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ПОР1ВНЯЛЬНА ОЦ1НКА МЕТАБОЛ1ЧНИХ ПРОЦЕС1В У Д1ТЕЙ, ЯК1 ПРОЖИВАЮТЬ У РАЙОНАХ, ЩО ПОСТРАЖДАЛИ В1Д АВАР11 НА ЧОРНОБИЛЬСЬК1Й АЕС
Бандажевський Ю.1., Дубова Н.Ф.
COMPARATIVE ASSESSMENT OF METABOLIC PROCESSES IN CHILDREN LIVING IN THE AREAS AFFECTED BY THE CHERNOBYL NUCLEAR POWER PLANT ACCIDENT
1 BANDAZHEVSKYI Yu. I., ^ DUBOVA N.F.
1 Ecology and Health Coordination and Analytical Centre, Ivankiv 2 National P.L. Shupyk Medical Academy of Postgraduate Education, Kyiv
УДК 616-008.9-001.28-053.6/.7 : 613.2-06:613.956/.96: 612.015. 3/.6 : 614.876:621.039.004.6
Keywords: homocysteine, folate metabolism, thyroid and pituitary hormones, folic acid, vitamin B12, adolescents, radiation-contaminated areas.
he level of metabolic processes is one of the main markers of the health of the human body. It depends on the state of the genetic apparatus and the impact of external environment. It is important to determine the nature of the impact of external environment in areas affected by the Chornobyl nuclear power plant (CNPP) accident in order to organise effective preventive measures for radiation exposure related diseases. So, in our opinion, it is reasonable to carry out a comparative assessment of metabolic processes in the population living after the Chornobyl accident in various districts.
Purpose of the study: comparative assessment of metabolic processes in children continually living in Polissia and Ivankiv districts, Kyiv region, in the areas contaminated with radioactive elements as a result of the CNPP accident.
Material and methods. The study was carried out in Polissia and Ivankiv districts which territory is contaminated with radionuclides as a result of the CNPP accident (the 137Cs soil contamination density is <2 Curie/km2 [1]). The age of children at the time of
examination was (15.2 ± 0.9) years (95% CI 15.0-15.4 years).
Gamma-emitting radionuclide (134Cs and 137Cs) concentrations were measured in 176 children from Polissia district and 222 children from Ivankiv district using a three-detector whole-body counter manufactured by Atom Komplex Prylad (Ukraine).
158 children from Polesia district and 179 children from Ivankiv district were examined in 2015. For this purpose, levels of thyroid stimulating hormone (TSH), free triiodothyronine (T3), free thyroxine (T4), homocysteine (He), vitamins B9 and B12 in the blood and state of the genetic system of folate metabolism were assessed.
All children had blood drawn from the ulnar vein on an empty stomach in the morning to carry out above analyses. All of them at the time of blood draw attended school.
Blood samples were analysed in a laboratory certified under quality standards with the financial support of the Rh^ne-Alpes Regional Council (France) and the agreement of parents.
TSH, T3 and T4 concentrations
ПОР1ВНЯЛЬНА ОЦ1НКА МЕТАБОЛ1ЧНИХ ПРОЦЕС1В УД1ТЕИ, ЯК1ПРОЖИВАЮТЬ У РАЙОНАХ, ЩО ПОСТРАЖДАЛИ В1Д АВАРП НА ЧОРНОБИЛЬСЬКЙ АС 1 Бандажевський Ю.1., 2 Дубова Н.Ф.
