The Analysis of Surveillance Results about Water-endemic Fluorosis from 1991 to 2007 at Yanchi County-Statelevel Surveillance Stations in Ningxia

Objective To explore the changes about the endemic fluorosis after improving the water quality at Yanchi area,and to provide scientific data for prevention and treatment for endemic fluorosis.Methods The prevalence of dental fluorosis in 8～12-year-old and adults over the age 16 were investigated,and fluoride in household drinking water that was improved and 8～12-year-old child's urine was determined.Results From 1991 to 2007,by improving water quality projects,the water fluoride qualified rate was 83.3% in 1991 and water fluoride qualified rate was 21.43% in 2003,2004.In three surveillance villages,the prevalence of dental fluorosis of 8～12-year-old and Geometric mean of urinary fluoride overall showed downward trend.The child dental fluorosis rate and the geometric mean urinary fluoride were higher than those of national standards in the most years.The positive rate of adult skeletal fluorosis clinical symptoms and X-ray detection showed increasing as the population's age rise.Some resident's drinking water fluoride content exceeded standards.Conclusion The changing and improving of water source is the best ways for prevention for endemic fluorosis at the water-endemic fluorosis areas.The key ways to reduce the incidence rate of fluorosis are to provide water with low fluoride stability and ensure the project to run well.