| ObjectiveAnimal model were established by the way of gastrointestinal and respiratorytract exposure, and the effect of two way of fluorine absorption on rat were observedand compared with both of the fluoride absorptive, offered experimental basis aboutmain pathogenic way for endemic fluorosis in fluorosis area. Provide further evidenceto work out the effective measures about prevention for coal endemic fluorosis.Methods88six-week-old SD male rats were randomly divided into11groups. Onegroup was designed as normal control group, other six groups were designed as fiverespiratory tract exposured groups,0.6mg/kg1.2mg/kg2.4mg/kg3.6mg/kg4.8mg/kgof corn-burning coal in fluorosis areas were added respectively and fivegastrointestinal exposured groups of0.48mg/m3,0.6mg/m3,0.72mg/m3,0.84mg/m3,0.96mg/m3respectively. The time of exposure is8hours every day (4hours in themorning and in the afternoon, respectively), rats were fed with a standard diet. Therats of control group were also fed with standard diet, and bred in the air with lowlevel of fluorine, and the experiment would take3months. The rats in the sub-groupof food fluorosis were raised in cages24hours after the exposure time of30days,60days and90days respectively. We recorded the consumption level of forage and fecalexcretion in24hours, and assayed the content of fluorine in the fecal with F-ionselective electrode. After the exposure, rat bilateral femora bone mineral density wasassayed with dual energy X-ray absorptiometry. Serum was isolated after putting ratsto death bloodletting from femoral artery, and the content of serum fluorine wasdetermined by Fion selective electrode. The content of bone fluorine was determinedby pipe type with furnace temperature combustion hydrolysis. Results1. The various fluorotic teeth were observed from each dose group ingastrointestinal and respiratory tract exposure after90days, the morbidity and thecontent of lesion of fluorotic teeth among every group of two exposure ways hadsense in statistics (P <0.01). With the increase of exposure dose, the morbidity anddamage content of fluorotic teeth increased.2. The concentration of fluorine in serum and urine, the content of fluorine inbone and bone mineral density among each dose group of respiratory tract exposurehad statistics significance (P <0.05). The concentration of fluorine in serum andurine, the content of fluorine in bone and the level of bone mineral density rose withthe increase of the content of fluorine in forage.3. The concentration of fluorine in serum and urine, the content of fluorine inbone and bone mineral density among each dose group of gastrointestinal exposurehad statistics significance (P <0.05). The concentration of fluorine in serum andurine, the content of fluorine in bone and the level of bone mineral density rose withthe increase of the content of fluorine in forage.4. Between the2.4mg/kg group having fluorine in the forage of respiratory tractexposure and0.84mg/m3group having fluorine in gastrointestinal exposure, theconcentration of fluorine in serum and urine, the content of fluorine in bone and bonemineral density had no sense in statistics. The fluorosis effect which forage with2.4mg/kg fluorine was fed to rats was correspond to which air with0.84mg/m3fluorine was inhaled8hours every day.5. The results of factorial analysis showed that the influence of respiratory tractexposure and the exposure dose on absorption rate of fluoride in forage had no sensein statistics (F=1.84, P>0.05), and the main effect of influence of exposure time onabsorption rate of fluoride in forage also had no sense in statistics (F=1.35, P>0.05),the influence of exposure dose and time on absorption rate of fluoride in forage hadno interaction (F=0.76, P>0.05). The absorption rate of fluorine in forage byrespiratory tract exposure was58.23%and the absorption rate of fluorine in air by respiratory exposure was97.48%.Conclusions：1. There were dose-response relationship between serum fluoride concentrationsin rats, urinary fluoride concentrations, bone fluoride content, bone mineral densityand exposure doses.2. The forage of the fluoride content with2.4mg/kg was eaten by rats and the airwith fluoride concentration0.84mg/m3in8hours per day were inhaled caused aconsiderable effect.3. The rate of fluoride absorption in the digestive tract exposed to feed hasnothing to do with the exposure dose and exposure time, the rate of fluorideabsorption was58.23%; respiratory exposure, the rate of air fluorine absorption was97.48%;4. Fluoride of burning coal fluorosis areas of coal combustion released wasentered the body by baking food or pollute the indoor storage of food. |
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