1 Координашйний анал'тичний центр «Еколопя \ здоров'я». м. 1ванюв
2 Нац'юнальна медична академ'я пюлядипломно! освти iм. П.Л. Шупика. м. Кив
Мета — порiвняльна ошнка метабол'чних проце-св у дтей. як тривалий час проживають у Полському та 1ванквському районах Кшвсько! област на територп. забрудненй рад'юактивни-ми елементами внаслдок аварп на Чорнобильськй атомнй електростанцп. Матерал i методи дослдження. У п^тюв визначався вмст радонукл^в 137Сэ. ошнювався вмст у крови тиреотропного гормону гiпофiза. трийодтиронну. тироксину. гомоцистену. вта-мiнiв В9. В12, а також стан генетичноI системи фолатного циклу. Використовувалися '¡мунох'шч-ний i математико-статистичний методи. Результати роботи. Питома вага дтей дослд-жуваноI вковоI групи з концентращею 137Сэ в органiзмi вище 5 Бк/кг маси тла склав у Полiському^ район\ 34,1% \ був достовiрно вищим (р<0.05). нж в 1ванювськомурайон\ (14,4%). Геном фолатного циклу дгтей з обох район '1в не
мав ютотних вдмнностей. Алел'1 ризику генетич-них полiморфiзмiв фолатного циклу були вдсутнi-ми у 3,2% випадюв у дтей з Полюького району i в 1,1% випадюв — у дтей з 1ванювського району. Рiвень гомоцистену перевищував ф^зюлопчний критерй (стан ппергомоцисте'шемп) у дтей з Полюького району у 79,8% випадюв, у дтей з 1ванювського району — у 73,2% випадюв. Удтей з Полюького району вмют фолieвоï кислоти i тироксину у крови був вiрогiдно меншим, нж у дтей з 1ванювського району.
Висновки. Причинами пдвищеного вмсту радонукп^в в органiзмi, ппергомоцисте'/'немп, порушення продукцп гормонiв щитопо^бно)' залози, дефциту фолieвоï кислоти i втамну В12 у дтей Полського району порiвняно з дтьми 1ванювського е незадовiльнi сощально-економ'ч-нi умови проживання. 1нкорпоращя радонукл^в 137Cs в органiзм i щитоподбну залозу, дефiцит фолiевоï кислоти можуть призводити до порушення продукцп тироксину щитоподбноï зало-зою у дтей, як проживають на територп, забрудненй рад 'юнукл'1дами внаслдок аварп на Чорнобильськй атомнй електростанцп.
Ключовi слова: гомоцисте)'н, фолатний цикл, гормони щитопод'бно)' залози i ппоф'1за, фол'ева кислота, в'пам'ш B12, п^тки, радiацiйно забруднен райони.
© Бандажевський Ю.1., Дубова Н.Ф. СТАТТЯ, 2017.
27 Environment & Health №42017
were determined using the immunochemical method with electrochemiluminescent detection (ECLIA), an analyser and a test systems: Cobas 6000; Roche Diagnostics (Switzerland).
Blood homocysteine levels were determined using an immunochemical method with chemiluminescent detection (CLIA). An analyser and a test system: Architect 1000 (ABBOT Diagnostics (USA). Blood homocysteine levels of over 10 pmol/L in the children were defined as hyperhomocysteinemia.
Vitamin B9 (folacin) concentrations were determined using the immunochemical method with electrochemiluminescent detection (ECLIA). An analyser and a test system: Cobas e411; Roche Diagnostics (Switzerland).
Vitamin B12 (holotranscobal-amin, active vitamin B12) concentrations were determined using the immunochemical method
with chemiluminescent detection (CLIA). An analyser and a test system: Architect 1000 (Abbott Diagnostics (USA).
The allelic variants C677T and A1298C of the MTHFR gene (synthesis of the methylenetetrahy-drofolate reductase enzyme), A2756G of the MTR gene (synthesis of the B12-dependent methio-nine synthase enzyme) and A66G of the MTRR gene (synthesis of the methionine synthase reduc-tase enzyme) were determined during genetic analysis of folate metabolism.
A real-time PCR method was used. An analyser and a test system: DT-96 detecting thermocy-cler, DNA-Technology (Russia).
