FLUORIDE LEVELS IN DIFFERENT DRINKING WATER SOURCES IN BANGLADESH. AKM Fazlul Hoque, am Khaliquzzaman,b M D Hossain,c A H Khand Dhaka, Bangladesh

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1 38 Fluoride Vol. 36 No Research Report FLUORIDE LEVELS IN DIFFERENT DRINKING WATER SOURCES IN BANGLADESH AKM Fazlul Hoque, am Khaliquzzaman,b M D Hossain,c A H Khand Dhaka, Bangladesh Summary: The fluoride levels in 304 water samples from different sources in Bangladesh were determined using the proton induced gamma emission (PIGE) method. Concentrations vary from 0.02 to 2.32 mg/l with a mean of 0.43 ± 0.40 mg/l In tube well water the concentrations range from 0.02 to 2.32 mg/l for 163 samples with a mean of 0.56 ± 0.48 mg/l. Surface waters contain the lowest amount of fluoride with a mean of 0.14 ± 0.10 mg/l for 23 samples. In rain water the mean fluoride content is 0.26 ± 0.13 mg/l, slightly higher than in surface water. The concentration of fluoride in 102 city water supplies ranges from 0.03 to 1.10 mg/l with the mean of 0.33 ± 0.21 mg/l These results indicate that the fluoride level in groundwater is, in general, lower than the maximum official permissible limit of 1 mg/l in drinking water set for Bangladesh. Keywords: Bangladesh water fluoride, Fluoride in water, Proton induced gamma emission, Rainwater, Surface water, Tube well water. INTRODUCTION Excessive fluoride intake causes fluorosis, cancer, arthritis, and other diseases.1-5 It also affects human intelligence, especially in children, who are most susceptible to early fluoride toxicity. 25 Chronic fluoride intoxication (fluorosis) occurs not only in human but also in domestic animals, such as, cattle, buffaloes, sheep, and goats. 6 Contamination of water resources with fluoride beyond acceptable limits is a health problem in many areas of South Asia and other regions of the world because the earth's crust in those regions has fluoride bearing minerals. 7-8 In some regions of India, water contains fluoride up to 38 mg/l, which is exceedingly high compared to the maximum permissible limit (MPL) of 1 mg/l set for India. 9 The fluoride content of groundwater in India, especially in the States bordering Bangladesh, suggests that an investigation of the situation in Bangladesh is required. The geology of Bangladesh is quite similar to some bordering areas of India. It is therefore possible that the groundwater of Bangladesh may also have been affected by natural fluoride. The present study was therefore undertaken to investigate the natural fluoride levels in Bangladesh water sources. The proton induced gamma-ray emission (PIGE) method was employed for the measurement of fluoride concentration in water samples collected afor Correspondence: Dr AKM Fazlul Hoque, Accelerator Facilities Division, Atomic Energy Centre, PO Box 164, Dhaka 1000, Bangladesh. fhoque@bttb.netbd bconsultant, Environment group, World Bank Dhaka Office, 3A Paribagh, Dhaka, Ban~ladesh. cphysics Department, Jahangirnagar University, Savar, Dhaka, Bangladesh. Department of Chemistry, Dhaka University, Dhaka 1000, Bangladesh.

2 Fluoride levels in Bangladesh drinking water sources 39 from both rural and urban areas of Bangladesh. PIGE analysis is based on the detection of prompt gamma rays emitted from the excited fluorine nuclei following the nuclear reactions (p, y), (p, p' y), (p, a y), and (p, n y) induced by protons. The energy of the gamma ray identifies the isotope, and the intensity measures its concentration in the sample. PIGE is a sensitive andreliable method for fluoride analysis in water samples. 10 -n An important advantage of PIGE is its ability to determine a number of low Z elements simultaneously, especially lithium, boron, fluorine, etc., in health-related environmental samples. MATERIALS AND METHODS Sample collection: Of the total 304 water samples, 163 were from tube wells, 102 from city supplies; 23 were from ponds, lakes, and fountains in rural and urban areas of Bangladesh, and 16 were rain water samples. Samples of municipal water supplies were collected from the 14 major cities listed in Table 2, Barisal, Bogra, Chittagong, etc. Tube well water samples were collected both from the rural and urban areas of 19 districts given in Table 3. Surface water samples were collected from the ponds, lakes, fountains, and rivers of Dhaka, Chittagong, Comilla, Mymensingh and Sylhet areas. Rainwater samples were collected in two locations of Dhaka city during the months of September and October, A 500 ml sample of each water source was collected in a pre-cleaned plastic bottle. The bottles were thoroughly washed and rinsed with demineralized water prior to collecting the samples. Sample preparation: Samples were prepared for fluoride determination by evaporation of 200 ml of water sample together with I 00 mg of ashless cellulose powder followed by grinding and pelletizing for irradiation as described previously. 11 Concentration calibration: The concentration calibration curve was obtained by using a CaC0 3 matrix mixed with AnalaR grade NaF concentrations ranging from 10 to 500 mglkg as reported previously.u The number of gamma rays emitted from the nuclear reaction 19 F(p, p' y) 19 F per unit charge was used to construct the curve. The calibration curve was used to determine fluoride concentrations in water residues on a dry weight basis (mglkg). These concentration data were then converted to mg F!L of water samples with respect to 200 ml of each sample. Method of analysis: The measurements were conducted with a proton beam energy of 2. 9 MeV obtained from the 3 MV Van de Graaff accelerator at the Atomic Energy Centre, Dhaka (AECD) using the external beam PIGE method. The experimental set up is described elsewhere. 10 -ll Estimated proton energy on the target after absorption at the exit window and the air between the window and the sample is 2.3 MeV. Each sample was irradiated

