Study on the changes in the state of endemic fluorosis by coal-burning pollution in Guizhou Province

Objective To explore the changes in the state of endemic fluorosis caused by domestic coal-burning pollution in the key endemic regions of Guizhou Province,providing scientific basis for the further investigation of preventive or control demand.Methods Based on the results of the investigation in the whole province in the year 2000,stratified and random sampling methods were adopted,and the investigation villages were chosen in the A endemic regions(very marked in prevalent intensity of dental fluorosis)and B regions(middle in prevalence of dental fluorosis),respectively.The dental fluorosis of the children aged 8 to 12 years old in the school of the villages of A regions and B regions was checked,respectively.The results were compared with that of 2000.At the same time,the total fluoride intake daily per person was calculated based on the laboratory detection results of fluoride in the samples of rice,corn,chili pepper,drinking water,coal and clay(to be mixed with the coal powder).Results The concentration of fluoride in the drinking water was much lower compared with the National Standard.The contents of fluoride in the coal and clay were higher than the Standard,and the content in the clay was 3.5 times of that in the coal.The contents of fluoride in the corn and chili pepper were also higher than the Standard,but the pollution became lower compared with that of 2000's investigation.The total intake of fluoride was above the Standard in all the investigation counties except for Changshun and Longli County.The chili pepper is becoming the main fluoride-carrying media in the endemic regions.In the A regions,compared with the results investigated in 2000,the detection rate of dental fluorosis had no obvious changes,and the cases were mainly distributed in the mill and middle.The prevalent intensity of dental fluorosis in all counties was still marked or very marked,but was lower down to the middle in Qianxi County.In the B endemic regions,compared with the investigated results of 2000,the detection rate of dental fluorosis in the children aged 8 to 12 decreased by 29.71%,in which the decrease was 64.27% in Longli County.The cases were chiefly distributed in the very mild and mild,and the very mild occupied for above 50%.Except for Liuzhi,the endemic degree of dental fluorosis in all investigated counties was decreased markedly,and Longliu became non-prevalent regions.Conclusions The prevalent state in the middle endemic regions was significantly decreased and the control effects were obvious,through recent years' comprehensive control measures,but in the historic severe regions the prevalence was still severe and the control tasks remain very hard.It is the key measure to avoid chili pepper pollution,at the same time of improving and installing the cooking ranges,in the existing controlling the coal-burning endemic fluorosis in Guizhou province.