Coal-burning Endemic Fluorosis Research Articles

Aberrant gut microbiota and fecal metabolites in patients with coal-burning endemic fluorosis in Guizhou, China.

Chronic exposure to excessive environmental fluoride has caused fluorosis to become a major public health problem worldwide. Although studies on stress pathways, signaling pathways, and apoptosis induced by fluoride have provided an in-depth understanding of the mechanism of this disease, its exact pathogenesis remains unclear. We hypothesized that the human gut microbiota and metabolome are associated with the pathogenesis of this disease. To get further insight into the profiles of intestinal microbiota and metabolome in coal-burning-induced endemic fluorosis patients, we conducted 16S rRNA sequencing of the intestinal microbial DNA and carried out non-targeted metabolomics of fecal samples from 32 patients with skeletal fluorosis and 33 matched healthy controls in Guizhou, China. We found that the gut microbiota of coal-burning endemic fluorosis patients displayed significant differences in composition, diversity, and abundance compared with healthy controls. This was characterized by an increase in the relative abundance of Verrucomicrobiota, Desulfobacterota, Nitrospirota, Crenarchaeota, Chloroflexi, Myxococcota, Acidobacteriota, Proteobacteria, and unidentified_Bacteria, and a significant decrease in the relative abundance of Firmicutes and Bacteroidetes at the phylum level. Additionally, at the genus level, the relative abundance of some beneficial bacteria, such as Bacteroides, Megamonas, Bifidobacterium, and Faecalibacterium, was significantly reduced. We also demonstrated that, at the genus level, some gut microbial markers, including Anaeromyxobacter, MND1, oc32, Haliangium, and Adurb.Bin063_1, showed potential for identifying coal-burning endemic fluorosis. Moreover, non-targeted metabolomics and correlation analysis revealed the changes in the metabolome, particularlythe gut microbiota-derived tryptophan metabolites such as tryptamine, 5-hydroxyindoleacetic acid, and indoleacetaldehyde. Our results indicated that excessive fluoride might cause xenobiotic-mediated dysbiosis of human gut microbiota and metabolic disorders. These findings suggest that the alterations in gut microbiota and metabolome play vital roles in regulating disease susceptibility and multi-organ damage after excessive fluoride exposure.

Analysis of the microRNA Profile of Coal-Burning Endemic Fluorosis Using Deep Sequencing and Bioinformatic Approaches.

MicroRNAs (miRNAs) differentially expressed in plasma were identified using microRNA sequencing (miRNA-seq), and five miRNAs were selected for validation. Potential target genes of these five miRNAs were predicted using the miRWalk3.0 database, and the overlapping portions were analyzed using the Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Comparison of the cases and controls revealed 127 known differentially expressed miRNAs. A total of 44 and 83 miRNAs were upregulated and downregulated, respectively. Through target gene prediction of five miRNAs, we obtained 1360 target genes. GO enrichment analysis showed that the target genes of these dysregulated miRNAs were related with secretion, protein binding, and cell growth. The KEGG pathway analysis showed that pathways in cancer, calcium signaling, and rat sarcoma (Ras) signaling, etc. were likely regulated by these five miRNAs. These findings highlight the distinct expression patterns of miRNAs in coal-burning endemic fluorosis.

Evaluation of acidity in late Permian outcrop coals and its association with endemic fluorosis in the border area of Yunnan, Guizhou, and Sichuan in China.

The junction area of Yunnan, Guizhou, and Sichuan provinces is the heaviest coal-burning endemic fluorosis zones in China. To better understand the pathogenicity of endemic fluorosis in this area, 87 coal samples from the late Permian outcrop or semi-outcrop coal seams were collected in eight counties of the junction area of Yunnan, Guizhou, and Sichuan provinces. The total fluorine and sulfate content, etc. in the coal was determined using combustion-hydrolysis/fluoride-ion-selective electrode method and ion chromatography, respectively. The results show that the total fluorine concentrations in the samples ranged from 44 to 382µgg-1, with an average of 127µgg-1. The average pH of the coals is 5.03 (1.86-8.62), and the sulfate content varied from 249 to 64,706µgg-1 (average 7127µgg-1). In addition, the coals were medium- and high-sulfur coals, with sulfur mass fraction ranging from 0.08 to 13.41%. By heating the outcrop coals, HF release from the coal was verified quantitatively without exception, while simulated combustion directly confirmed the release of sulfuric acid (H2SO4). The acid in coal may be in the form of acidic sulfate ([Formula: see text]/H2SO4) because of a positive relationship between pH and [Formula: see text] in the acidic coal. The possible reaction mechanism would be that a chemical reaction between the acid (H2SO4 or [Formula: see text]) and fluorine in the coal occurred, thereby producing hydrogen fluoride (HF), which would be the chemical form of fluorine released from coal under relatively mild conditions. The unique chemical and physical property of HF may bring new insight into the pathogenic mechanism of coal-burning endemic fluorosis. The phenomenon of coal-burning fluorosis is not limited to the study area, but is common in southwest China and elsewhere. Further investigation is needed to determine whether other endemic fluorosis areas are affected by this phenomenon.

