Health Risk Assessment of Fluoride in Drinking Water from Anhui Province in China

Environ Monit Assess (2013) 185:3687–3695 DOI 10.1007/s10661-012-2820-9 Health risk assessment of fluoride in drinking water from Anhui Province in China Hong-jian Gao & You-qian Jin & Jun-ling Wei Received: 4 February 2012 /Accepted: 25 July 2012 /Published online: 19 August 2012 # Springer Science+Business Media B.V. 2012 Abstract This study analyzes the concentrations and safety in drinking water and controlling endemic health risks of fluoride in 249 drinking water samples fluorosis in different regions of Anhui Province. collected from different regions of Anhui Province in China. Results indicated that fluoride content in drinking Keywords Fluoride concentrations . Drinking water . waterrangedfrom0.12to1.94mgL−1 (mean00.57 mg Health risk assessment . Endemic diseases L−1) in the following order: Huaibei plain region > Jianghuai hill region ≈ Dabieshan mountainous region > plain along the Yangtze River region > Introduction southern Anhui mountainous region. The fluoride contents were less than 0.50 mg L−1 in 66.66 % of the Fluorine is the lightest halogen and one of the most drinking water samples, 0.51–1.0 mg L−1 in 23.29 %, reactive of all chemical elements (Kaminsky et al. − and higher than 1.0 mg L 1 in 12.04 %. The fluoride 1990). It is also the most electronegative element, levels in some samples were lower than the which indicates its strong tendency to acquire a nega- recommended values for controlling dental caries tive charge and form F− ions in solution (Helm 1985). − (0.50–1.0 mg L 1). The total fluoride intake from Fluorine is found as fluoride in the environment, drinking water was between 0.14 and 2.33 mg per day which together represent about 0.06–0.09 % of the in different regions of the province, supposing an earth’s crust. Fluoride occurs naturally in rock, soil, individual consumes 1.2 L of water per day. Therefore, water, plants, and animals (Ozsvath 2009; Walna et al. measures should be taken to increase fluoride intake in 2007; Zhu et al. 2007). Fluoride is absorbed by body the Jianghuai hill region, Dabieshan mountainous tissues, such as teeth and bones, when ingested by region, plain along the Yangtze River, and southern humans and other animals (Harrison 2005). Different Anhui mountainous region to control dental caries. On forms of fluoride exposure are critical and have shown the other hand, the fluoride levels must be reduced in the to affect fluoride content in the body, thus increasing Huaibei plain region to decrease endemic fluorosis. The the risk of fluoride-prone diseases (Harrison 2005). results serve as crucial guidelines for managing fluoride Fluoride in drinking water has beneficial effects on teeth at low concentrations (<1.0 mg L−1), such as : : preventing and reducing the risk of tooth decay H.-j. Gao (*) Y.-q. Jin J.-l. Wei (Harrison 2005;Ozsvath2009). However, concentra- School of Resources and Environment, tions lower than 0.5 mg L−1 intensify the risk of dental Anhui Agricultural University, Hefei 230036, China caries (Ozsvath 2009). Fluoride can also be detrimental − e-mail: [email protected] at concentrations exceeding 1.5–2.0 mg L 1 (WHO 3688 Environ Monit Assess (2013) 185:3687–3695 1984). High concentrations of fluoride increase the supply for both excessive and insufficient fluoride risks of dental and skeletal fluorosis depending on content. the level and period of exposure (Hileman 1988; Kaminsky et al. 1990). Fluoride is found most frequently in ground water Materials and methods at higher concentrations depending on the nature of rocks and natural fluoride-carrying minerals at certain Study area depths (Guo et al. 2007). Natural fluoride concentrations in ground water range from trace quantities to Anhui Province (114°54′–119°37′ E, 29°41′–34°38′ N) over 25 mg L−1 (Harrison 2005). High levels of fluo- is an inland province in Southeast China with a popula- ride in drinking water have been detected in India tion of over 64.6 million. It stretches over the Yangtze (Dhiman and Keshari 2006), Turkey (Oruc 2008), River and the Huaihe River. The province is divided into Pakistan (Tahir Shah and Danishwar 2003), and China five topographical zones from north to south: (1) The (Guo et al. 2007). Huaibei plain region, an alluvial plain on both banks of China is one of the countries that suffered from the Huaihe River, is part of the North China plain and serious endemic fluoride diseases, such as dental caries makes up half the farmland of the province. (2) The and skeletal fluorosis (Wang and Huang 1995). More Jianghuai hill region is the watershed of the Huaihe than 26 million people suffer from dental fluorosis, and River and the Yangtze River valleys. (3) The Dabieshan over one million suffer from skeletal fluorosis (Lennon mountainous region in the west extends to the east to et al. 2004). In Anhui Province of China, over three join the Huoshan