Investigation of the coal fluoride in coal-burning type fluorosis areas in Chongqing.

[Objective] To grasp the relationship of fluoride content in coal with fluorosis in coal-burning type fluorosis areas in Chongqing and to provide a scientific basis for the analysis of the main fluoride source.[Methods] Investigations were done for dental fluorosis among the children of 8-12 years age and the status of skeletal fluorosis in people over the age of 16 sampled from the villages suffering from fluorosis in Pengshui County and Wushan County,with two villages from Yongchuan as controls.Furthermore,the fluoride contents in coal,coal mixed with soil,coal cinder,drinking water,soil,air from epidemic areas and non-epidemic areas were determined and used to estimate the fluoride content gained by the residents.[Results] Dental fluorosis of children as well as the detection rate of population over the age of 16 for skeletal fluorosis in epidemic areas were higher than that of non-endemic area.The difference of fluoride intake through the digestive tract was not obvious between the inhabitants in epidemic areas and non-epidemic areas,while fluoride intake through water were different,which did not exceed the national standard.But the air fluoride contents exceeded the national standard,and the fluoride intake through respiratory tract in endemic areas was 7.57 times higher than that in the non-endemic areas.[Conclusion] The fluoride source resulting in the coal-burning type fluorosis in Chongqing is coal-burning air fluoride pollution and the main fluoride intake pathway is respiratory tract.