3 40 Fazlul Hoque, Khaliquzzaman, Hossain, Khan for a preset charge of 5-20!JC with a beam current of 15 na. The characteristic y-rays emitted following the reaction 19 F(p, p' y) 19 F were detected with a high purity germanium (HPGe) detector having a resolution of 1.75 kev at 1332 kev y-rays. Standard NIM electronics and a 4095 channels pulse height analyzer were used for data acquisition and analysis. The gamma ray spectrum was analyzed using commercially available y-ray unfolding software obtained from APTEC Nuclear Inc. USA. RESULTS AND DISCUSSION Fluoride concentrations in 304 water samples from different sources ranges from 0.02 mg/l to 2.32 mg!l with a mean of 0.43 ± 0.40 mg!l. The mean fluoride concentrations in water samples from different sources are given in Table 1. Note that tube well water contains the highest amount of fluoride. The mean concentration in 163 tube well water samples is 0.56 ± 0.48 mg!l with a range of 0.02 to 2.32 mg!l. Table 1. Distribution of fluoride in different sources of water in Bangladesh Sl City No. of Fluoride concentration No Samples (mg/l) Range Mean 1 Tube well ± City supply ± Surface ± Rain ± 0.13 The fluoride concentration in 102 water samples from 14 major cities is in the range of mg/l with a mean of0.33 ± 0.21 mg/l. Surface water contains the lowest amount of fluoride with a mean of 0.14 ± 0.10 mg/l for 23 samples studied. The concentration of fluoride in these surface waters ranges from 0.04 to 0.40 mg/l. The mean fluoride content in 16 rain water samples is 0.26 ± 0.13 mg/l with a range of 0.07 to 0.48 mg/l, which is higher than in surface water. This may be due to the presence of fluorine in atmospheric air. Some industries, such as aluminum smelting, fertilizer, chemical, steel, and plastic use fluoride-containing substances, which could pollute the environment with fluoride dust, gas, or fumes. Smoke, dust, and gases from coal burning industries also contribute to the environmental fluoride pollution. Thus rain water can also be contaminated with fluoride.

4 Fluoride levels in Bangladesh drinking water sources 41 Ordinarily, groundwater is chlorinated when dispensed into municipal water systems for drinking and other purposes. These chlorinated waters contain lower amounts of fluoride. The means and ranges of fluoride distribution in city water supplies are given in Table 2. It is clear from the results that fluoride levels in all city supplies are below the maximum permissible limit (MPL) of 1 mg/l set for drinking water in Bangladesh. 12 It is also observed that about 80% of the water samples analyzed contain fluoride less than 0.5 mg/l. As seen in Table 2, the water supplies of all the cities except Barisal, Dinajpur, and Rajshahi contain a much lower amount of fluoride. Table 2. Concentration of fluoride in 14 city water supplies of Bangladesh Sl City No.of Fluoride concentration No Samples (mg/l) Range Mean 1 Barisal ± Bogra ± Chitta gong ± Camilla ± Dhaka ± Dinajpur ± Gazipur ± Jessore ± Kustia ± Mymensingh ± Rang pur ± Rajshahi ± Sylhet ± Tangail ± 0.14 Tube well water is the main source of drinking water in rural areas of Bangladesh. Water from open wells, ponds, etc. is also widely used for drinking and cooking purposes in some parts of the country. The depth of the tube wells in Bangladesh, in general, is in the range of 15 to 100 m. The regional ranges and mean fluoride concentrations in tube well water are shown in Table 3. Wide variation in fluoride concentrations in tube well water samples is observed, and the mean fluoride concentrations in tube well waters of Bogra, Chittagong, Gazipur, Jamalpur, Kishoregong, Mymensingh, Sy lhet, and Tangail regions are much lower than the MPL of 1 mg/l. On the other hand, the tube well water of Barisal, Faridpur, Jessore, Khulna, and Rajshahi regions contain higher levels fluoride than any of the other regwns. Fluoride 36 (1) 2003

