Objective:To explore the cause of death of 2 suspected Yunnan sudden unexplained death (YNSUD) cases in Dayao County, Yunnan Province.Methods:The field epidemiological investigation and autopsy of 2 cases of YNSUD in Dayao County from June 15 to 20, 2020 were conducted; and blood and tissue samples were collected for qualitative analysis of common poisons and drugs.Results:The areas where the two cases were located were all seriously ill villages with a history of YNSUD, and the time of death occurred in the onset season of YNSUD. There was no blood relationship between the 2 cases, no obvious abnormal symptoms before death, no special diet, no history of exposure to pesticides and other toxic chemicals, and the test results of common poisons were all negative. Autopsy pathological examination results showed that case 1 died of acute cardiac dysfunction caused by sudden acute myocardial infarction of coronary heart disease, and case 2 died of central respiratory and circulatory failure caused by spontaneous subarachnoid hemorrhage.Conclusions:The two cases are excluded from YNSUD through autopsy, and the cause of death is determined. It is suggested that emergency response should be taken as soon as possible for YNSUD cases, and autopsy should be actively carried out to clarify the cause of death from a pathological point of view.

Objective To study the effect of fluoride exposure on bone growth in zebrafish.Methods The zebrafish larvaes at 3 days post fertilization (3 dpf) were exposed to the conventional fish water and 25,50,100 mg/L of NaF for 5 days until the skeletal bone was formed (8 dpf) and the temperature was kept at 28 ℃.The fluoride content of zebrafish embryos was detected by F-ion selective electrode.The fluoride exposure model was re-established as the control group (0.0 mg/L),the low doses group (0.5,1.0,4.0 mg/L) and the high doses group (50.0,100.0 mg/L).The survival rates of the zebrafish embryos were calculated and the morphology of zebrafish embryos was observed under 40 times microscope.The zebrafish skeleton was stained with alizarin red.The staining areas and the integrated optical density (IOD) of the bone staining were quantitatively analyzed by digital microscope to analyze the sclerotic and osteoporosis of the skull.Results The fluoride contents of the control group and 25,50,100 mg/L NaF groups were (0.32 ± 0.01),(0.63 ± 0.01),(0.86 ± 0.02) and (1.21 ± 0.01) μg/150 embryos.Compared with the control group,the fluoride contents of zebrafish embryos in fluoride exposed groups were increased (P ＜ 0.05),and the dose-response relationship was obvious.The survival rates of zebrafish embryos in control group and fluoride exposed groups were 96.67％,96.67％,96.67％,98.33％,98.33％ and 98.33％.There was no significant difference among different groups (x2 =7.309,P ＞ 0.05);under a 40 times microscope,there were no obvious deformities of the spin in different groups;the areas of the alizarin red staining of the skull were 84 380.51 ± 11 711.41 in the control group,92 592.16 ± 7 143.81,92 164.85 ± 10 136.18 and 95 112.26 ± 13 721.91 in the low doses exposure groups (0.5,1.0,4.0 mg/L NaF),67 778.92 ± 8 597.11 and 64 272.93 ± 9 302.57 in the high doses groups (50.0,100.0 mg/L NaF).The areas of the alizarin red staining of the skull in the low doses exposure groups were significantly higher than that of the control group (P ＜ 0.05),while the high doses exposure groups were lower (P ＜ 0.05);the IOD of the alizarin red staining of the skull was 25 094.13 ± 6 571.86 in the control group,29 754.95 ± 3 836.45,28 747.36 ± 4 677.86 and 30 776.49 ± 5 589.63 in the low doses exposure groups (0.5,1.0,4.0 mg/L NaF),19 263.10 ± 4 754.72 and 18 202.58 ± 4 897.15 in the high doses groups (50.0,100.0 mg/L NaF).The IOD of the alizarin red staining of the skull in the low doses exposure groups was significandy higher than that of the control group (P ＜ 0.05),while the high doses exposure groups was lower (P ＜ 0.05).Conclusion Low doses of fluoride exposure may cause bone sclerosis in zebrafish embryos,while the high dose of fluoride exposure may cause osteoporosis.

