Makhmetova A.T.

Karaganda State University named after acad. E.A. Buketov

Microelement status of teenager children of an industrial city

Abstract: During the research a cohort-blind study of the trace substance composition of the blood of teenagers aged 14-16 years, living in an industrial town, where for a long period large industrial enterprises of ferrous and nonferrous metallurgy were operating was conducted. The lack of the vital blood element selenium, which causes an accumulation of toxic metals cadmium and mercury, was determined.

Keywords: teenagers, microelements, imbalance, toxic metals.

Throughout the life cycle, from inception until his death, the human body undergoes a series of consecutive and regular morphological, biochemical, and physiological (functional) changes. The adverse impact of anthropogenic factors on human health is the most noticeable in the industrial centers. The problem of the imbalance of trace elements in the human body affects the fundamental biochemical mechanisms, with which the essential and toxic elements affect the metabolism. Trace elements are an integral part of many proteins and are involved in important biochemical processes, in particular, perform basic functions in a free-radical oxidation, the oxidation-reduction reactions, tissue respiration [1]. Imbalance of the chemical elements in the human body serves as a starting point, or contributes to the development of pathology, however at the same time, the absence of clinical manifestations of disease in children does not exclude the presence of prenosological and functional impairments [2]. Changes associated with puberty in adolescence, are among the most significant, because in this period, the morphological differentiation of tissues, organs and systems proceeds. It is recognized that the growing organism that resides under the constant influence of anthropogenic factors sensitively responds to these influences [3, 4].

Given the significant increase in functional disorders of body systems among adolescent children related to adverse environmental conditions, the objective of this study was to examine trace element composition of the blood in healthy adolescents during puberty period, who live in an industrial town.

Materials and methods: The cohort-blind study of trace-element composition of the blood of adolescent children aged 14-16 years living in the industrial city was conducted. The examination of children was conducted of children with written permission of their parents. For the control group were selected adolescent children living in ecologically favorable region. For examination organized children were selected, who attend educational institutions- schools that meet hygiene requirements. Based on a specially designed questionnaire qualitatively similar group of teenagers were formed. At the time of the examination all the teenagers were healthy, did not have acute respiratory diseases, chronic pathologies.

To examine the trace element composition of the blood, the blood sampling from the cubital vein was taken into vacutainers with sodium citrate. Examination of blood on the content of elements was carried out on atomic absorption spectrometer MGA - 915 [5, 6]. Fundamental methodologies used during this examination were the statistical methods and evaluation criteria. To identify significance of differences and relation of the prevalence in the groups the values of the relative risk (OR) and index xi-square (χ²) were used. Statistically significant differences between groups were calculated using the Mann Whitney nonparametric method for two unrelated groups. The results were processed using the STATISTICA 5.5 software package [7].

Results and discussions: Changes in the elemental status allow defining a group of metabolic disorders in certain nosological forms. The informational content of multi-element analysis was proved in solving problems associated with an increased frequency of cancer, cardiovascular, neuro-psychiatric and metabolic diseases in specific biogeochemical regions and for different professional, social and age groups, including children [8,9,10] .

Comparative analysis of trace-element composition of the blood of adolescent- children showed that the content of toxic elements - mercury, cadmium, is significantly higher, however, the decreased content of a vital element – selenium was noticed in the adolescent children who live in the industrial region (Table 1).

Table 1
Trace element composition of the blood of adolescent children living in the industrial city

Element	Control group (n=110)	Confidence interval	Industrial city (n=111)	Confidence interval
Mercury	0,32±0,06	0,2-0,43	1,77±0,19*	1,38-2,17
Lead	3,28±0,15	2,98-3,58	4,0±0,2	3,61-4,4
Cadmium	0,2±0,19	0,15-0,26	0,63±0,06*	0,52-0,74
Copper	79,8±0,75	78,2-81,3	85,5±1,1	83,3-87,7
Zinc	115,1±0,8	113,5-116,7	116,5±2,6	111,4-121,6
Selenium	138,2±23,2	90,5-185,9	54,8±2,5*	49,8-59,8
Note: * - significant difference when р<0,01

The relative risk of mercury and cadmium amount increase, as well as reduction of the amount of selenium in the blood of adolescent children in the industrial region is higher than in the children living in an ecologically clean region is noted. Significance of the result is confirmed with the values χ2 = 4,23 for mercury, χ2 = 8,97 for cadmium, χ2 = 16,63 for selenium(Table 2).

Table 2
The relative risk of mercury, cadmium and selenium amount breach in the blood of adolescent children: industrial city - an environmentally clean region

Parameter	The lower limit of confidence interval	The upper limit of confidence interval	Relative risk	χ^2	The etiological fraction
Mercury	1,0	18,19	6,48	4,23	84,58
Cadmium	1,7	11,93	2,61	8,97	61,72
Selenium	3,11	114,4	13,78	16,63	92,7

Thus, the results of trace-element composition of the blood of adolescent children who live in industrial city indicates the low content of the essential element - selenium, which in turn provokes the accumulation of toxic metals - mercury and cadmium[11].

In adolescent children the carrier state of toxic elements is observed, which is more dangerous for the growing young organism, as it is in this period when a functional body system is formed. In the future, such a carrier state may have a negative effect on fertility, metabolic processes, and the formation of the immune system. These results demonstrates the need for a comprehensive medical-biological, clinical-functional study of the exposed population.

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