The statistical processing of the obtained results was performed using the IBM SPSS Statistics 22 software (USA). The arithmetic mean (M) ± standard error of mean (m), confidence interval for the average value (95% CI),
Table 1
Percentage of cases that include risk alleles of folate metabolism genetic polymorphisms in the groups of examined children
Subgroup № Number of polymorphisms Polissia district Ivankiv district
Absolute number Percentage, % Absolute number Percentage, %
1 0 5 3.2 2 1.1
2 1 32 20.2 25 14.0
3 2 66 41.8 85 47.5
4 3 49 31.0 52 29.0
5 4 6 3.8 15 8.4
Total 158 100 179 100
Table 2
Percentage of polymorphic alleles of folate metabolism genes in the children from Polissia district, (n=158)
Gene, polymorphism "Neutral" allele "Heterozygous genotype" risk allele "Homozygous genotype" risk allele
Absolute number % Absolute number % Absolute number %
MTR:A2756G 104 65.8 45 28.5 9 5.7
MTHFR:A1298C 82 51.9 60 38.0 16 10.1
MTHFR:C677T 79 50.0 60 38.0 19 12.0
MTRR:A66G 32 20.2 72 45.6 54 34.2
Table 3 Percentage of polymorphic alleles of folate metabolism genes in the children from Ivankiv district, (n=179)
Gene, polymorphism "Neutral" allele "Heterozygous genotype" risk allele "Homozygous genotype" risk allele
Absolute number % Absolute number % Absolute number %
MTR:A2756G 106 59.2 62 34.6 11 6.2
MTHFR:A1298C 90 50.3 80 44.7 9 5.0
MTHFR:C677T 81 45.2 83 46.4 15 8.4
MTRR:A66G 27 15.1 94 52.5 58 32.4
median (Me), interquartile range (IR), minimum and maximum parameter values and percentiles were calculated for the variables under analysis. The distribution hypothesis was tested (a Kolmogorov-Smirnov test). All the parameters under study did not conform to the normal distribution law, thus, a non-parametric U Mann-Whitney test was used to compare values. The statistical significance of variables was assessed by determining a significance level for p with the help of a statistical software programme. The Student's t-test was used to compare relative values. The critical level of significance for the null hypothesis (p) was set at 0.05. The relationship between blood thyroxin, folic acid and vitamin B12 levels was established with the help of the Spearman's rank correlation coefficient (rxy). Strength of correlation was assessed by a typical scale: weak - 0 to 0.299; moderate - 0.3 to 0.699; strong - 0.7 to 1.0.
Results and discussion. The percentage of children of the age group under study with 137Cs levels of over 5 Bq/kg of body weight was 34.1% in Polissia district (60 cases out of 176) and was significantly higher (p<0.05) than in Ivankiv district - 14.4% (32 cases out of 222).
There were no differences between the groups of children from Polissia and Ivankiv districts in terms of the percentage of cases that include risk alleles of folate metabolism genetic polymorphisms. The absence of risk alleles of folate metabolism genetic polymorphisms was detected in 3.2% of the children from Polissia district and in 1.1 % of the children from Ivankiv district. The highest percentage was held by the subgroups with two polymorphisms (table 1).
There were no differences between the groups of children from Polissia and Ivankiv districts in terms of the percentage of polymorphic alleles of folate metabolism genes (tables 2-3). In the both groups of children, the proportion of cases with a genotype that includes only a neutral allele for the MTR:A2756G and MTHFR:A1298C polymorphisms exceeded the proportion of cases with genotypes that include a risk allele. In the case of the MTHFR:C677T and MTRR:A66G polymorphisms, the proportion of cases with a risk allele was over or
№ 4 2017 Environment & Health 28
COMPARATIVE ASSESSMENT OF METABOLIC PROCESSES IN CHILDREN LIVING IN THE AREAS AFFECTED BY THE CHORNOBYL NUCLEAR POWER PLANT ACCIDENT 1 Bandazhevskyi Yu.I., 2 Dubova N.F.
1 Ecology and Health Coordination and Analytical Centre, Ivankiv, Ukraine
2 National P.L. Shupyk Medical Academy of Postgraduate Education, Kyiv
Objective. We performed a comparative assessment of metabolic processes in the children living for a long time in Polissia and Ivankiv districts of Kyiv oblast, at the territories contaminated with radioactive elements as a result of the accident at the Chornobyl NPP.
Materials and methods. We determined a content of 137Cs radionuclides, a content of thyrotropic pituitary hormones, triiodothyronine, thyroxin, homocysteine, vitamins B9, B12 in the blood of the adolescents, and a state of folate metabolism genetic system as well.The immunochemical and mathemati-cal-and-statistical methods were applied. Results. The percentage of the children in the age group under study with 137Cs concentration in the organism over 5 Bq/kg of body weight was 34.1% in Polissia district and was significantly higher (p<0.05) than in Ivankiv district - 14.4%. The genome of folate metabolism didn't have significant
differences in the children of both districts. There were no risk alleles of folate metabolism genetic polymorphisms in 3.2% of the cases in the group of the children from Polissia district and in 1.1% in the group of the children from Ivankiv district. A level of homocystenia exceeded a physiological criterion (state of hyperhomocysteinemia) in 79.8% of cases in the group of the children from Polissia district and in 73.2% of cases in the group of the children from Ivankiv district. A content of folic acid and thyroxine in the blood was significantly lower in the group of children from Polissia district than in Ivankiv district. Conclusions. The poor socio-economic conditions are the reasons for a higher content of radionu-clides, hyperhomocysteinemia, disruption of the production of thyroid gland hormones, deficiency of folic acid and vitamin B12 in the children from Polissia district in comparison with the children from Ivankiv district. The incorporation of 137Cs radionuclides in the organism and thyroid gland, and folic acid deficiency can lead to disruption of thyroxine production by the thyroid gland in the children living at the territory contaminated with radionuclides as a result of the accident at the Chornobyl NPP.
