Analysis on changes of fluoride in rural centralized water supply in Inner Mongolia Autonomous Region from 2014 to 2018 / 中华地方病学杂志

ABSTRACT

Objective:To understand the situation and distribution of fluoride in rural centralized water supply in Inner Mongolia Autonomous Region (Inner Mongolia for short), and provide a reference for adjustment of prevention and control measures.Methods:From 2014 to 2018, 836, 947, 1 033, 1 068, 1 099 rural centralized water supply monitoring sites were designated in 77 banners (counties, districts) separately in Inner Mongolia, and factory water and tip water samples were collected during plentiful phase and exhausted phase every year, respectively, and fluoride content was tested. Descriptive analysis was done according to time, water period (plentiful phase and exhausted phase), water sample type (factory water and tip water), water treatment method (conventional treatment, sedimentation and filtration, only disinfection and untreated), area distribution [eastern region (Hulunbuir, Xing'an League, Tongliao and Chifeng), central region (Hohhot, Baotou, Ulanqab and Xilinhot) and western region (Ordos, Bayannur and Alashan)], and the results were analyzed visually by ArcMAP 10.2.Results:From 2014 to 2018, 3 251, 3 671, 4 058, 4 087 and 4 395 water samples were collected, the medians fluoride were 0.69, 0.70, 0.69, 0.64 and 0.66 mg/L, and the annual compliance rates of fluoride were 80.31% (2 611/3 251), 81.83% (3 004/3 671), 83.14% (3 374/4 058), 85.91% (3 511/4 087) and 84.57% (3 717/4 395). The difference of compliance rate of fluoride in rural centralized water supply in different years was statistically significant (χ 2=51.748, P < 0.01), and the compliance rate of fluoride showed an increasing trend with the years (χ 2=41.140, P < 0.01). The compliance rates of fluoride in plentiful phase and exhausted phase were 83.36% (8 128/9 750) and 83.29% (8 089/9 712), respectively, and the difference was not significant statistically (χ 2=0.020, P > 0.05). As for water sample type, the compliance rates of fluoride in factory water and tip water were 83.55% (6 583/7 879) and 83.17% (9 628/11 576), and the difference was not significant statistically (χ 2=0.485, P > 0.05). The difference of compliance rate of fluoride in different water treatment methods was statistically significant (χ 2=192.014, P < 0.01). The compliance rates of fluoride in water with conventional treatment and only disinfection were higher [95.51% (404/423) and 94.44% (986/1 044)]; and the untreated water had the lowest compliance rate of fluoride [81.75% (13 073/15 991)]. There was a statistically significant difference in compliance rates of fluoride in the eastern, central and western regions (χ 2=629.256, P < 0.01), with the eastern region had the highest compliance rate of 89.17% (7 337/8 228); the central region had the lowest compliance rate of 74.67% (5 391/7 220). The visualization results showed that the compliance rate of fluoride was obviously low in the central region north of Yin Mountains and west of Greater Higgnan Mountains. Conclusions:From 2014 to 2018, the compliance rates of fluoride in rural centralized water supply increase year by year, and some achievements have been made in fluorine reduction and water improvement project in Inner Mongolia. However, there are still some rural areas with low level of water fluoride compliance rates which mainly distribute in the central region of Inner Mongolia in the north of Yin Mountains and west of Greater Higgnan Mountains. The current focus of prevention and control should be shifted from "general control" to "precise fluorine control". In the future, it is necessary to implement treatment projects in key areas of fluorine pollution from the aspects of policy implementation and technological innovation to ensure the drinking water safety of local rural residents.