spanish sites to support managed aquifer recharge (MAR) guidelines not based on maximum allowable concentration standards

Most countries that have technical guidelines or regulations for artificial recharge or managed aquifer recharge (MAR), that include water quality aspects are based on the establishment of standards or Maximum Allowable Concentrations (MACs) to regulate the quality of the water percolated or injected into an aquifer. The number of parameters in these guidelines vary considerably (from 6 in Spain to 156 in the USA) and often apply to all aquifers within administrative boundaries (e.g., national territory), regardless of the nature of the receiving medium, the depth of the water table, and other key factors. Eleven MAR systems in Spain have been studied (eight operational and three experimental, with limited number of data from three sites), characterising both, the recharge water quality and the water resulting from the interaction processes recharge water-soil-unsaturated zone-saturated zone of the aquifer. In all cases, an improved effect on groundwater quality is observed, even though some parameters in the recharge water don’t comply with the standards employed in some European countries, where this article focuses. The article suggests that regulating water quality for MAR through MACs at national level gives room for another alternative approach specific for each site. It might be recommendable to establish local standards at the regional or aquifer-wide level to better reflect the diversity of groundwater occurrence. As per the article, sectoral water authorities could receive more decision-making power on granting permits for MAR based on the quality of the hydrogeological and risk studies for each request. This would help reduce the application of the precautionary principle when in granting permission.

Effects of Ginger on Growth Indices and Pb Bioaccumulation of Tomato Fruits Cultivated in Lead and Spent Engine Oil-Contaminated Soils

Good soil is needed for public health and this research studies lead concentrations of tomato planted in different soil samples in Wukari, Taraba state, Nigeria (with 50mg/kg simulated and non-simulated contamination) labelled groups A-H. Two weeks-old tomato seedlings were transplanted to triplicates of soils pots labelled A: normal soil, B:Ginger treated (positive control), three negative controls; C:lead contaminated; D Spent Engine Oil (SEO) contaminated, and E:Pb+SEO containing soil, F:Lead contaminated+ginger treatment, G: SEO contaminated+ginger treatment, H:lead+SEO contaminated+ginger treatment. The lengths, circumferences and weights of 36 tomato fruits per plant pot were measured at random. Lead uptake and bioaccumulation were also assessed in tomato fruits derived from each group. Tomato fruits in group E weighed highest (15.41±7.81g) while those in group H had the lowest weight (12.02±6.69g). The longest and the highest average tomato fruit circumference were recorded in group D (5.61±2.66cm and 6.15±2.93cm) respectively. Conversely, group H presented the shortest mean tomato fruits with 4.19±2.45cm and lowest fruit circumference (4.49±2.34cm). Bioaccumulation of lead was highest in tomatoes of group E with 1.79±0.47ppm and the lowest was derived from group A:normal soil with 0.68±0.13ppm on average each. The lead concentrations of all groups exceeded permissible limits specified in WHO/FAO Standards (0.01 ppm) as well as the maximum allowable concentration of 0.02 ppm by EU and 0.05 ppm limit set by USEPA suggesting a public health concern.

WITHDRAWN: Trace metals translocation from soil to plants: Health risk assessment via consumption of vegetables in the urban sprawl of a developing country

The study was conducted at 15 locations around the thermal power plant of Patuakhali district at the coastal area of Bangladesh to determine trace elements in vegetable and assess risk of toxicity. Eight vegetables, namely, tomato (Solanum lycopersicum L.), radish (Raphanus raphanistrum L.), bean (Phaseolus vulgaris L.), brinjal (Solanum melongena L.), bottle gourd (Lagenaria siceraria L.), red amaranth (Amaranthus cruentus L.), arum (Arum maculatum L.) and lady's finger (Abelmoschus esculentus L.) were analyzed for nine trace metals (Cr, Ni, Cu, As, Cd, Pb, Fe, Mn and Zn) to assess contamination load of trace elements in agricultural soil, and health risks posed from vegetable consumption. The mean concentrations of Cr, Cr, Ni, Cu, As, Cd, Pb, Fe, Mn, and Zn in soil were 16.6, 14.8, 5.8, 1.3, 0.72, 9.7, 55261, 456.1, and 105.8 mg/kg, respectively. Average concentrations of As, Cd, and Pb in vegetable species were higher than the maximum allowable concentration (MAC), indicating vegetables species were contaminated by these elements and may pose potential risk to human. Fe, Mn, Zn, Cr, Cu, Pb, and As in soil and vegetables of the study area may arise from anthropogenic activities. The present study suggests that surface soil used for vegetables production should be continuously monitored to check the transfer of toxic metals into the vegetables to minimize the adverse health impacts on consumers and potential threats to food safety.