Keywords: homocysteine, folate metabolism, thyroid and pituitary hormones, folic acid, vitamin B12, adolescents, radiation-contaminated areas.
of the children from Polissia district was 2.14-13.23 ng/ml and 2.34-15.89 ng/ml for the children from Ivankiv district.
The percentage of cases with folic acid and thyroxine levels below the reference values was significantly lower in the group of children from Ivankiv district than
equal to the proportion of cases with a neutral allele. The proportion of cases with heterozygous variants that include a risk allele exceeded the proportion of cases with homozygous variants with the same allele.
Hyperhomocysteinemia was observed in 79.8% of cases (67 out of 84 cases) in the group of children from Polissia district and in 73.2% of cases (131 out of 179 cases) in the group of children from Ivankiv district.
The comparative analysis did not reveal any statistically significant differences between blood homocysteine (Hc) values in the children from the both districts. At the same time, it was established that blood vitamin B9, triiodothyronine and thyroxine levels were significantly higher in the group of children from Ivankiv district than in the group of children from Polissia district (tables 4-5).
The reference range for folic acid (vitamin B9) in the blood specified by the laboratory where the analysis was done was 4.618.7 ng/ml, for vitamin B12 -191.0-663.0 pg/ml.
The interval between the extreme values of vitamin B12 in the blood of the children from Polissia district was 160.9-902.5 pg/ml and 136.1-853.4 pg/ml for the children from Ivankiv district. The interval between the extreme values of vitamin B9 in the blood Note: 1 - group 1; 2 - group 2.
29 Environment & Health №42017
in the group of children from Polissia district (table 6).
A direct weak correlation was established between thyroxine and folic acid levels (rxy=0.166, p=0.026, n=179), and between thyroxine and vitamin B12 levels (rxy=0.230, p<0.02, n=179) in the group of children from Ivankov district.
Table 4
Statistical characteristics of blood variables of metabolic processes in the children examined
Variables Polissia district Ivankiv district
Me IR Me IR
HC, mMOL/L 12.25 10.43-14.48 11.61 9.69-13.35
B9, NG/ML 5.43 4.34-6.92 6.53 5.10-7.95
B12, PG/ML 318.65 256.53-437.13 309.10 255.10-422.40
TSH, MIU/ML 1.86 1.41-2.48 1.80 1.30-2.40
T3, PG/ML 4.1 3.79-4.62 4.40 3.99-4.75
T4, NG/DL 1.18 1.07-1.28 1.23 1.14-1.31
Table 5
Results of statistically significant differences when comparing blood variables of metabolic processes in the examined children from Polissia1 and Ivankiv2 districts
Variables Groups of comparison Comparison group size Average rank U test value, Significance level, p
Bg, ng/ml 1 84 109.76 U = 5650.0;
2 179 142.44 p = 0.001
T3, pg/ml 1 158 150.69 U = 11247.5;
2 179 185.16 p = 0.001
T4, ng/dl 1 158 152.88 U = 11594.5;
2 179 183.23 p = 0.004
Thus, during the studies conducted it was found that a significantly larger number of children from Polissia district in comparison with Ivankiv district had 137Cs levels of over 5 Bq/kg of body weight. The main reason for this may be the consumption by the children of food products of local production, mushrooms, forest berries and the meat of wild animals containing radioactive elements.
No differences were found in terms of the genome of folate metabolism in the children from the districts under study. However, the genome of the children examined contained risk alleles. Only 3.2% of the children from Polissia district and 1.1% of the children from Ivankiv district had no risk alleles of folate metabolism genetic polymorphisms.
Homocysteine levels exceeded the physiological range in more than 70.0% of the children from both groups. An inverse association was observed between blood homocysteine and B9 and B12 levels in the children living in the areas affected by the Chornobyl accident [2].