Objective To investigate the relationship between single nucleotide polymorphism(SNP)of the peroxisome proliferator activated receptor γ (PPARγ) gene Rs1801282 and brick-tea type fluorosis. Methods From 2012 to 2013, this cross-sectional study was performed in 16 endemic fluorosis areas of brick-tea type in Inner Mongolia Autonomous Region,Qinghai and Xinjiang Uygur Autonomous Region of China,to select adults>18 years old as subjects, who were diagnosed as skeletal fluorosis by X-ray. All of the subjects filled in demography survey questionnaire; the survey contents included general characteristic s, and average daily brick tea intake. Drinking tea samples and urine samples of each subject were collected, and fluoride content of urine and brick-tea was determined via the ion selective electrode method (WS/T 89-2006). X-ray scintigraphy was used to diagnose skeletal fluorosis, according to the "Diagnostic Criteria of Endemic Skeletal Fluorosis" (WS/T 192-2007); the subjects were divided into skeletal fluorosis group (case group) and non-skeletal fluorosis group (control group). To collect venous blood 5 ml, whole blood DNA was extracted, and polymorphism at Rs1801282 of PPARγ was detected by MassARRAY time-of-flight mass spectrometry, to calculate odds ratio (OR) and 95% confidence interval (CI). Results There were 1 414 people included in this study,including 347 in case group and 1 067 in control group. By the Hardy-Weinberg balance test, the PPARγ gene Rs1801282 genotype was representative in case group, control group and each nationality (P > 0.05). The difference of PPARγ gene Rs1801282 genotype in case group and control group was not statistically significant (OR was 0.991, 95%CI: 0.704 - 1.395, the adjusted OR was 1.026, 95%CI: 0.707-1.489).The difference of PPARγ gene Rs1801282 genotype(CC,CG+GG)in case group and control group in different nationality was not statistically significant (Tibetan: OR was 1.400, 95%CI: 0.576 - 3.404, the adjusted OR was 1.258, 95%CI: 0.474 - 3.340; Kazak: OR was 0.898, 95%CI:0.516 -1.562,the adjusted OR was 0.936,95%CI:0.532 -1.648;Mongolia: OR was 1.148,95%CI:0.508-2.594, the adjusted OR was 1.644, 95%CI: 0.683 - 3.956; Han: OR was 1.058, 95%CI: 0.451 - 2.482, the adjusted OR was 0.959, 95%CI: 0.388 - 2.371; Russian: OR was 0.000, 95%CI: 0.000 - 0.000, the adjusted OR was 0.000, 95% CI: 0.000 - 0.000) with binary Logistic regression analysis. Conclusion We have found no association between SNP of PPARγ gene Rs1801282 and skeletal fluorosis of brick-tea type fluorosis in China.

Objective To observe the effect of fluoride on fibroblast growth factor 23 (FGF23) in bone tissue of mice,and to explore the role of FGF23 in fluoride-induced bone injury.Methods Sixty-four Balb/c mice,half male and female,were divided into 4 groups based on body weight via the random number table method and 16 mice were in each group.The mice in control group,low fluoride group,middle fluoride group and high fluoride group were treated with 0,25,50,and 100 mg/L F-distilled water,respectively.After three months,the mice were put to death and the prevalence of dental fluorosis was calculated.The fluoride contents in spine were detected via the fluoride-ion selective electrode method,serum content of calcium and phosphorus were detected by micro enzyme labeled method.The levels of FGF23,parathyroid hormone (PTH) and 1,25 dihydroxy vitamin D3 [1,25 (OH)2D3] in serum were measured by enzyme-linked immunosorbent assay.The FGF23 protein expression levels in bone tissue were determined by immunohistochemistry and Western blotting.Results The rates of dental fluorosis in low,medium and high fluoride groups were 75％ (4/16),100％ (16/16) and 100％ (16/16),respectively.Compared with control group [0 (0/16)] the differences were statistically significant (P ＜ 0.05).The levels of fluoride in the fluoride group [low,medium,high fluoride groups:(1 730.86 ± 165.90),(2 400.58 ± 286.65),(3 980.88 ± 511.65) mg/kg] were higher than that of control group [(854.30 ± 89.05) mg/kg,P ＜ 0.05].There was no difference in serum calcium content among groups (F =0.05,P ＞ 0.05).The contents of phosphorus in the serum of the medium and the high fluoride groups [(2.46 ± 0.32),(2.48 ± 0.73) mmol/L] were lower than those in the control and the low fluoride groups [(2.89 ± 0.45),(3.25 ± 0.69) mmol/L,P ＜ 0.05].The serum PTH and 1,25 (OH)2D3 content increased first and then decreased.The expression of FGF23 in middle and high fluoride groups [(660.84 ± 64.18),(638.74 ± 121.23) ng/L] was up-regulated compared with that of control group [(613.53 ± 98.18) ng/L].The expression of FGF23 protein in cortical bone increased gradually with the dose of fluoride.Western blotting results showed that the content of FGF23 protein in the bone tissue of mice was significantly increased in the low fluoride group (1.58 ± 0.46) and the middle fluoride group (1.40 ± 0.41) compared with that of control group (1.00 ± 0.41),the differences were statistically significant (P ＜ 0.05).Conclusions The phosphorus,FGF23,PTH,and 1,25 (OH)2D3 levels in the serum and FGF23 protein levels in the bone tissue of fluorosis mice have changed.It may be suggested that FGF23 interacts with PTH and 1,25 (OH)2D3 to influence the level of calcium and phosphorus metabolism in the body and participate in the formation of skeletal fluorosis.

