ABSTRACT
Objective To identify changes in the occurrence of endemic fluorosis in order to provide scientific basis for making countermeasures. Methods Five villages from 14 counties of mild, moderate and severe fluorosis affected areas were selected by stratified cluster sampling every year in the whole province during 2006 - 2010. Water and urinary fluorine were determined by ion selective electrode method(GB/T 8538-1995); dental fluorosis of children 8-12 years old was diagnosed with Dean method; skeletal fluorosis was diagnosed according to "clinical indexing standards of endemic skeletal fluorosis "(GB 16396-1996), between 2006 and 2008, and "clinical diagnosis standard of endemic skeletal fluorosis"(WS 192-2008) between 2009 and 2010. Results A total of 25 diseased villages were surveyed, 14 with water sources changed, covered a resident population of 8005 people, beneficiary population 7154, and accounting for 89.37% of the resident population; not changed villages 11. In accordance with the "State drinking water health standards", in the 14 changed villages the fluoride in drinking water was qualified (≤ 1.20 mg/L), there were 3 schools whose water fluorine content exceeded the standard; among the 11 villages that did not change water sources 7 drinking water samples fluorine content exceeded the standard. Of the 8 to 12 years old children in villages with changed water sources, 363 of them were checked and 142 dental fluorosis were found, the detection rate of dental fluorosis was 39.12% (142/363); in villages with water sources not changed, 303 children were checked, the detection rate of dental fluorosis was 43.89%(133/303). Of sixteen and elder adults in water source changed villages, 6424 people were checked and 403 skeletal fluorosis were found, skeletal fluorosis detection rate was 6.27% (403/6424); 3572 people were checked in not changed villages, the detection rate of skeletal fluorosis was 13.89%(496/3572). In water sources changed areas, geometric mean of urinary fluoride was in the normal reference value(WS/T 256-2005, 1.40 mg/L)or less. Conclusions Endemic fluorosis is decreased in water improved areas, but in unimproved areas the disease is still severe, and control of endemic fluorosis is still an arduous task.