| Objective： To analysis the main sources of fluorine in coal-burningpollution-type endemic fluorosis regions of Jiangxi province, screen those factors thatinfluenced the prevalence of dental fluorosis and evaluate fluoride intake levels of theresidents from fluorosis regions at this stage through using the methods ofepidemiological investigations and laboratory testing, so as to provide important andscientific basis for prevention and control strategies or measures of fluorosis.Methods：According to the statistical materials of endemic diseases from Jiangxiprovince at2009, the fluorosis regions including Huangchong village from Shanglitown and Taitang village from Changping township, Shangli county, Pingxiang cityand the non-fluorosis regions including Miling village and Caoyuan village, Qujiangtown, Fengcheng city of Yichun city were selected as the study field by multi-stagerandom sampling. The children of8~12years old from those regions were for thesurvey. Dental fluorosis was examined by Dean’s method in these sampled children.One copy of each sample covering drinking water (source water), surface water(paddy field water), outdoor air and indoor air (kitchen), rice, raw coal, honeycombbriquet and clay was collected according to the direction of east, west, south, northand center in the above four villages. Ten urine samples of each age children aged8~12years old in every village and the fluorine contents of them were determined bynational standards or industry standards.In addition, a1:1matched case-control study was implemented.50Patients aged8~12years old with dental fluorosis from the fluorosis regions in Pingxiang city werechose for the cases and50children with normal teeth who matched cases withsame-sex, age and residence were chose for the controls. Information was gathered bythe field questionnaire survey and the factors which influenced the prevalence ofdental fluorosis were screened. At the same time, dietary total fluoride intakes wereinvestigated by the combination of weighing method and24-hour dietary recallmethod. Results：(1) The prevalence of dental fluorosis was34.12%(58/170) in fluorosis regions;the proportion of dental fluorosis patients with very mild and mild was55.17%(32/58) and37.93%(22/58), respectively. The prevalence of dental fluorosis was10.05%(37/368) in non-fluorosis regions; the proportion of dental fluorosis patientswith very mild and mild was43.24%(16/37) and40.54%(15/37), respectively.There was statistically significant difference in the prevalence of dental fluorosisbetween fluorosis and non-fluorosis regions (x~2=44.668，P<0.05).(2) In fluorosis regions, children’s urine fluorine content was between0.29mg/L to2.82mg/L; geometric mean was1.07mg/L; the proportion of urine samplesthat fluorine content was above1.40mg/L was26.44%(23/87). In non-fluorosisregions, children’s urine fluorine content was between0.10mg/L to1.83mg/L;geometric mean was0.74mg/L; the proportion of urine samples that fluorine contentwas above1.40mg/L was14.04%(8/57).(3) Average fluorine content of indoor air was17.502μg/m~3in fluorosis regionsand7.424μg/m~3in non-fluorosis regions; the average fluorine content of indoor air influorosis regions was significantly higher than non-fluorosis regions (P<0.05). Therewere no statistically significant difference between fluorosis and non-fluorosisregions about fluorine contents from drinking water, surface water, outdoor air andrice (P>0.05). In fluorosis regions, the average fluorine content of raw coal,honeycomb briquet and clay was296.08mg/kg,327.11mg/kg and935.56mg/kg,respectively; in non-fluorosis regions, the average fluorine content of raw coal,honeycomb briquet and clay was109.61mg/kg,214.00mg/kg and565.00mg/kg,respectively; the average fluorine content of raw coal, honeycomb briquet and clay influorosis regions was significantly higher than non-fluorosis regions (P<0.05).(4) Multifactor conditional logistic regression analysis from the matchedcase-control study showed that father’s cultural level was higher (OR=0.133,95%CI:0.031~0.57), children often drink milk (OR=0.206,95%CI:0.056~0.754) andchildren brush their teeth many times every day (OR=0.199,95%CI:0.043~0.922)were protective factors of dental fluorosis in children.(5) Average dietary total fluoride intake was1.127mg/day people in cases and 0.869mg/day people in controls; there was no statistically significant differencebetween the two groups (P>0.05). Average dietary fluoride intake through drinkingwater was0.247mg/day people in cases and0.176mg/day people in controls,accounted for21.91%and20.26%of dietary total fluoride intake, respectively; therewas statistically significant difference between the two groups (P<0.05). Averagedietary fluoride intake through respiratory tract was0.159mg/day people in cases and0.131mg/day people in controls, accounted for14.11%and15.07%of dietary totalfluoride intake, respectively; there was no statistically significant difference betweenthe two groups (P>0.05). Average dietary fluoride intake through food was0.721mg/day people in cases and0.561mg/day people in controls, accounted for63.98%and64.57%of dietary total fluoride intake, respectively; there was no statisticallysignificant difference between the two groups (P>0.05).Conclusions：(1) The coal-burning pollution-type endemic fluorosis in Jiangxi provincebelongs to slight endemic fluorosis and the condition of diseases got well controlled.The sources of fluorine were extensive in fluorosis regions. The main causes whichlead to residents suffering from fluorosis were burning coal with high level of fluorideand clay.(2) Influencing factors of prevalence of dental fluorosis were screened by the1:1matched case-control study, and results indicated that father’s cultural level washigher (OR=0.133), children often drink milk (OR=0.206) and children brush theirteeth many times every day (OR=0.199) were protective factors.(3) Fluoride intakes of the population from coal-burning pollution-type endemicfluorosis regions of Jiangxi province were basically in normal range. |
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