Fluoride Levels in Drinking Water in the Central Province of Saudi Arabia

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1 Fluoride Levels in Drinking Water in the Central Province of Saudi Arabia Abdullah M. AlDosari, BDS, MSD, PhD; Enosakhare S. Akpata, BDS, MDS, FDS, RCPS, FWACS; Nazeer Khan, MSc, PhD; Amjad H. Wyne, BDS, BSc, MDS, FASDC; Abdullah Al-Meheithif, BsChem From the College of Dentistry, King Saud University, and Riyadh Sewage and Water Works, Riyadh, Saudi Arabia. Address reprint requests and correspondence to Dr. Al-Dosari: College of Dentistry, King Saud Univeristy, P.O. Box 60169, Riyadh 11545, Saudi Arabia. Accepted for publication 12 January Received 27 October Background: This study was designed to assess the fluoride levels in drinking water in the Central Province of Saudi Arabia. Materials and Methods: A total of 817 water samples were collected from 260 locations in Central Saudi Arabia. An atomic absorption spectrophotometer [HACH instrument, model DR 3000] was used in the analyses of water samples for fluoride levels. Results: The results showed that fluoride levels vary between 0.00 and 6.20 ppm. About 75% and 6% of the population in Riyadh and Qassim regions, respectively, were exposed to very low fluoride levels ( ppm), while less than 3% of the population in both regions were exposed to fluoride levels ranging from 0.61 to 0.80 ppm. A higher percentage of the population in Qassim than Riyadh region were exposed to high fluoride levels (>0.81 ppm); 28.63% than in Riyadh with 9.24%. Conclusions: The findings of this study can serve as a baseline data for water fluoridation and other dental preventive programs in the area. Ann Saudi Med 2003;23(1-2): AM AlDosari, ES Akpata, N Khan, AH Wyne, A Al-Meheithif, Fluoride Levels in Drinking Water in the Central Province of Saudi Arabia. 2003; 23(1-2): Key Words: Drinking water, fluoride levels, absorption spectrophotometer. Exposure to fluoride in drinking water has been shown to be beneficial for oral and general health, 1-5 especially in relation to dental caries and osteoporosis. In a study carried out in 21 cities in four states in the US, Dean et al. 1 showed that exposure to water containing about 1 ppm fluoride in drinking water reduced caries experience by 50%. However, fluoride levels higher than 1.5 ppm in temperate countries is known to cause dental fluorosis. 2 The earliest study of artificial water fluoridation was carried out in Grand Rapids, USA. 3 The reduction in caries, averaged between 40%-65% in permanent teeth. In a review of 55 fluoridation studies in the literature between 1956 and 1979, Murray and Rugg-Gunn 10 concluded that caries reduction in deciduous teeth was 40%- 50%. Furthermore O'Mullane et al. 11 reported a 40% difference in caries prevalence in deciduous teeth of Irish children residing in fluoride-deficient and fluoridated communities. A symposium devoted to fluoride the International Collaborative Research On Fluoride: Research Needs Workshop was held in May 1999, Maryland, USA. 12 In Saudi Arabia, drinking water is obtained from several sources including desalinated seawater, as well as ground water from wells. 6 More recently, bottled water has been gaining popularity. 7 Kordy and Fonseka 8 have reported that public water supply in Riyadh city was within the optimal range for dental health, while Mohamed and Fattah reported flouride levels of ppm in the drinking water of Riyadh. 9 However, there is little detailed information on the geographical distribution of fluoride levels in drinking water in various parts of the Kingdom. The purpose of this study was, therefore, to determine the fluoride levels in the drinking water in the Central Province of Saudi Arabia with a view to producing a fluoride map of the area. Materials and Methods The water sampling strategy in this study was designed to cover the whole Central Province of Saudi Arabia, especially the populated regions. In this attempt, it was found that the presence of teaching schools (primary, intermediate and secondary) is a good indicator of heavily populated areas. Based on this premise, every city, town, and village with a school was regarded as a potential site for obtaining water samples.

2 The surface area of the Central Province (Riyadh and Qassim) is 4,780,780 km 2, with a population of about 4 million. Maps were obtained from several sources showing the distribution of cities and villages that would be the potential targets for our investigation. The Ministry of Education and the Presidency of Girls Education were contacted in order to determine the distribution of schools in the Central Province of Saudi Arabia. Table 1. s of drinking water in Riyadh region and the level of fluoride concentration. Samples Fluoride concentration (ppm) No. Minimum Maximum Mean Disalinated water 30 (5.5%) government plant 397 (73.1%) private plant 103 (19%) Untreated ground water 13 (2.4%) Total 543 (100%) Table 2. s of drinking water of Qassim region and the level of fluoride concentration. Samples No. Fluoride concentration (ppm) Minimum Maximum Mean government plant 195 (71.2%) private plant 68 (24.8%) Untreated ground water 11 (4%) Total 274 (100%) Table 3. Water collection points. Riyadh Qassim Total Primary school 253 (46.6%) 129 (47.1%) 382 (46.8%) Intermediate school 88 (16.2%) 66 (24.1%) 154 (18.9%) Secondary school 50 (9.2%) 52 (19%) 102 (12.5%) Private plant 96 (17.7%) 16 (5.8%) 112 (13.7%) Government supply 42 (7.7%) 11 (4%) 53 (6.4%) Well water 14 (2.6%) Total 543 (100%) 274 (100%) 817 (100%) Each of the water samples was collected, using 500 ml polythene bottles. The collection of the samples was done during the daytime. The tap water was allowed to run for a few minutes before obtaining the sample. The bottles were first washed three times with the water prior to the collection of about 300 ml of the sample. The water sample was analyzed for fluoride within one week of sample collection, using the atomic absorption spectrophotometer (HACH instrument, model DR 3000). The standardization and validation of the analysis of water samples were done according to the manufacturer's instructions. A standardized solution with a known fluoride concentration (Hach Company, USA) was used for the calibration of the instrument before each set of tests. The statistical significance of the difference between fluoride exposure in Riyadh and Qassim regions was determined, using the chi square test. Results This study identified two main sources of drinking water in the Central Province of Saudi Arabia: ground water and desalinated seawater. About 4% of the sample came from desalinated water, while the remainder was from ground water, some of which was treated by the government or private plants. The sources of drinking water and fluoride concentrations are shown in Tables 1 and 2.

