Investigation and analysis of drinking-tea fluorosis in Lhasa from 2016 to 2018 / 中华地方病学杂志

ABSTRACT

Objective:To investigate the prevalence of drinking-tea fluorosis from 2016 to 2018 in Lhasa City, Tibet, and to provide clues and basic data for preventing this disease.Methods:According to the stratified cluster sampling method, Mozhugongka County and Nimu County in 2016, Dazi District in 2017, Chengguan District, Duilongdeqing District and Qushui County of Lhasa City in 2018 were selected as survey counties (districts), each county (district) selected 1 township (town) according to the 5 directions of east, south, west, north, and middle, and each township (town) selected 1 to 2 administrative villages as survey points, and each survey point recruited villager volunteers aged ≥18 years for survey subject. All volunteers were tested for dental fluorosis (Dean method) and skeletal fluorosis (X-ray), and samples of drinking water, brick tea consumed at home and residents' urine were collected for water fluoride, tea fluoride, and urine fluoride testing.Results:A total of 30 water samples were collected, and the water fluoride content was all < 1.0 mg/L. The average fluorine content was 1 167.5 mg/kg among 314 samples of brick tea investigated in this study. The qualification rate of brick tea in each survey county was 0 - 16.7%. The daily intake of fluoride in brick tea per person was 6.4 mg. The prevalence of dental fluorosis was 18.1% (350/1 929) among all enrolled participants, 4 of the 6 survey counties (districts) had varying degrees of dental fluorosis. A total of 1 637 urine samples were collected and detected, and the urine fluorine level ranged from 0.01 to 11.01 mg/L, with a geometric mean of 1.07 mg/L. The urine fluorine levels in all investigated counties (districts) were under the standard limits (≤1.6 mg/L). Eight adults were diagnosed with skeletal fluorosis of degree Ⅰ via X-ray detection, with a detection rate of 0.4% (8/1 929). Totally 20.2% (390/1 929) of people reported suffered from two or more joint disease. Furthermore, 6 counties (districts) in Lhasa City were identified as mild drinking-tea type endemic fluorosis disease areas.Conclusion:From 2016 to 2018, the fluorine content of brick tea in Lhasa has exceeded the standard seriously, dental fluorosis is mildly prevalent in some counties (districts), and 6 counties (districts) are all mild tea-drinking fluorosis areas.