Objective To study the urinary arsenic safety guideline value of a population for evaluating the arsenic exposure level in a certain population and providing evidence for the implementation of prevention and control measures in endemic arsenicosis area.Methods According to the data from the national high-arsenic drinking water sources screening in endemic arsenicosis area of drinking water type and quality supervision and inspection for water-improving project to decrease arsenic from 2005 to 2014,census data on arsenic poisoning in endemic arsenicosis area,data on surveillance of endemic arsenicosis,10 722 people with detailed personal information,complete water arsenic exposure data and accurate urinary arsenic detection data were selected to be the research objects.The relationship between urinary arsenic and water arsenic was analyzed based on the surveillance data of 4 501 people from 2013 to 2014.The safety guidance value of urinary arsenic was determined based on the geometric mean value of urinary arsenic in people exposed to water arsenic in the range of (0.050 ± 0.005) mg/L,and verified using the data of 6 221 people from 2005 to 2012.Every time,a random sample of 2 000 people was taken as the verification sample,the sensitivity and specificity of the index for determining whether water arsenic exposure exceeded the standard were determined by area under the ROC curve (AUC),and a total of 10 sample tests was performed.Results When the water arsenic concentration was less than 0.01 mg/L,the correlation coefficient of water arsenic concentration with urinary arsenic concentration was 0.097 (P ＜ 0.01);when the water arsenic concentration was more than 0.01 mg/L and less than 0.05 mg/L,the correlation coefficient of arsenic concentration with water arsenic concentration was 0.456 (P ＜ 0.01);when the water arsenic concentration was more than 0.05 mg/L,the correlation coefficient of water arsenic concentration with urinary arsenic concentration was 0.630 (P ＜ 0.01).With increase of water arsenic concentration,the concentration of urinary arsenic increased significantly,and the difference was statistically significant (x2 =2 337.956,P ＜ 0.01).When water arsenic concentration was in the range of (0.050 ± 0.005) mg/L,the urinary arsenic geometric mean was 0.032 mg/L.AUC analysis of 10 random samples of 2 000 people showed that the geometric mean of urinary arsenic was 0.032 mg/L in the population,which can accurately distinguish whether the water arsenic level exceeded 0.05 mg/L,and the AUC value was higher than 0.94.And the sensitivity and specificity were achieved 0.898 and 0.844.Conclusions The geometric mean of urinary arsenic is 0.032 mg/L,which can be used as a safety guideline value for urinary arsenic in the population.When the geometric mean of urinary arsenic exceeds this value,the population may be exposed to high arsenic.

Objective To investigate the significance of fibroblast growth factor 23 in metabolic bone disease of prematuriy.Methods 60 patients who had been treated in our hospital from March 2016 to March 2017 were included in this study.Blood biochemistry was examined two weeks after birth,and values of blood phosphorus, serum calcium and alkaline phosphatase were recorded. Serum levels of 25 hydroxyvitamin D3,parathyroid hormone and fibroblast growth factor 23 were detected two weeks after birth. 20 premature infants with metabolic bone disease were selected as a study group. 40 infants without metabolic bone disease were treated as a control group. Two weeks after treatment,the above indicators were measured and compared in the study group. Results Serum levels of 25 hydroxyvitamin D3,parathyroid hormone and fibroblast growth factor 23 were compared between the two groups 2 weeks after birth,the difference was statistically significant(P<0.05).Levels of serum parathyroid hormone and fibroblast growth factor 23 in the study group were not statistically significant after treat-ment(P > 0.05). Levels of 25 hydroxy vitamin D3 in the study group had statistically significant after treatment (P<0.05).Conclusions Early detection of fibroblast growth factor 23 can reflect metabolic bone disease in pre-term infants.It suggests that vitamin D should be adequately supplemented in early.

