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Objective:To explore the relationship between children's intelligence and urinary fluoride in Suojia Township of Miao, Yi and Hui Nationalities (referred to as Suojia Township), a coal-burning-borne endemic fluorosis area in Guizhou Province.Methods:In April 2019, 173 children aged 10 to 13 years old were selected from three schools in Suojia Township. According to whether they had dental fluorosis, the children were divided into case group ( n = 104) and control group ( n = 69). Middle segment urine samples of the children were collected and urinary fluoride level was determined by the method of ion-selective electrode. Combined Raven's Test-the Rural in China (CRT-RC2) was used for children's intelligence quotient (IQ) test. Linear regression analysis was used to observe the association between urinary fluoride and IQ, and the results were expressed by regression coefficient ( β) and 95% confidence interval ( CI). Results:Urinary fluoride level of case group was higher than that of control group [(2.14 ± 1.78) vs (1.53 ± 0.98) mg/L], and IQ was lower than that of control group [(92.33 ± 11.68) vs (100.38 ± 11.87) points], and the differences were statistically significant ( t = 2.58, 4.41, P < 0.05). The linear regression equation of urinary fluoride ( X) and IQ ( Y) of case group was Y = 96.99 - 2.86 X. For every 1 mg/L increase in urinary fluoride level, IQ decreased by 2.86 points ( β = - 2.86, 95% CI: - 5.48 - - 0.24). Conclusion:Long-term exposure to fluoride pollution from coal burning may damage children's intelligence, and children's IQ decreases with increase of fluoride level in urine.
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Objective:To investigate the association between relative mitochondrial DNA copy number (mtDNA-CN) and coal-burning-borne endemic fluorosis (abbreviated as coal-burning-borne fluorosis).Methods:From June 2018 to March 2019, using cross-sectional study, 482 patients with coal-burning-borne fluorosis were selected as the case group in Bijie City, a typical coal-burning-borne fluorosis area of Guizhou Province; meanwhile, 212 healthy individuals from Changshun County, a non-coal-burning-borne fluorosis area in Guizhou Province, were selected as the control group. Questionnaire survey and physical examination were used to collect general condition such as basic information and living habits of the two groups, peripheral venous blood samples were collected, and real-time fluorescence quantitative PCR was used to detect the relative mtDNA-CN in peripheral blood. The correlation between relative mtDNA-CN and coal-burning-borne fluorosis was analyzed by binary and unordered multi-class logistic regression.Results:There were significant differences in the body mass index (BMI), and the distribution of gender rario, marital status and education level between the control group and the case group ( t = 7.91, χ 2 = 5.11, 13.33, 34.32, P < 0.05). The relative mtDNA-CN in the control group was higher than that in the case group [median (quartile): 202 (138, 292) vs 131 (96, 217), Z = - 7.80, P < 0.001]. The results of binary logistic regression analysis [odds ratio (95% confidence interval)] showed that educational level [primary school: 0.572 (0.377 - 0.868), junior high school and above: 0.292 (0.174 - 0.493)], relative mtDNA-CN [131 - < 217: 0.265 (0.144 - 0.488), ≥217: 0.183 (0.100 - 0.335)] and BMI [1.222 (1.142 - 1.307)] were the influencing factors for the risk of coal-burning-borne fluorosis( P < 0.05). In subgroups with different BMI and educational levels, the relative mtDNA-CN was significantly negatively correlated with the risk of coal-burning-borne fluorosis( Ptrend < 0.05), and there was no interaction between mtDNA-CN and BMI and educational levels ( Pinteraction > 0.05). The results of unordered multi-class logistic regression analysis showed that the relative mtDNA-CN were significantly negatively correlated with the risk of dental fluorosis and skeletal fluorosis ( Ptrend < 0.05). Conclusion:The higher the relative mtDNA-CN, the lower the risk of coal-burning-borne fluorosis, suggesting that mtDNA-CN may be a potential biomarker of coal-burning fluorosis.
ABSTRACT
Objective:To investigate the relationship between gene polymorphism of osteoprotegerin (OPG) and coal-burning endemic fluorosis in Guizhou Province.Methods:In 2018 and 2019, a case-control study was conducted in Bijie City, a typical coal-burning endemic fluorosis area in Guizhou Province, and 260 cases of coal-burning endemic fluorosis patients were selected as case group. According to the "Diagnostic Criteria for Endemic Skeletal Fluorosis" (WS 192-2008), the case group was divided into severe group (130 cases) and mild group (130 cases). At the same time, 130 cases without dental fluorosis and skeletal fluorosis symptoms were chosen as control group in Changshun County, a non-coal-burning endemic fluorosis area in Guizhou Province. Whole blood genomic DNA was extracted, and real-time fluorescence quantitative PCR with TaqMan-MGB probe was utilized to type the OPG gene rs2460985, rs2073618, rs6469804 and rs6993813 four single nucleotide polymorphism (SNP) loci of all samples, and genetic model analysis was performed to compare the frequency distribution of its alleles, genotypes and constructed haplotypes in control, mild and severe groups. Results:By Hardy-Weinberg equilibrium test, the genotype frequencies of the four SNP loci all reached genetic balance in control, mild and severe groups ( P > 0.05). There was a statistically significant difference in the genotype frequency of OPG gene rs6469804 locus among the three groups (χ 2 = 10.615, P < 0.05), and the difference in the genotype frequency of this locus between the control group and the severe group was statistically significant (χ 2 = 6.784, P < 0.05). The results of genetic model analysis showed that in comparison between the control group and the severe group, the optimal genetic model of rs6469804 locus was the overdominant genetic model, the frequency distribution of genotypes AA + GG and AG in the control group and the severe group was statistically significant [odds ratio ( OR) = 1.94, 95% confidence interval ( CI): 1.16 - 3.23, P < 0.05], genotype AG was a risk factor for coal-burning endemic fluorosis. In comparison between the control group and the mild group, the optimal genetic model of rs2073618 locus was the recessive genetic model, the frequency distribution of genotypes GG + GC and CC in the control group and the mild group was statistically significant ( OR = 3.17, 95% CI: 1.08 - 9.30, P < 0.05), genotype CC was a risk factor for coal-burning endemic fluorosis. In comparison between the control group and the mild group, haplotypes C-C-G-T and T-G-A-C were risk factors for coal-burning endemic fluorosis (adjusted OR = 2.41, 1.98, 95% CI: 1.29 - 4.50, 1.22 - 3.23, P < 0.05); in comparison between the control group and the severe group, haplotype T-G-A-C was a risk factor for coal-burning endemic fluorosis (adjusted OR = 1.87, 95% CI: 1.14 - 3.07, P < 0.05). Conclusion:OPG gene rs6469804 locus genotype AG and rs2073618 locus genotype CC may be risk factors for coal-burning endemic fluorosis.