Water quality analysis of Sumurup River in Gunungkidul, Indonesia, using the water quality index

Sumurup River is one of the rivers in Gunungkidul, Indonesia, that continuously flows water throughout the year and traverses different land use types. Consequently, it receives numerous waste inputs. Given the limited water resources in the area, it is necessary to assess the water quality regularly. Moreover, this river was previously a drinking water supply, but it can now only be used for purposes with lower requirements, e.g., bathing and washing. The water quality was assessed using three scenarios with different number of parameters in the composite and two indices: the Indonesian Modification of Water Quality Index (INA-WQI) and the Weighted Arithmetic Water Quality Index (WA-WQI). Parameters observed were pH, DO, BOD, COD, NH3, NO3, total phosphate, TSS, TDS, and fecal coliform. Results showed that the safe limits of pH, BOD, COD, NH3, NO3, total phosphate, TSS, and fecal coliform for drinking water (Class I) were exceeded at several sampling points. In contrast, DO and TDS were below their maximum allowable concentrations at all points. WQI assessment produced varying index values categorized as fair to good (INA-WQI) or excellent to unsuitable for drinking (WA-WQI). Further, the different composite scenarios had a significant effect on WA-WQI but not on INA-WQI scores.

The Effects of Ambient Temperature and Atmospheric Humidity on the Diffusion Dynamics of Hydrogen Fluoride Gas Leakage Based on the Computational Fluid Dynamics Method.

In order to investigate the impact of environmental temperature and atmospheric humidity on the leakage and diffusion of hydrogen fluoride (HF) gas, this study focused on the real scenario of an HF chemical industrial park. Based on the actual dispersion scenario of HF gas, a proportionally scaled-down experimental platform for HF gas leakage was established to validate the accuracy and feasibility of numerical simulations under complex conditions. Using the validated model, the study calculated the complex scenarios of HF leakage and diffusion within the temperature range of 293 K to 313 K and the humidity range of 0% to 100%. The simulation results indicated that different environmental temperatures had a relatively small impact on the hazardous areas (the lethal area, severe injury area, light injury area, and maximum allowable concentration (MAC) area) formed by HF gas leakage. At 600 s of dispersion, the fluctuation range of hazardous area sizes under different temperature conditions was between 3.11% and 13.07%. In contrast to environmental temperature, atmospheric relative humidity had a more significant impact on the dispersion trend of HF leakage. Different relative humidity levels mainly affected the areas of the lethal zone, light injury zone, and MAC zone. When HF continued to leak and disperse for 600 s, compared to 0% relative humidity, 100% relative humidity reduced the lethal area by 35.7%, while increasing the light injury area and MAC area by 27.26% and 111.6%, respectively. The impact on the severe injury area was relatively small, decreasing by 1.68%. The results of this study are crucial for understanding the dispersion patterns of HF gas under different temperature and humidity conditions.

COMPARATIVE ANALYSIS OF THE ELEMENTAL COMPOSITION OF ORGANS OF PROMISING SPECIES OF THE GENUS IRIS L. (IRIDACEAE)