Objective To investigate the effects of fluoride on trabecular bone of the tibia and lumbar in BALB/c mice.Methods Totally 64 four-week-old BALB/c mice were randomly divided into 4 groups by weight,16 per group:control group (treated with distilled water) and 3 sodium fluoride (NaF) exposure groups (treated with NaF at 25,50 and 100 mg/L F-),respectively.At 12 weeks,mice were killed and blood,two hind limbs and lumbar were collected.Bone fluoride content and incidence rates of dental fluorosis were determined.Serum content of alkaline phosphatase (AKP) and acid phosphatase (ACP) were detected by micro enzyme labeled method.The ultrastructure of osteoblasts and osteoclasts in lumbar were observed via transmission electron microscope.The pathological changes of the trabecular bone of the tibia and the lumbar were observed under optical microscope,the percentage of trabecular area (％Tb.Ar) was measured with Image-Pro Plus (IPP) software.Results Bone fluoride contents of low,middle and high fluoride groups [(1 828.62 ± 102.93),(3 308.27 ± 185.63),(4 933.36 ± 301.16) mg/kg] were higher than that of the control group [(775.23 ± 92.56) mg/kg,all P ＜ 0.05].The incidences of dental fluorosis in the 4 groups were 0(0/16),47％(7/15),93％(14/15) and 100％(16/16),respectively;the difference was statistically significant (x2 =27.23,P ＜ 0.05).In middle and high fluoride groups,serum AKP [(18.30 ± 1.99),(24.50 ± 3.14) king unit/100 ml] and ACP [(11.97 ± 1.73),(11.31 ± 1.46) king unit/100 ml] were significantly higher than those of control [(14.63 ± 1.21),(9.07 ± 1.47) king unit/100 ml,respectively,all P ＜ 0.05].Under the electron microscope,osteoblast had developed organelles in each fluoride group,rough endoplasmic reticulum,Golgi body,and mitochondria were abundant,and nucleolus was obvious in the osteoblast.Osteoclast was rich in mitochondria,ruffled border clear and distributed phagocytic vacuoles in low fluoride group and middle fluoride group.Compared with the control group (17.03 ± 3.73),HE staining of tibia ％Tb.Ar in high fluoride group (28.79 ± 8.26) was significantly increased (P ＜ 0.05).The lumbar spine ％Tb.Ar in low,middle and high fluoride groups (15.87 ± 2.59,18.28 ± 0.89,21.99 ± 1.81) were higher than that of the control group (12.06 ± 1.76,all P ＜ 0.05].Conclusions BALB/c mice could be used as a model of skeletal fluorosis.Osteoblast and osteoclast are activated in BALB/c mice with skeletal fluorosis.Bone formation is more obvious than bone resorption and bone mass is increased.What is more,bone mass has increased more significantly in the lumbar spine of mice.

