The complex relationship between trace elements and skeletal health has received increasing attention in the scientific community. Among these minerals, manganese (Mn) has emerged as a key element affecting bone metabolism and integrity. This review examines the multifaceted role of Mn in bone health, including its effects on bone regeneration, mineralization, and overall skeletal strength. This review article is based on a synthesis of experimental models, epidemiologic studies, and clinical trials of the mechanisms of the effect of Mn on bone metabolism. Current research data show that Mn is actively involved in the processes of bone remodeling by modulating the activity of osteoblasts and osteoclasts, as well as the main cells that regulate bone formation and resorption. Mn ions have a profound effect on bone mineralization and density by intricately regulating signaling pathways and enzymatic reactions in these cells. Additionally, Mn superoxide dismutase (MnSOD), located in bone mitochondria, plays a crucial role in osteoclast differentiation and function, protecting osteoclasts from oxidative damage. Understanding the nuances of Mn’s interaction with bone is essential for optimizing bone strategies, potentially preventing and managing skeletal diseases. Key findings include the stimulation of osteoblast proliferation and differentiation, the inhibition of osteoclastogenesis, and the preservation of bone mass through the RANK/RANKL/OPG pathway. These results underscore the importance of Mn in maintaining bone health and highlight the need for further research into its therapeutic potential.

Selenium (Se) is a vital trace element for children, playing a crucial role in numerous physiological processes, including antioxidant defense, immune regulation, thyroid function, and bone metabolism. Emerging evidence highlights its potential impact on child development and growth while also underscoring the complexity of its mechanisms and the global variations in Se intake. The aim of this review is to comprehensively elucidate the significance of Se in various biological processes within the human body, with a focus on its role in child development and growth; its biochemical effects on the nervous system, thyroid function, immune system, and bone tissue; and the implications of Se deficiency and toxicity. This review integrates findings from experimental models, epidemiological studies, and clinical trials to explore Se’s role in neurodevelopment, growth regulation, and immune competence in children. Selenoproteins, which regulate oxidative stress and thyroid hormone and bone metabolism, are essential for normal growth and cognitive development in children. Se deficiency and toxicity has been linked to impaired immune function, growth retardation, and decreased immune function. The findings underscore Se’s influence on various biological pathways that are critical for healthy child development and its broader importance for child health. Public health strategies aimed at optimizing selenium intake may play a pivotal role in improving pediatric health outcomes worldwide.

Most of the country’s oil and gas fields are situated in West Kazakhstan, mainly on the Caspian Sea coast, causing significant damage to the local environment and contributing to an imbalance in the trace element composition of the human body. The study is aimed to evaluate the relationship between the concentration of essential trace elements in scalp hair of the western Kazakhstan adult population and the remoteness of their residence from oil and gas fields. The concentration of essential trace elements (Co, Cu, Fe, I, Mn, Se, Zn) in the hair of 850 individuals aged 18–60 years was determined by inductively coupled plasma mass spectrometry. In residents of settlements located at a distance of >110 km from oil and gas fields, the concentration of Cu and I in hair was significantly higher than in those closer to 110 km (p < 0.001). The content of Cu and I were associated with the distance to oil and gas fields (0.072 (95% CI: 0.050; 0.094)) and (0.121 (95% CI: 0.058; 0.185)), respectively. We detected a significant imbalance in the distribution of some essential trace elements in residents’ scalp hair from the Caspian region of western Kazakhstan, living near oil and gas fields. The concentrations of Cu and I were significantly interrelated with the distance to oil and gas fields. The level of copper in the hair of both inhabitants of the area most remote from oil and gas facilities and the entire population of western Kazakhstan as a whole remains significantly low. The data obtained provide evidence of the possible impact of pollutants generated by the oil and gas facilities on a shortage of essential trace elements and associated subsequent health risks.