Plants of the genus Iris L. are promising medicinal raw materials with significant biological and pharmacological activity. The quality of plant raw materials depends on the accumulation and distribution of potentially hazardous chemical elements in the plant body. The aim of this work was a comparative study of the accumulation and transfer of elements through the organs of plants of the genus Iris L. (Iridaceae). The content of As, Cd, Cr, Cu, Mn, Ni, and Pb in different parts of I. orientalis, I. pseudacorus, I. sibirica and I. spuria plants was analyzed by atomic absorption. It has been established that in the absence of soil pollution, irises accumulate arsenic in concentrations exceeding the maximum allowable. The accumulation of chromium in the raw material was also above the maximum allowable concentration for a number of study options. The efficiency of element transfer from the soil to the root system varied significantly (bioaccumulation factor 0.2–4.4). Iris rhizomes absorbed nickel most actively. The assimilation ability of the roots is also clearly expressed in relation to Pb, As, Cr, Cu, Mn. Depending on the element, accumulation in leaves is species-specific. The carrying capacity of the peduncle is most pronounced in I. sibirica, the barrier capacity is most pronounced in I. orientalis. Various types of translocation of elements in organs were revealed: acropetal, uniform, basipetal. All studied species are characterized by acropetal distribution of Pb (translocation factor >1) and uniform distribution of Mn. The location of Cd may vary depending on the species. Cu is concentrated in the roots (I. orientalis, I. sibirica, I. spuria) or evenly distributed (I. pseudacorus). The revealed patterns of accumulation and distribution of elements in the organs of plants of the genus Iris make it possible to carry out a prognostic assessment of the quality of raw materials to obtain safe products.

Phthalates in Surface Waters of the Selenga River (Main Tributary of Lake Baikal) and Its Delta: Spatial-Temporal Distribution and Environmental Risk Assessment

The Selenga River provides about half of the water and chemical runoff into Lake Baikal and plays an important role in the sustainability of the ecosystem of this large natural freshwater lake. Phthalate esters (PAEs) are organic compounds that can disrupt reproductive and endocrine systems. This study focused on investigating the distribution of six priority phthalates in the Selenga River and its delta utilizing SPE-GC/MS. The study found that the highest levels of Σ6PAE were observed during the high-water years, 2021 and 2023, and were evenly distributed along the river from the sampling sites upstream of Ulan-Ude to the delta channels. In contrast, the mean annual Σ6PAE content was relatively low in the low water period of 2022. Dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) are the two dominant phthalates found in the surface waters of the Selenga River and delta channels. In 2021, the average total concentration of six phthalates (Σ6PAE) ranged from 8.84 to 25.19 µg/L, while in 2022 it ranged from 0.45 to 4.01 µg/L, and in 2023 it ranged from 5.40 to 21.08 µg/L. The maximum level for the sum of phthalates was 61.64 µg/L in 2021, 13.57 µg/L in 2022, and 30.19 µg/L in 2023. The wastewater treatment facilities in Ulan-Ude were identified as a stable local source of phthalates. In some cases, PAE concentrations exceeded maximum allowable concentrations, particularly for DEHP. This could have adverse effects on aquatic organisms.

Human health risk assessment and uncertainty analysis of silver nanoparticles in water.

Despite frequent detection in environmental waters, literature which quantifies the health risk of silver nanoparticles (Ag NPs) through oral ingestion is scarce. This study compiled literature data to find the removal of Ag NPs from different treatment schemes (i.e., natural, engineered, or hybrid). Ag NP concentrations were found either in surface water or in groundwater based on where the effluent of treatment schemes was discharged, i.e.,either in surface water or in groundwater. Monte-Carlo simulation was carried out for probabilistic assessment of health risks for children for two hypothetical exposure scenarios: (a) ingesting river water while swimming and (b) drinking groundwater. Bio-accessible fraction, dietary metal adsorption factor, and concentrations of silver ions were incorporated to simulate realistic situations. Different treatment schemes were ranked for their nanoparticles' removal efficiency with respect to (i) exceedance probability from guideline value and (ii) health risk to children. Hybrid treatment combinations, i.e., conventional primary and secondary treatment units followed by nature-based units (constructed wetlands and soil aquifer treatment), were ranked the best. The health risk value was found to be less than 1, with the 99th percentile value less than 10-3 in all cases. The maximum allowable concentration of Ag NPs was found to be as low as 1.43 mg/L for groundwater, suggesting probable potential for risk. Uncertainty analysis revealed that the uncertainty of the influent NPs concentration in raw wastewater contributes > 99% to the variance of the hazard index. The results of this work indicate that the use of natural treatment technologies with existing engineered treatments provides higher nanoparticle removal from wastewater without the requirement of any tertiary treatment unit.