A folic acid deficiency is more pronounced in the children from Polissia district comparing to the children from Ivankiv district. First of all, it is associated with an alimentary factor.
The associations between thy-roxine and folic acid levels, and thyroxine and vitamin B12 levels suggest that a folate and vitamin B12 deficiency may be the reason for inadequate thyroxine production by the thyroid gland.
Considering that the thyroid gland intensively incorporates 137Cs radionuclides [3], one can say that the latter participate in the disruption of thyroxine production.
Percentage of cases with values
Thus, the main differences between the children from Polissia and Ivankiv districts are associated with blood folic acid and thyroxine levels.
The children from Polissia district are in conditions of a more pronounced folic acid deficiency in comparison with the children from Ivankiv district located closer to Kyiv. The reason for this, first of all, is a poor socio-economic situation in Polissia district [4]. As a result, its inhabitants resort to consuming wild mushrooms and berries and meat of local wild animals containing large doses of radionuclides. Radiation exposure and folic acid deficiency result in abnormal thyroid function and decreased thy-roxine production.
Conclusions
1. There was a considerably larger percentage of cases with body 137Cs levels of over 5 Bq/kg in the group of children from Polissia district than in the group of children from Ivankiv district, though the both districts had 137Cs soil contamination levels of <2 Cu/km2.
2. The genome of folate metabolism of the children from the both districts had no significant differences. The risk alleles of folate metabolism genetic polymorphisms were absent in 3.2% of cases in the group of children from Polissiaidistrict and in 1.1% of cases in the group of children from Ivankiv district.
3. Homocysteine levels exceeded the physiological range (hyperhomocysteinemia) in 79.8% of cases in the group of children from Polissia district and in 73.2% of cases in the group of children from Ivankiv district.
4. Blood folic acid and thyroxine levels were significantly lower
Table 6
different from the reference ones
Variables Polissia district Ivankiv district
N1 Number of cases % N Number of cases %
Hc, pmol/L 84 67 79.8 179 131 73.2
Bg, ng/ml 84 25 29.8 179 29 16.2*
B12, pg/ml 84 4 4.8 179 9 5.0
TSH, MIU/mL 158 4 2.5 179 4 2.2
Т3, pg/ml 158 18 11.4 179 26 14.5
Т4, ng/dl 158 49 31.0 179 35 19.6*
Note: * — statistical differences between groups (p<0.05); ** — values below the reference values were taken into account when assessing B9, B12, T4, above the reference values — when assessing Hc, TSH, T3; N1 — group size.
in the children from Polissia district than in the children from Ivankiv district.
5. The poor socio-economic conditions are one of the main reasons for inadequate intake of folic acid in the children from Polissia district. The incorporation of 137Cs radionuclides into the body and thyroid gland, and folic acid deficiency can lead to disruption of thyroxine production by the thyroid gland in children living in the areas contaminated with radionuclides as a result of the CNPP accident.
Л1ТЕРАТУРА
1. Загальнодозиметрична пас-портизащя та результати ЛВЛ-мошторингу у населених пунктах Укра'ши, яю зазнали радюактив-ного забруднення тсля Чорнобильсько''' катастрофи. Даш за 2011 р. ЗБ1РКА 14. МОЗ Укра'ши, НАМНУ Укра'ши, МНС Укра'ши, ДАЗВ, ДУ "ННЦРМ НАМН Укра'ши", НД 1РЗ АТН Укра'ши. Ки'в, 2012. 99 с.
2. Бандажевский Ю.И., Дубовая Н.Ф. Гипергомоцистеинемия и В12-фолиевый дефицит у детей, проживающих на территории, загрязненной радионуклидами в результате аварии на Чернобыльской атомной электростанции. Педиатрия. Восточная Европа. 2017. Т. 5. №1.С. 25-32.
3. Bandazhevskyi Yu.I. Cs-137 incorporation in children's organs. Swiss. Med. Weekly. 2003. Vol. 133. Р. 488-490.
4. Лiбанова Е.М. Чорнобильська катастрофа: 25 роюв потому. Демограф'я та соцальна еконо-мка. 2011. № 2 (16). С. 3-18.
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Надiйшла до редакцИ 15.06.2017
№ 4 2017 Environment & Health 30