5 42 Fazlul Hoque, Khaliquzzaman, Hossain, Khan Table 3. Regional distribution of fluoride in tube well water in Bangladesh Sl No City No.of Fluoride concentration Samples (mg/l) Range Mean 1 Bansal ± Bogra ± Chittagong ± Camilla ± Dhaka ± Dinajpur ± Faridpur ± Gazipur ± Jamal pur ± Jessore ± Khulna ± Kishoregong ± Kustia ± Mymensingh ± Pabna ± Rajshahi ± Rang pur ± Sylhet ± Tangail ± 0.16 The pie distribution of samples of different fluoride concentrations is shown in the Figure. Note that the fluoride concentration in 61% of samples is less than 0.5 mg/l. In 84% of the samples it is lower than the maximum permissible limit (MPL) of 1 mg/l set for Bangladesh drinking water. 12 In only 16% of the samples are there higher amounts of fluoride than the MPL. m < o.5 Ell D D > 1.5 Figure. Percentages of water samples in Bangladesh with different fluoride concentration ranges (mg/l)

6 Fluoride levels in Bangladesh drinking water sources 43 This study suggests that, in general, the fluoride concentration in ground water of Bangladesh is low. But in some rural areas of Bangladesh the fluoride concentration in water is higher than the MPL. Fluoride in water may be a problem in rural areas where the drinking water is drawn from any available sources such as a pond, open well, tube well, or a shallow tube well with a hand pump, in which the fluoride concentration may exceed the MPL. Awareness of the quality of drinking water is also lacking among the rural population, which usually has no 'provider' of drinking water. To evaluate the impact of fluoride in drinking water in rural areas where the fluoride concentration is higher than the maximum permissible level of 1 mg/l, the amount of fluoride in food, vegetables, chewing sticks, and dental products used in the locality needs to be measured. To this end the total daily fluoride intake by people living in these localities needs to be determined. A research program in this regard has been initiated. ACKNOWLEDGMENT The authors wish to acknowledge the cooperation of colleagues at the Accelerator Facilities Division, and the Chemistry Division of AECD. The partial financial support received from the Ministry of Science and Information & Communication Technology, Government of the People's Republic of Bangladesh, under the special grant program for carrying out this research is gratefully acknowledged. REFERENCES 1 Yiamouyiannis J. Fluoride the Aging Factor, 3rd ed. Delaware (Ohio, USA): Health Action Press; Waldbott GL. The preskeletal phase of chronic fluoride intoxication. Fluoride 1998;31 ( 1 ): Maurer JK, Cheng MC, Boysen BG, Anderson RI. Two year carcinogenicity study of sodium fluoride in rats. J Nat Cancer lnst 1990;82: Cohn PD. An Epidemiological Report on Drinking Water Fluoridation and Osteosarcoma in Young Males. New Jersey Department of Health, Environmental Health Service, Trenton, NJ. Nov. 8, Li XS, Zhi JL, Gao RO. Effect of fluoride exposure on intelligence in children. Fluoride 1995 ;28( 4 ): Choubisa SL. Fluorosis in some tribal villages of Udaipur district (Rajasthan). J Environ Bioi 1998;19: Susheela AK. Epidemiology and Control of Fluorosis in India. Fluoride 1985;18(2): Karthikeyan G, Anitha Pius, Apparao BV. Contribution of fluoride in water and food to the prevalence of fluorosis in areas of Tamil Nadu in South India. Fluoride 1996;29(3): Susheela AK. Dark side of fluoride. The Daily Star 1999 February 20; Features,l6 (col. 5). Fluoride 36 (1) 2003

7 44 Fazlul Hoque, Khaliquzzaman, Hossain, Khan 10 Fazlul Hoque AKM. Analytical Application of Charged Particle Induced Nuclear Reactions for Low Mass Elemental Analysis. PhD Dissertation, Physics Department, Jahangirnagar University, December Fazlul Hoque AKM, Khaliquzzaman M, Hossain MD, Khan AH. Determination of fluoride in water residues by proton induced gamma emission measurements. Fluoride 2002;35(3): Drinking water quality, Bangladesh. Bangladesh Gazette addition. August 28, Published by the International Society for Fluoride Research Editorial Office: 727 Brighton Road, Ocean View, Dunedin 9051, New Zealand