Sources, distributions of fluoride in waters and its influencing factors from an endemic fluorosis region in central Guizhou, China

The use of high fluoride-content coal caused the severe coal-burning endemic fluorosis in Zhijin County, Guizhou Province, China. The long-term mine exploitation in this region is as an important source of acid mine drainage (AMD) and leads to the release of potential fluoride (F−) into the surrounding waters. Aiming to investigate the source, hydrogeochemical characteristics and influencing factors of fluoride in waters of this area, a hydrogeological and geochemical research has been conducted in this study. Samples of various types of waters were collected and analyzed for major cations, major anions and TFe, Al; selected coal and gangue samples were analyzed for fluoride contents. The F− concentration in AMD or AMD-affected waters ranged from 0.27 to 4.94 mg/L, and F− was mainly enriched in Na–SO4 and Mg–SO4 waters, but a relatively low F− concentration was found in the Ca–SO4 water. The F− concentration in the Ca–HCO3 water without being affected by AMD ranged from 0.01 to 0.20 mg/L. The elevated F− contents were found in the AMD, which is mainly influenced by the local coal mining activities, and it is resulted from the dissolution of fluoride-bearing minerals in coal-bearing clastic rocks, as well as the low pH values, high Al and Fe concentrations, high total dissolved solids and high Al/F ratio of the AMD. In addition, the dissolution/precipitation of carbonate rocks and special hydrogeological conditions determined the F− concentration in surface water. Meanwhile, the climate is also an influencing factor that cannot be ignored to affect the F− concentrations of surface water and groundwater.

Changes of blood zinc content in patients with coal-burning endemic fluorosis and its implication

Objective To assess the association of zinc(Zn) with coal-burning endemic fluorosis(coal-burning fluorosis),so as to provide an evidence for the role of Zn in preventing coal-burning fluorosis.Methods Fifty children with dental fluorosis and 100 healthy controls were selected from Wushan County by stratified sampling,and the same number of children and controls were also selected from Fengjie County.Thirty adults were selected from skeletal fluorosis patients in Duping Township of Wushan County,and 60 healthy controls were selected in the same township.Fasting blood samples were collected from all the participants for Zn determination.Urine samples were collected to examine urine fluoride content.Wilcoxon rank sum test was used to analyze the differences in Zn and fluoride contents between cases and controls and between the two counties.The association between blood Zn and urine fluoride was examined by Pearson linear correlation/Spearman rank correlation.Results The average urine fluoride contents were significantly higher in the child fluorosis cases than in the controls from both counties(P0.01);and the average blood Zn contents were significantly lower in the fluorosis cases than in the controls from both counties(P0.01).Moreover,the child cases and controls from Wushan County had significantly lower average blood Zn contents compared with those from Fengjie County(P0.05);the child fluorosis cases in Wushan County had a significantly lower urine fluoride content compared with those from Fengjie County(P0.05).The average urine fluoride content of skeletal fluorosis adults from Wushan County was significantly higher than that of controls,and the average blood Zn content was significantly lower than that of controls(P0.01).In addition,Pearson linear correlation/Spearman rank correlation showed a weak positive relationship between blood Zn and urine fluoride in both children and adults(P0.05,P0.01).Conclusion It is indicated that patients with fluorosis are generally Zn deficient,suggesting Zn deficiency might be a risk factor for fluorosis.

Coal-burning endemic fluorosis is associated with reduced activity in antioxidative enzymes and Cu/Zn-SOD gene expression

To study the effect of fluorine on the oxidative stress in coal-burning fluorosis, we investigated the environmental characteristics of coal-burning endemic fluorosis combined with fluorine content surveillance in air, water, food, briquette, and clay binder samples from Bijie region, Guizhou Province, southwest of China. The activities of antioxidant enzymes including copper/zinc superoxide dismutase (Cu/Zn-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and level of lipid peroxidation such as malondialdehyde (MDA) were measured in serum samples obtained from subjects residing in the Bijie region. Expression of the Cu/Zn-SOD gene was assessed by quantitative reverse transcriptase PCR (qRT-PCR). Our results showed that people suffering from endemic fluorosis (the high and low exposure groups) had much higher MDA level. Their antioxidant enzyme activities and Cu/Zn-SOD gene expression levels were lower when compared to healthy people (the control group). Fluorosis can decrease the activities of antioxidant enzymes, which was associated with exposure level of fluorine. Down-regulation of Cu/Zn-SOD expression may play an important role in the aggravation of oxidative stress in endemic fluorosis.