Introduction: Western Kazakhstan is a heavily industrialized part of the country with developed oil- and gas industry, mining, nonfer-rous- and ferrous metallurgy. The region is also a boron-chromium geochemical province. Climate change contributes to shifts in the microelement balance of the biosphere leading to changes in the microelement status of the population affecting its health and well-being. Aim: To study the microelement status of adult population in industrialized areas of Aktobe and West Kazakhstan regions. Methods: Hair concentrations of Al, As, B, Be, Cd, Co, Cr, Cu, Fe, Hg, I, Li, Mn, Ni, Pb, Se, Si, Sn, V, Zn were assessed in218 men and 391 women with the average age of 44 years living in Aktobe and West-Kazakhstan regions. Hair samples were analyzed using inductively coupled plasma mass spectrometry. The presence of an elemental imbalance was established by comparing it with the Russian reference values. Results: Concentrations of trace elements (P2.5; P97.5) Mg/gin men were: Al (1,77; 31,18); As (0,016; 0,126); В (0,812; 7,51); Ве (0,000; 0,003); Cd (0,004; 0,239); Co (0,003; 0,166); Cr (0,175; 1,60); Cu (7,67; 17,36); Fe (9,46; 138,16); Hg (0,029; 1,20); I (0,123; 18,79); Li (0,016; 0,607); Mn (0,193; 7,47); Ni (0,062; 1,23); Pb (0,080; 5,49); Se (0,301; 0,797); Si (7,82; 64,68); Sn (0,013; 0,393), V (0,006; 0,111); Zn (88,25; 363,02).Corresponding values for women were: Al (0,855; 10,42); As (0,002; 0,070); В (0,241; 2,85); Ве (0,000; 0,002); Cd (0,001; 0,113); Co (0,002; 0,644); Cr (0,121; 1,52); Cu (4,97; 25,31); Fe (9,00; 61,81); Hg (0,025; 0,764); I (0,120; 4,80); Li (0,004; 0,173); Mn (0,125; 16,90); Ni (0,046; 1,09); Pb (0,032; 1,05); Se (0,183; 0,768); Si (6,20; 52,28); Sn (0,010; 1,73); V (0,006; 0,092); Zn (79,41; 639,07). The most significant differences were found in the content of toxic and potentially toxic elements with an excess in men of Al by 72.8 %, As by 59 %, Be by 98 %, Cd by 63 %, Pb by 62.3 %, and essential and conditionally - essential: Li by 41 %, Mn by 30.4 %, V by 67 %. Conclusions: In total, 99.5 % and 93.9 % of the adults from the industrialized areas of Western Kazakhstan have V and Se deficiency while 79.8 % have an excess of Li and 65.1 % had an imbalance in Zn.

Cobalt is a crucial trace element for the human body. It serves as an essentialcomponent of vitamin B12 and plays a pivotal role in the synthesis of amino acids andselect proteins within nerve cells, as well as in the synthesis of neurotransmitters vitalfor the proper functioning of the body. Both excess and deficiency of cobalt can havedetrimental effects on the human body. Notwithstanding the paramount significanceof cobalt as a trace element, comprehensive studies are necessary to evaluate its rolein physiological processes. Keywords: cobalt, human health, trace element, vitamin B12, physiological processes

This study aimed to assess the relationship between the content of toxic trace elements, such as aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), mercury (Hg), and lead (Pb), in the hair of the adult population of western Kazakhstan and the distance of their residence from oil and gas fields. The cross-sectional study included 850 adults aged 18–60 years. Inductively coupled plasma mass spectrometry was used to measure the level of Al, As, Be, Cd, Hg, and Pb in hair. The relationship between the concentration of toxic trace elements in the hair and the distance from oil and gas fields was assessed in three groups (110 km), using multiple linear regression analysis. The highest concentration of Hg = 0.338 μg/g was determined in the group living near oil and gas fields (0–16 km), whereas the lowest concentration of Al = 3.127 μg/g and As = 0.028 μg/g was determined in participants living at a long distance (more than 110 km) (p < 0.001). The concentration of Al (−0.126 (CI: −0.174; −0.077)), Hg (−0.065 (CI: −0.129; −0.001)), and Pb (0.111 (CI: 0.045; 0.177)) is associated with the distance to oil and gas fields. The obtained data indicate a change in the toxic trace element content in the hair of residents in the Caspian region of western Kazakhstan, a change that is most pronounced in residents living in the zone of oil and gas pollution. The distance to the oil and gas fields affects the content of toxic elements in scalp hair. In particular, the concentration of Al and Hg is associated with a decrease in the distance to oil and gas fields, while the concentration of Pb is associated with an increase in the distance to these fields. The lowest content of Al and As was determined in the hair of study participants living in the most remote areas (more than 110 km from oil and gas fields). Our results demonstrate the need for the biomonitoring of toxic elements to determine long-term temporal trends in the impact of chemicals on public health in western Kazakhstan.