Epidemiological analysis of tea-drinking-borne fluorosis among children in Haixi Prefecture of Qinghai Province in 2017

Objective To understand the epidemic situation of tea-drinking-borne fluorosis among children in Haixi Prefecture of Qinghai Province, and to provide basis for taking pertinent prevention and control measures. Methods In 2017, three townships (towns) were selected from five counties (cities) in Golmud, Delingha, Dulan, Ulan and Tianjun, Haixi, and one village (villages excluding excessive water fluoride) was selected from each township (town) as the investigation site. Fluoride content in drinking water, tea fluoride content and dental fluorosis in children aged 8 - 12 years were investigated. Water fluoride was determined using "Standard Test Method for Drinking Water" (GB/T 5750.5-2006); brick tea fluoride content was detected using "The Fluoride Content in Brick Tea" (GB 19965-2005); children's dental fluorosis was diagnosed using "Diagnosis of Dental Standard for Fluorosis" (WS/T 208-2011). Results Totally 75 drinking water samples were collected from each county (city). The water fluoride content ranged from 0.35 to 0.41 mg/L, with an average value of 0.37 mg/L, which was lower than the national drinking water fluoride standard of 1.00 mg/L. The fluoride content of 150 brick tea samples ranged from 206.0 to 796.0 mg/kg, with an average value of 629.8 mg/kg. A total of 1 325 children aged 8 - 12 were examined. The detection rate of dental fluorosis was 13.43% (178/1 325), the index of dental fluorosis was 0.27, and the overall epidemic intensity was negative. The epidemic intensity in Dulan and Tianjun counties was marginal. There were significant differences in the detection rate of dental fluorosis among children of different ages (χ2 = 35.26, P 0.05). Conclusions There is an epidemic of tea-drinking-borne fluorosis among children in 5 counties (cities) of Haixi Prefecture. Although the epidemic is mild, it should not be ignored. Health education and publicity work for tea-drinking-borne fluorosis should be strengthened. Key words: Fluorosis, dental; Child; Tea; Outcome assessment