Myeloperoxidase Activity and Its Corresponding mRNA Expression as well as Gene Polymorphism in the Population Living in the Coal-Burning Endemic Fluorosis Area in Guizhou of China

The myeloperoxidase (MPO) activity and its corresponding mRNA expression as well as gene polymorphism were investigated in the population who live in the endemic fluorosis area. In the study, 150 people were selected from the coal-burning endemic fluorosis area and 150 normal persons from the non-fluorosis area in Guizhou province of China. The blood samples were collected from these people. The activity of MPO in the plasma was determined by spectrophotometer; the expression of MPO mRNA was measured by employing real-time polymerase chain reaction; DNAs were extracted from the leucocytes in blood and five SNP genotypes of MPO promoter gene detected by a multiplex genotyping method, adapter-ligation-mediated allele-specific amplification. The results showed that the MPO activity and its corresponding mRNA in blood were significantly increased in the population living in the area of fluorosis. The different genotype frequencies of MPO, including -1228G/A, -585T/C, -463G/A, and -163C/T, and the three haplotypes with higher frequencies, including -163C-463G-585T-1228G-1276T, -163C-463G-585T-1228G-1276C, and -163C-463G-585T-1228A-1276T, were significantly associated with fluorosis. The results indicated that the elevated activity of MPO induced by endemic fluorosis may be connected in mechanism to the stimulated expression of MPO mRNA and the changed gene polymorphism.

Corn and pepper fluorine survey in Zhenxiong county, a coal-burning borne endemic fluorosis area of Yunnan province

Objective To investigate the com and pepper fluorine in Zhenxiong county of Yunnan province, as well as the change of com and pepper fluorine after baked by coal, clay-mixed with cual for a relatively long-term, in order to provide a scientific basis for reducing fluorine intake. Methods The endemic areas of Yile, Wufeng's Songlinwan, Tangfang and Wufeng's Wugu in Zhenxiong county, and a non-endemic area Xiaguan in Dali city were selected as study sites. Ten samples of fresh corn and pepper were collected in each region, and fluorine was determined using acid leaching/potentiometry freshly and after baking or drying for 10 days or 4 months, respectively. Results The fluorine content of local fresh corn in Xiaguan of Dali city and Yile,Wufeng's Songlinwan, Tangfang, Wufeng's Wugu in Zhenxiong county were (1.31 ± 0.13),(1.65 ± 0.64),(1.92 ±0.37), (2.32 ± 0.49), (1.98 ± 0.66)mg/kg, respectively, and there were statistically significant differences across the regions(H = 27.871, P ＜ 0.05). The fluorine content of corn samples after baking or drying for 4 months were ( 1.82 ± 0.17), (26.43 ± 12.03), (39.27 ± 8.09), ( 14.27 ± 4.37), ( 14.33 ± 1.73)mg/kg, respectively, which were significantly higher than that of the fresh com in the corresponding region(all P ＜ 0.05 ), and there were statistically significant differences across the regions(H = 42.512, P＜ 0.05). The fluorine content of the local fresh chili were (3.34 ± 1.08), (3.44 ± 0.55), (3.47 ± 0.74), (3.46 ± 0.93)mg/kg, respectively, in the 4 observed places in Xiaguan of Dali city and Yile, Wufeng's Songlinwan, Tangfang in Zhenxiong county, and there were no statistically significant differences across the regions (F = 0.052, P ＞ 0.05 ). The fluorine content of pepper samples after baking or drying for 4 months were (7.01 ± 1.64), (226.07 ± 83.69), (179.36 ± 148.37), (54.51 ± 34.67)mg/kg,respectively, which were significantly higher than that of the fresh pepper in the corresponding region(all P ＜ 0.05 ),and there were statistically significant differences across the regions(H = 28.822, P ＜ 0.05). Conclusion Corn and chili fluorine is significantly increased after baked with coal and clay-mixed with coal by farmers in Zhenxiong county, a coal- burning borne endemic fluorosis area of Yunnan province. Key words: Fluorine; Capsicum; Zea mays; Curing-baking processing

Child Skeletal Fluorosis from Indoor Burning of Coal in Southwestern China

Objectives. We assess the prevalence and pathogenic stage of skeletal fluorosis among children and adolescents residing in a severe coal-burning endemic fluorosis area of southwest China. Methods. We used a cross-sectional design. A total of 1,616 students aged between 7 and 16 years in Zhijin County, Guizhou, China in late 2004 were selected via a cluster sampling of all 9-year compulsory education schools to complete the study questionnaire. Any student lived in a household that burned coal, used an open-burning stove, or baked foodstuffs over a coal stove was deemed high-risk for skeletal fluorosis. About 23% (370) of students (188 boys, 182 girls) were identified as high-risk and further examined by X-ray. Results. One-third of the 370 high-risk participants were diagnosed with skeletal fluorosis. Overall prevalence of child skeletal fluorosis due to indoor burning of coal was 7.5%. Children aged 12–16 years were significantly more likely to be diagnosed with skeletal fluorosis than children aged 7–11 years (OR = 1.84, 95% CI: 1.17–2.90; P = .0082). Four types of skeletal fluorosis were identified: constrictive (60.7%), raritas (15.6%), mixed (16.4%), and soft (7.4%). Most diagnosed cases (91%) were mild or moderate in severity. In addition, about 97% of 370 high-risk children were identified with dental fluorosis. Dental fluorosis was highly correlated with skeletal fluorosis in this study. Conclusions. Skeletal fluorosis among children may contribute to poor health and reduced productivity when they reach adulthood. Further efforts to reduce fluoride exposure among children in southwestern of China where coal is burned indoors are desperately needed.