Study on the effect of different water-improving projects and different water-improving years on children's dental fluorosis in Tianjin / 中华地方病学杂志

ABSTRACT

Objective To investigate the influence of different water-improving defluoridation projects and different water-improving years on children's dental fluorosis,and to provide a scientific basis for further defluoridation of drinking water.Methods Totally 1/4 endemic fluorosis villages in all agricultural-related areas of Tianjin were selected by random sampling method from 2016 to 2017.The situation of water-improving defluoridation project was investigated in these villages.The ways of water improvement included municipal water supply,double pipe network,barreled water,low fluorine well and centralized water supply.The years of water improvement were ＞ 15,＞ 10-15,5-10,and ＜ 5 years,respectively.Totally 821 water samples (surface water,barreled water and groundwater) were collected.Fluoride ion selective electrode method was used for determination of water fluorine content.According to the "Diagnosis of Dental Fluorosis" (WS/T 208-2011),the prevalence of dental fluorosis in children aged 8 to 12 was examined.Results A total of 524 villages with drinking water endemic fluorosis and 35 870 children aged 8 to 12 were investigated in Tianjin.The water improvement rate was 73.28％ (384/524).Water fluoride qualified village accounted for 53.24％ (279/524).The detection rate of dental fluorosis was 47.98％ (17 209/35 870),the detection rate of dental fluorosis was different with different water improvement methods (x2 =1 955.742,P ＜ 0.05).Children's dental fluorosis detection rate in the area of municipal water supply was lower (33.19％,4 121/12 416),while that in double pipe network reconstruction area was 43.37％ (995/2 294).Children's dental fluorosis detection rates in the areas of barreled water supply,low fluoride well and centralized water supply were higher (58.47％,6 268/10 720;66.84％,1 719/2 572;53.75％,623/1 159).The median of water fluoride in the renovated area of municipal water supply was 0.24 mg/L,and the proportion of villages with water fluoride ≤ 1.2 mg/L was 100.00％ (133/133).With the increase in water-improving years (more than 10 years),children's dental fluorosis prevalence [＞ 15,＞ 10 ～ 15 years were 17.41％ (428/2 459),14.19％ (266/1 875)] in the areas of municipal water supply reached the control standards (≤30％).Conclusions The improvement of the municipal water supply network is thorough,which can meet the requirement of continuously ensuring the safety of drinking water for residents,especially those over 10 years.Other forms of water-improving need to be further optimized.