Ecological threshold of phosphorus load in Baiyangdian Lake based on a PCLake model and ecological network analysis

Ecological thresholds are a useful indicator for implementing ecological management. Many studies determine the thresholds for nutrient loads in lakes based on the maximum allowable concentration of chlorophyll a (Chla), although this neglects the overall performance of the ecosystem. A PCLake model of Baiyangdian (BYD) Lake in northern China was constructed with six ecological network analysis (ENA) indicators that characterized the ecosystem function, system maturity, and food web structure to quantify the overall status of the BYD ecosystem. To my knowledge, this is the first study on the system level responses of the BYD Lake to phosphorus load interference. Different phosphorus load scenarios were designed to simulate the ecological responses of BYD Lake. The simulated results were employed to calculate the ENA indicators. Ecological thresholds were determined through the driving response relationship between the phosphorus load gradient and the ENA indicators. The results show a non-linear transition response of ENA indicator under phosphorus load gradient. As phosphorus load increases, D/H, SOI, and FCI decreases while A/DC, TPP/TR, and TPP/TB increases. This indicates that the overall structure and function of the ecosystem will deteriorate if phosphorus load increases. The phosphorus load thresholds for the overall performance of BYD Lake were 0.50–1.32 mg m−2 d−1, slightly wider than that of Chla (0.53–1.26 mg m−2 d−1). The model results clearly indicate that there is a time-lag phenomenon at the switch points in the response of ENA indicators compared to that of single functional group. In addition, the A/DC, TPP/TR, SOI, and FCI present more time-lag than that of other ENA indicators. These time-lag effects provide a particular opportunity for biodiversity conservation. Therefore, a possible management strategy is proposed to combine system-level and function group-level thresholds, with the ENA-based threshold as the bottom line and the phytoplankton's threshold as the early-warning indicator. This design is expected to be more precise and efficient, by exploiting the advantages of two thresholds, and may benefit for ecological management practices.

ВЛИЯНИЕ НЕКОТОРЫХ ЗАГРЯЗНЯЮЩИХ ВЕЩЕСТВ НА НЕКТОБЕНТИЧЕСКИХ РАКООБРАЗНЫХ

Background. Ingress of pollutants in water bodies, both direct and from the catchment area, is constantly increasing. It creates an escalating threat to aquatic ecosystems and humans as consumers of water and aquatic biological resources, which contributes to the relevance of the monitoring and regulation of water pollution. This work is aimed at the evaluation of the effect of various toxic substances and pollutants on the survival of the amphipod Hyalella azteca in a chronic experiment. Methods. This study has been carried out according to the standard toxicological methods. Results. This paper presents the data on the influence of pollutants of various nature (sodium hydrogen phosphate, sodium sulfate, zinc complex of 2-Phosphono-1,2,4-butanetricarboxylic acid, dimethyl sulfide) on the Hyalella azteca Saussure, 1858 crustaceans. Hyalella azteca have found a wide application in biotesting; however, these crustaceans are not used in the system of fisheries regulation in Russia. The maximum allowable and threshold concentrations of the investigated substances in the aquatic environment have been established for Hyalella azteca using the experimental approach. The maximum allowable concentration (MAC) of sodium hydrogen phosphate in the phosphorus equivalent was 1.0 mg/L, its threshold concentration was 2.5 mg/L; the MAC of sodium sulfate in the sulfate anion equivalent was 750 mg/L, its threshold concentration was more than 750 mg/L; the MAC of the zinc complex of 2-Phosphono-1, 2,4-butanetricarboxylic acid was 10 mg/L, its threshold concentration was 100 mg/L; the MAC of dimethyl sulfide was 10 mg/L, its threshold concentration was 20 mg/L. Conclusion. The amphipods H. azteca are moderately sensitive to pollutants. Among all investigated substances, the most toxic for H. azteca was sodium hydrogen phosphate.

Hardening of gear teeth depending on the concentration of abrasive particles in the transmission oil

The article deals with the issues of determining the life and limiting concentration of abrasive particles in the oil of transmission units, depending on the type of hardening of gear teeth. Resource was determined after volume hardening, hardening by current of high frequency and cementation by hardness of gears materials, on the friction machine on the samples which have been made of gears material, working in oil with abrasive particles, considering coefficient of acceleration at test. Maximum allowable concentration of abrasive particles in machine oil, were estimated on the basis of expression for calculation of wear rate, providing the set life, maximum allowable wear depending on modulus of gearing, hardness of gearing material, size of abrasive particles, geometrical and kinematic parameters of gearing.