3 A total of 817 water samples were collected from 260 locations, 179 of which were in the Riyadh region and the remaining 81 from the Qassim region. Most of the water samples were collected from water sources located in school premises. Fluoride levels were found to vary between 0.00 and 6.20 ppm. The highest level of 6.20 ppm was recorded at Al-Madnab (Qassim region), while there was virtually no fluoride in the drinking water in Darul Baida (Riyadh region). Generally, fluoride levels were higher in Qassim than in Riyadh region (Table 3 and Figures 1 and 2). The study also showed that the population of Riyadh and Qassim regions exposed to varying fluoride levels in their drinking water (Figure 3). About 75.4% and 6.3% of the population in Riyadh and Qassim regions, respectively, are exposed to very low fluoride levels ( ppm), while less than 3% of the population in both regions are exposed to the fluoride levels ranging from ppm. A higher percentage of the population in Qassim than Riyadh region is exposed to high fluoride levels (>0.81 ppm): 28.63% in Qassim as against 9.24% in Riyadh region. Chi-square test showed this difference to be statistically significant (P<0.05). Discussion Schools were used in this study as an indicator of population distribution. It is government policy to provide free schooling facilities to the entire population in Saudi Arabia. Therefore, the presence of schools would indicate high population concentrations, in contrast to the desert areas that are sparsely populated. The fluoride levels of ppm in drinking water in the present study is higher than the fluoride concentrations of up to 2.5 ppm reported for the Makka area 13 and the Hail region 14 of Saudi Arabia where dental fluorosis is endemic. It is therefore to be expected that dental fluorosis would be prevalent in many areas of the Riyadh and Qassim regions. Investigation into the relationship between fluoride levels in drinking water and severity of dental fluorosis in the Central Province of the Kingdom is, therefore, of interest. Our study shows that over 75% of the population in Riyadh region are exposed to very low fluoride levels of ppm. It has been suggested that the optimal fluoride level in drinking water in communities where ambient temperature is above 27 C should be approximately ppm, 15 while Brouwer et al. 16 recommended an optimal fluoride level of 0.6 ppm for Senegal, a tropical West African country. These recommendations appear to take no cognizance of other sources of fluoride intake such as diet, 17 beverages, 18 infant formula and fluoride tooth pastes. 19 In a recent study in Iran, Zohouri and Rugg-Gunn 20 suggested that the 3-4-year-old-children exposed to ppm fluoride in drinking water ingested 0.03 mg F/kg body weight from their diet per day. In addition, these children ingested mg F/kg body weight per day from fluoride toothpaste, if they brushed their teeth thrice a day. Thus, the fluoride intake from diet and tooth paste ingestion could reach the optimum value of mg F/kg body weight per day recommended by Ophaug et al. 21 and suggested to be the upper limit of daily fluoride intake by Burt. 22 This further underscores the need for comprehensive studies of fluoride exposure in a community before recommending the use of fluoride supplement or determining the appropriate fluoride level in drinking water for a community. Figure 1. Fluoride concentration zones in Riyadh region.

4 Figure 2. Fluoride concentration zones in Qassim region. Figure 3. Population distribution among the different fluoride zones. In the present study, about 12.5% of the population in the Central Province of Saudi Arabia were exposed to fluoride levels above 0.81 ppm. This is excessive for a community in the tropical belt. In 1957, Galagan and Vermillion 23 observed increased water consumption with increase in ambient temperature among California children, implying higher fluoride intake from drinking water as ambient temperature increases. However, in 2001, Sohn et al. 24 found no correlation between daily water intake and ambient temperature among US children. This may be attributed to changing lifestyles as people now spend more time in air-conditioned environment than they did in Drinking water in these communities should be defluoridated or else the communities provided with alternative sources of drinking water with low fluoride concentrations. In determining the appropriate fluoride concentration, a balance has to be struck between the cariostatic effect of the fluoride and its potential to cause dental fluorosis. The findings of this study provide an essential baseline data for future planning of dental preventive programs in the Central Province of Saudi Arabia, especially with regards to water fluoridation. References 1. Dean HT, Arnold FA, Evolve E. Domestic water and dental caries. V. Additional studies of the relation of fluoride in domestic water to dental caries experience in 4425 white children aged years, of 13 cities in 14 states. Public Health Report 1942: World Health Organization. Guidelines for drinking water quality. Vol 1. Recommendations. Geneva: WHO, McClure FJ. Water fluoridation. The search for victory. National Institute for Dental Research. Bethesda, Demos LL, Kazda H, Cicuttini FM, Sinclair MI, Fairley CK. Water fluoridation, osteoporosis, fractures-recent developments. Aust Dent J 2001;46: Kleerekoper M, Schein JR. Comparative safety of bone remodeling agents with a focus on osteoporosis therapies. J Clin

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