Objective To explore the effects of different doses of sodium fluoride (NaF) on cartilage lesion and expression of interleukin-6 (IL-6) in serum and cartilage tissue of Balb/c mice.Methods Sixty-four 5-week-old male Balb/c mice were divided into 4 groups based on body weight via the random number table method and 16 mice were in each group.The mice in control group were fed with distilled water,and experimental animals in low,middle and high fluoride groups were fed with distilled water containing NaF 25,50 and 100 mg/L,respectively.The mice were weighed once a week and fed for three months to establish the drinking water fluorosis model.The fluoride contents in spine were detected via the fluorin-ion selective electrode method.The pathological changes in articular cartilage and epiphyseal plate cartilage were observed through optical microscope.The levels of serum IL-6 and souble IL-6 receptor (sIL-6R) were detected via the enzyme-linked immunosorbent assay.The expression of IL-6 protein in articular cartilage and epiphyseal plate cartilage was examined by immunohistochemistry.Results From the sixth week of the experiment,compared with other 3 groups,the body weight of high fluoride group decreased significantly (all P ＜ 0.05);from the seventh week,compared with control and low fluoride groups,the body weight of middle fluoride group decreased significantly (all P ＜ 0.05);throughout the experiment,compared with control group,the body weight of low fluoride group had not changed significantly (all P ＞ 0.05).The fluoride contents of bone in control group,low fluoride group,middle fluoride group and high fluoride group were (842.46 ± 89.27),(1 705.05 ± 105.76),(2 614.17 ± 156.10) and (3 444.58 ± 233.69) mg/kg,respectively.The differences between groups were statistically significant (F =309.716,P ＜ 0.05),and fluoride contents of bone increased with increase of fluoride doses (all P ＜ 0.05).Under optical microscope,the cartilage tissue of control group was normal,while articular cartilage and epiphyseal plate cartilage showed different degrees of cartilage ossification in fluorosis mice and the changes increased with the increase of fluoride doses.The levels of serum IL-6 in control group,low fluoride group,middle fluoride group and high fluoride group were (5.98 ± 1.43),(7.54 ± 2.16),(5.25 ± 1.97) and (6.31 ±-1.36) ng/L,respectively.The differences between groups were statistically significant (F =3.840,P ＜ 0.05),low fluoride group was significantly higher than control group (P ＜ 0.05),and middle fluoride group was significantly lower than low fluoride group (P ＜ 0.05).The levels of serum slL-6R in control group,low fluoride group,middle fluoride group and high fluoride group were (0.83 ± 0.20),(0.93 ± 0.23),(0.82 ±0.27) and (0.92 ± 0.28) μg/L,respectively.The differences between groups were not statistically significant (F =0.738,P ＞ 0.05).Immunohistochemical results showed that articular cartilage full-layer cells in each group expressed IL-6 protein especially in the middle layer of chondrocytes,while IL-6 protein only expressed in hypertrophic chondrocytes of epiphyseal plate cartilage.Comparing with other groups,IL-6 positive cells were the most and had the deepest staining in low fluoride group.Conclusions Different doses of NaF could not only cause cartilage lesion,but also change the expression of IL-6 in serum and cartilage tissue of Balb/c mice.The results indicate that IL-6 may be involved in the cartilage lesion caused by fluoride.

Objective To detect the modification levels of H2AKll9 ubiquitination (H2AK119ub) and H2BK120ub,and to analyze the relationship between the levels of H2AK119ub,H2BK120ub and arsenic exposure.Methods A cross-sectional study was conducted in typical areas of drinking water type of endemic arsenicosis in Shanxi and Jilin provinces.Totally 281 residents who had drank local water for more 10 years were enrolled in this study,these participants were divided into control group (water arsenic content ＜ 0.01 mg/L),low arsenic exposure group (water arsenic content ranged 0.01-0.05 mg/L),medium arsenic exposure group (water arsenic content ranged ＞ 0.05-0.10 mg/L) and high arsenic exposure group (water arsenic content ＞ 0.10 mg/L).Among them,including 60 subjects in control group (20 males and 40 females),61 subjects in low arsenic exposure group (27 males and 34 females),50 subjects in medium arsenic exposure group (17 males and 33 females),and 110 subjects in high arsenic exposure group (40 males and 70 females).Drinking water and urine samples were collected and the arsenic content was detected by the method of atomic fluorescence spectrometry.After extracting leukocytes histone from the peripheral venous blood that collected from