Реакция Iba-1+ и CD68+ макрофагов печени лабораторных крыс на двухмесячное поступление водорастворимого кремния

Introduction. Silicon compounds are widely used in industrial production; therefore, people are highly likely to have constant contact with this element. Hepatic macrophages are crucial in maintaining homeostasis in the liver; thus, investigating their reaction can provide new information on their possible participation in the inflammation induced by silicon supplied with water. The aim was to explore how Iba1+ and CD68+ liver cells in laboratory rats respond to the intake of silicon with drinking water at a concentration of 10 mg/l during two months. Materials and methods. Laboratory rats were divided into 2 groups: the control group (n=5) received drinking bottled water ad libitum, whereas the experimental one was given the same water with addition of sodium metasilicate nonahydrate (Na2SiO3 × 9 H2O) at a concentration of 10 mg/l in terms of silicon. This corresponded to the maximum allowable concentration, according to SanPiN 2.1.4.1074-01 in force at the time of the experiment. The animals were withdrawn from the experiment 2 months after had begun. The liver was removed and fixed in 10% neutral formalin and embedded in paraffin according to the standard protocol. Iba1+ and CD68+ structures were detected with immunohistochemical and immunofluorescence methods using specific antibodies. Results. We compared the expression patterns of the two macrophage markers and detected that in the experimental group, the median area of Iba1-positive cells in the livers of rats had a 0.87-time decrease compared to that in the control group (p=0.000006). The experimental group showed an increase in the number of Iba1+ and CD68+ cells (p=0.02 and p=0.01, respectively). We revealed that in the experimental group, immunofluorescence in Iba-1+ liver macrophages decreased (p=0.01), whereas that in CD68+ macrophages increased (p=0.27). Conclusion. The intake of water-soluble silicon at a concentration of 10 mg/l activates liver macrophages in a relatively short period of exposure (two months). Therefore, the safety of silicon compounds in the conditions of their constant supply should be studied more thoroughly.

Assessment of Nutrient Minerals and Potentially Toxic Elements in a Bangladesh-Origin Rice Cultivar (Oryza sativa cv. BR11) and Associated Health

Rice contributes significantly to both food security and livelihoods in Bangladesh. Despite challenges such as an immense population growth rate and decreased arable land since gaining independence, Bangladesh has attained self-sufficiency in rice production by adopting modern rice varieties (MRVs). However, not all introduced MRVs have gained widespread acceptance among farmers due to concerns about productivity and profitability. Notably, BR11, an MRV, stands out as a prominently adopted rice cultivar during the Aman rice-growing season. This study aims to assess the levels of essential nutrient minerals (Na, K, Ca and Mg) and potentially toxic elements (PTEs) (Cd, Cu, Pb, Ni, Co, Fe, Mn, Zn, Cr) in the BR11 rice cultivar and also to evaluate associated health risks. The concentrations of Na, K, Ca and Mg (mg 100 g–1) in the sampled BR11 rice cultivar were found to be 4.4 ± 2.4, 108.5 ± 24.9, 3.4 ± 0.4 and 4.5 ± 1.1, respectively. Among the PTEs, Cd, Pb, Ni, Co, or Cr contents were below the detection limit, while Fe, Mn, Zn and Cu contents (mg kg–1) were 12.0 ± 4.0, 9.2 ± 1.5, 18.7 ± 2.7 and 2.9 ± 1.0. Comparisons of PTE contents in BR11 rice cultivars exposed to industrial activities with those cultivated in non-industrial zones did not reveal any statistically significant variations (p < 0.05). The estimated daily intake of nutrient minerals through the consumption of BR11 rice was significantly below the daily recommended dietary reference intakes. Likewise, the accumulation of PTEs in the BR11 rice cultivar was well below the maximum allowable concentrations recommended by WHO or FAO. Health risk assessments, involving the computation of non-carcinogenic and carcinogenic risks, did not indicate any concerning risk scenarios associated with the consumption of the BR11 rice cultivar. The data suggests that BR11 is a safe MRV for daily consumption, affirming its suitability for inclusion in the daily diet.