Mountains. (4) The plain along the million and 0.1 million people reportedly suffer from Yangtze River, which is part of the Middle-Lower dental and skeletal fluorosis, respectively; most of the Yangtze River Plain, includes the flatlands along the cases are found in Bozhou, Fuyang, Suzhou, Huaibei, Yangtze River and the Chaohu Lake basin. (5) The Huainan, and seven other cities (Deng 2006). The high southern Anhui mountainous region is located south of fluoride content in both shallow and deeper ground the Yangtze River side plain. water is the major cause of endemic fluorosis in the province (Deng 2006). Instruments and Reagents Several measures have been conducted to adjust fluoride in drinking water. Fluoridation of public water The Thermo Scientific Orion 4-Star plus pH/ISE meter supplies is one of the most popular approaches to (9609BNWP fluoride ion-selective electrode and increase fluoride in drinking water to reduce the preva- 096019 stirrer probe) was purchased from Thermo Fish- lence of dental caries (Fawell et al. 2006). Three specific er Scientific Inc., USA. For the fluoride stock solution treatments, namely, chemical coagulation, activated alu- (1,000 mg L−1), 0.2210 g of sodium fluoride (dried 2 h mina, and membranes, have been successful in remov- at 110 °C and stored in a desiccator) was dissolved in ing fluoride from drinking water (Fawell et al. 2006). distilled water, diluted to 100 mL in a volumetric flask, However, most of the rural inhabitants in China are and then stored in a clean polyethylene bottle. Prior to accustomed to consuming drinking water collected from use, the fluoride standard solution was diluted to varied private ground water wells without any safe treatments concentrations with distilled water. The total ionic (Dai et al. 2004). Therefore, the low or high levels of strength adjustment buffer (TISAB) was prepared via fluoride in drinking water still pose threats for human the following steps: Approximately 57.0 mL of glacial health (Guo et al. 2007). acetic acid, 58.0 g of sodium chloride, and 68.0 g of This study aims to investigate the concentrations sodium citrate were added to 700 mL of distilled and distributions of fluoride in drinking water collected water in a 1.0-L beaker. Solution pH was adjusted from the rural and city inhabitants from different regions between 5.0 and 5.5 with 5 M NaOH after dissolving of Anhui Province. The health implications posed by and cooling to room temperature. The solution was fluoride levels in drinking water were also analyzed transferred to a 1,000-mL volumetric flask, diluted to according to the national and international quality the mark with distilled water, and finally stored in a standards. The results of the study would be helpful clean polyethylene bottle. All reagents used in this in working out strategies for safe drinking water study were of analytical grade. Environ Monit Assess (2013) 185:3687–3695 3689 Drinking water sampling (9609BNWP fluoride ion-selective electrode) following the method developed by Gao et al. (2010). The From 10 to 25 February 2009, 249 drinking water temperature of the drinking water samples was bal- samples were collected from the local inhabitants from anced to room temperature before the analysis. Ap- different regions of the province (Fig. 1). The sam- proximately 20.0 mL of drinking water and 20.0 mL pling sites were widely distributed in different regions of TISAB were added to a 50-mL polyethylene to assure the representative of water sample collection. beaker and completely mixed using a clean glass Well water from five rural inhabitants and public water bar. The fluoride ionic electrode tip was then im- from five city inhabitants in each sampling site were mersed into the mixed solution, and the meter read- randomly collected and then completely mixed to ing was recorded as soon as the reading was stable. form one water sample. Prior to sampling, 1.0-L poly- Triplicate experiments were performed for each ethylene bottles were washed with drinking water drinking water sample. three times. Water samples were collected from public Fluoride at concentrations of 0.25, 0.50, 1.0, water supply systems in cities and from wells in rural 2.0, 4.0, and 6.0 mg L−1 were spiked in double- regions into 1.0-L clean polyethylene bottles during distilled water to examine the assurance of the the sampling. Eighteen bottled drinking water samples analytical method. The line equation fitted the were purchased from supermarkets in Hefei City, the fluoride concentration reasonably well, and the capital of Anhui Province. The drinking water samples square of the correlation coefficient was 0.998. were filtered through a Millipore cellulose membrane The average recovery of fluoride spiked in double- (0.45 μm) and then stored in polyethylene bottles at a distilled water ranged from 90.5 to 106 %, and low temperature (−4 °C) before analysis.

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