A survey of epidemiological factors of coal-burning-borne endemic fluorosis in northeast of Chongqing

Objective To explore the risk factors of coal-burning-borne endemic fluorosis (endemic fluorosis) and to provide a scientific basis for making prevention and control strategy.Methods One hundred children with dental fluorosis and 30 adults with skeletal fluorosis who lived in Wushan county and Fengjie county,the endemic fluorosis regions northeast of Chongqing were randomly selected as the case group in 2010.One hundred healthy children and 30 healthy adults were selected from the population where the cases were selected from as the control group and 30 healthy external adults control were selected from Yubei district,a non-endemic fluorosis area.Fasting venous blood was draw from all subjects and the content of zinc (Zn),copper(Cu),calcium (Ca),magnesium(Mg),and ferrum(Fe) in venous blood was measured by atomic spectrophotometric.Instant urine was collected from all subjects and urinary fluorine was measured by fluorine selective electrode.We also did questionnaire survey to 100 dental fluorosis children and 100 control children about their situation of fluorine pollution and knowledge related to endemic fluorosis.Results Children's blood Zn of the ease group[(70.88 ±9.28) μmol/L] was lower than that of the control group [(75.53 ± 10.78)μmol/L],and the difference was statistically significant(P ＜ 0.05).But the average blood Cu content[(30.28 ± 2.58)μ mol/L] and the average urinary fluorine of the case group [(0.74 ± 0.36)mg/L] were significantly higher than that [Cu (28.45 ± 4.05)μmol/L and urinary fluorine (0.48 ± 0.21)mg/L] of the control group in children,respectively,and the differences was statistically significant(P ＜ 0.05).The average blood Zn content of adults in the case group[(91.13 ± 10.29)μ mol/L] was lower than that of the control group[(99.57 ± 11.73)μmol/L],and the difference was statistically significant (P ＜ 0.05).The average content of Mg[(1.57 ± 0.19)mmol/L],Fe[(8.17 ± 1.01) mmol/L] and urinary fluorine[(2.37 ± 1.01)mg/L] in the case group were higher than that [Mg(1.46 ± 0.16) mmol/L,Fe(7.72 ± 0.96) mmol/L and urinary fluorine(0.92 ± 0.85)mg/L] of the control group,respectively,and the differences were statistically significant(P ＜0.05).In the questionnaire survey,we found that the following were important related factors (OR values were 2.7335,0.3339,2.8428,0.4633,0.5439,0.4009,0.4805 and 0.3994,P ＜ 0.05) between the case group and the control group:using local coal for heating,furnaces and stoves improvement,eating local coal fire baked food,knowing the harm of endemic fluorosis to the health of human body,knowing endemic fluorosis can be prevented,knowing consuming baked food can cause endemic fluorosis,knowing drinking milk can prevent endemic fluorosis and having the habit of eating calcium tablets.Conclusions In addition to the main pathogenic element of fluorine,body Zn content is closely related to the process of coal-burning-borne endemic fluorosis in the two counties,fluorosis patients have lower blood Zn levels,Zn deficiency is an auxiliary factor in the etiology of fluorosis.Reduce the use of local coal for heating,do not consume the baked food,improve stoves,learn more knowledge about endemic fluorosis and ingest anti-fluoride elements can reduce the risk of endemic fluorosis. Key words: Fluoride poisoning; Elements; Risk factors; Data collection