the subjects,the levels of H2AK119ub and H2BK120ub were detected by dot blotting.The levels of water arsenic,urinary arsenic,water arsenic accumulative intake,H2AK119ub and H2BK120ub were expressed as medium and quartile [M (P25,P75)].Results Age,body mass index (BMI),gender,smoking and alcohol drinking between control group and water arsenic exposure groups had no statistical differences (x2 =3.780,3.572,1.938,4.937,6.025,all P ＞ 0.05).Compared the contents of water arsenic [0.005 (0.003,0.006),0.024 (0.017,0.037),0.076 (0.057,0.084),0.150 (0.124,0.185) mg/L],the contents of urinary arsenic [0.011 (0.006,0.017),0.018 (0.004,0.072),0.061 (0.032,0.124),0.134 (0.069,0.223) mg/L],the water arsenic accumulative intake [0.342 (0.248,0.477),1.641 (1.012,2.324),5.273 (3.690,7.036),7.716 (5.608,12.053) mg] among the control,low,medium and high arsenic exposure groups,the differences were statistically significant (Hc =256.041,88.615,218.610,all P ＜ 0.01).Compared the levels of H2AK119ub [1.231 (0.856,1.817),1.244 (0.792,1.884),1.376 (0.743,1.981),1.390 (0.906,2.045)],H2BK120ub [0.350 (0.186,0.589),0.363 (0.152,0.678),0.428 (0.134,0.788),0.276 (0.146,0.453)] in human peripheral blood leukocytes among control,low,medium and high arsenic exposuregroups,the differences were not statistically significant (Hc =2.130,4.330,all P ＞ 0.05).There were no correlations between H2AK119ub and water arsenic content,water arsenic accumulative intake (r =0.104,-0.008,all P ＞ 0.05);there was a positive correlation between H2AK119ub and urinary arsenic content (r =0.166,P ＜ 0.05).There were negative correlations between H2BK120ub and water arsenic content,water arsenic accumulative intake (r =-0.183,-0.159,all P ＜ 0.05);there was no correlation between H2BK120ub and urinary arsenic content (r =-0.101,P ＞ 0.05).There was a negative correlation between H2AK119ub and H2BK120ub (r =-0.127,P ＜ 0.05).Conclusion External exposure to arsenic may change the levels of H2BK120ub in human peripheral blood leukocytes.

Objective To investigate the relationship between Cytochrome P-450 1A1 (CYP1A1) gene polymorphism and the ethnic differences to brick-tea fluorosis and the gene-environment interaction.Methods Inhabitants over the age of 16 years old in Inner Mongolia,Qinghai and Xinjiang were investigated.The questionnaire survey included basic information,dietary survey and total fluoride intake,and peripheral venous blood was collected.The CYP1A1 gene single nucleotide polymorphism (SNP) genotyping was determined using mass spectrometry;the diagnosis of skeletal fluorosis was based on the X-ray method;combined genetic factors with environmental factors,the interaction of gene-environment was analyzed.Results In the 1 414 copies of whole blood samples (308 Tibetans,290 Kazakhs,261 Mongolians,425 Han people,130 Russians),CYP1A1 genes rs1048943 sites were typed into AA,AG and GG genotypes,and gene distribution met Hardy-Weinberg equilibrium (P ＞ 0.05).The frequencies of genotypes AA,AG and GG in Tibetans were 55.8％ (172/308),37.3％ (115/308) and 6.8％ (21/308),respectively;the frequencies of the three genotypes in Kazakhs were 69.7％ (202/290),27.6％ (80/290) and 2.8％ (8/290),respectively;the frequencies of the three genotypes in Mongolians were 60.5％ (158/261),36.0％ (94/261) and 3.4％ (9/261),respectively;the frequencies of the three genotypes in Han people were 60.9％ (259/425),33.6％ (143/ 425) and 5.4％ (23/425),respectively;the frequencies of genotypes in Russians were 72.3％ (94/130),26.9％ (35/130) and 0.8％ (1/130),respectively;the differences of the three genotype frequencies between different ethnic groups were statistically significant (x2 =24.757,P ＜ 0.05).The skeletal fluorosis detection rates in different ethnic from high to low were Tibetans (39.94％,123/308),Kazakhs (33.79％,98/290),Mongolians (22.22％,58/261),Han people (13.41％,57/425) and Russians (8.46％,11/130),and the differences were statistically significant (x2 =100.156,P＜ 0.05).Skeletal fluorosis detection rates of different genotypes were AA (24.18％,214/885),AG/GG (25.14％,133/529),the difference was not statistically significant between the groups (x2 =0.165,P ＞ 0.05).After the ethnic stratification,the differences were also not statistically significant (P ＞ 0.05).Only in the group of Tibetans whose urine fluoride level was 1.6-3.2 mg/L and Mongolians under age 45 were found that the G gene was one of the risk factors in skeletal fluorosis [OR =2.035,95％ CI (1.003-4.128);OR =5.602,95％CI (1.461-21.479)];G gene might be a protective factor in the Mongolians aged 45 years and over [OR =0.422,95％CI(0.190-0.938)].Conclusion This study does not find a positive correlation between CYP1A1 gene polymorphism and the ethnic differences to bricktea fluorosis.