To understand the prevalence state of drinking-tea type fluorosis in Hainan Prefecture, Qinghai Province, and provide scientific data for its prevention and control.

In 2016, a cross-sectional survey method was used to select five counties of Guide, Guinan, Xinghai, Gonghe and Tongde in Hainan according to "National Investigation Measure of Prevalence of Drinking-tea Type Fluorosis". In each county, 5 villages (towns) were selected according to the directions of east, west, north, south and center positions, and 1 administrative village was randomly selected in each village (town) as the survey site. All the children aged 8 to 12 years old at the survey site and 60 adults aged 16 years old and older at each survey site were selected as the survey subjects. We investigated the volume of brick-tea water consumed per day among objective population with questionnaire, and collected water, brick-tea water and urine samples (if each region has one water source, we collected one water sample, if this place have different water sources, we collected all the water samples from each water source; brick-tea water samples were collected based on different locations; more than 12 urine samples were collected in each survey site). The fluoride concentration in water, urine and tea water were detected with fluoride ion-selective electrode, the dental fluorosis of children aged 8-12 years were diagnosed by "Diagnosis of Dental Fluorosis" (WS/T 208-2011), and clinic skeletal fluorosis of population was diagnosed based on the "Diagnostic Criteria for Endemic Skeletal Fluorosis" (WS 192-2008).

The medians of fluoride in drinking water, drinking-tea water were 0.29 and 1.43 mg/L, respectively.The mean of daily fluoride intake of each person was 1.82 mg, and the geometric mean of urinary fluoride was 0.83 mg/L; the rate of dental fluorosis among children was 14.06% (559/3 975), its index was 0.24, the prevalence rate of clinic skeletal fluorosis among adult was 8.01% (119/1 484). The rate of dental fluorosis among children in Tongde County was the highest, about 15.96% (83/520), while the rate of dental fluorosis among children in Guinan County was the lowest, about 10.76%(111/1 032). The prevalence rate of clinic skeletal fluorosis among adult in Xinghai County was the highest, about 10.87% (30/276), while Tongde County was the lowest, about 5.75% (15/261).

The prevalence of drinking-tea type fluorosis is relative low. However, the local population are still under the risk of brick-tea with high fluoride, so it is necessary to strengthen the health education propaganda to keep the population healthy.

Fluorosis, dental; Urine; Skeletal fluorosis