Drinking-water type of fluorosis in Shaanxi province in 2009: an analysis of surveillance results

Abstract

Objective To investigate running conditions of water improvement projects and role of these projects in reducing fluoride in drinking-water type of fluorosis in Shaanxi province, and provide a scientific basis for prevention and control of disease. Methods Forty-eight villages of 16 counties in Xi'an, Baoji, and Yulin cities of Shaanxi province were monitored in 2009. Five water samples were collected randomly in water unimproved monitoring villages by position of east, west, south, north, and center parts. In water improved monitoring villages, 3 tap water and one source water samples were collected. fluoride was tested using fluoride ion selective electrode method according to Standard Testing Methods for Drinking Water (GB/T 5750-2006). All school children aged 8 to 12 in monitored villages were examined their dental fluorosis using Dean criteria. All people over 16 years old were examined clinical skeletal fluorosis, and 30% of project counties were randomly selected, then randomly selected one village among these counties, clinically diagnosed patients with skeletal fluorosis were examined again by X-ray using Diagnostic Criteria of Endemic Skeletal Fluorosis(WS 192-2007). Urine samples of 30 children aged 8 to 12 and of 20 adults over age of 16 were randomly collected, urinary fluoride was tested according to the Determination of Urinary Fluoride by Ion Selective Electrode Method (WS/T 89-19%). Results Of 22 water improvement projects that in normal operation, fluoride level of 8 source waters exceeded standard, accounting for 36.36%(8/22), and projects scrapped 5. Two hundred and two water samples were tested. In water improved historical diseased areas, median of water fluoride of source water and tap water were 0.72,0.62 mg/L, respectively, and average rate of water fluoride exceeded standard ere 36.36%(8/22) and 31.94%(23/72), respectively. In water unimproved historical diseased areas, median of water fluoride was 1.00 mg/L, and average rate of water fluoride exceeded standard was 39.81%(43/108). Detection rate of dental fluorosis among children aged 8 to 12 was 16.06% (367/2285), dental fluorosis index was 0.30, and prevalence was negative. Detection rate of clinical skeletal fluorosis among adults over 16 years old was 5.09%(1542/30 272), a totally of 198 people had X-ray film taken, positive 68, positive detection rate was 34.34%(68/198). One thousand and fifty-one copies of children's urine samples were tested, geometric mean of urinary fluoride was 0.95 mg/L; nine hundred and fourteen copies of adults urine samples were tested, geometric mean of urinary fluoride was 1.16 mg/L Conclusions Drinking-water type of fluorosis affects a large area in Shaanxi province, disease is still serious, and task of prevention remains very arduous. Further intensify water improvement project in diseased areas, and strengthen disease monitoring, health education and water improvement project management is key to prevention and control of endemic fluorosis. Key words: Fluoride poisoning; Drinking; Urine; Fluorosis, dental; Osteofluorosis