PREVENTION OF DENTAL FLUOROSIS BY HARVESTING RAINWATER IN SRI LANKA

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1 29 29 PREVENTION OF DENTAL FLUOROSIS BY HARVESTING RAINWATER IN SRI LANKA Roshnal Perera, a Newell Johnson, b Udaya Usgodaarachchi, c Thanuja Ariyananda, d Inginimitiya village, North Western Province, Sri Lanka SUMMARY: A cross-sectional survey on the use of harvested rainwater as a source of low fluoride (F) drinking water was conducted in 2005 in the rural village of Inginimitiya in the dry zone of Sri Lanka. This village area was previously afflicted with endemic dental fluorosis from groundwater F. In 1995, the majority of the village households began using 5,000-liter rainwater collection tanks for drinking (95%) and cooking (91%). F analysis revealed a highly significant (p<0.001) and clinically meaningful difference between the mean F levels in the groundwater sources (1.27±0.54, range ppm) and collected rainwater (0.272±0.134, range ppm). Collected rainwater with a low F content has widespread community acceptance and appears to be effective in preventing dental fluorosis. Keywords: Dental fluorosis; Groundwater fluoride; Rainwater harvesting; Sri Lanka rainwater. INTRODUCTION Apart from air-contaminated areas, rainwater usually contains only very small amounts of dissolved minerals. 1 Moreover, collected rainwater is capable of being stored in a safe, drinkable state for more than six months 2 and therefore has the potential for being a potable water source low in fluoride (F). 3 In the dry zone of Sri Lanka, which has a bi-modal rainfall pattern with an average annual rainfall of 1861 mm and a dry period spanning up to 5 months, 4.5 there has been a revival of harvesting rainwater since Sponsored by the World Bank and the Government of Sri Lanka, a Community Water Supply and Sanitation project has provided 5,000-liter rainwater collection tanks to families in F-endemic areas. In some parts of the world, defluoridation of water by additive and adsorptive methods are fairly effective 7,8 In Sri Lanka, however, defluoridation with bone charcoal has been unsuccessfully piloted. 9 The research reported here was conducted to assess the feasibility and effects of using harvested rainwater as a source of low F drinking water in a Sri Lankan community that had endemic dental fluorosis. MATERIALS AND METHODS Initially in this study, the familiar H. Trendley Dean Classification and Index of Dental Fluorosis was recorded for the year-old children in all 11 schools of the Inginimitiya village area of Sri Lanka. 10,11 Secondly, a questionnaire and a checklist found the pattern and practices of rainwater use from all 89 eligible households. Thirdly, twin samples of water from 27 randomly selected tanks and the owner s prior groundwater sources were collected for analysis of F levels using the zirconium (Zr) ion and 2-(pa For correspondence: Roshnal Perera, PhD Candidate, Griffith Health Institute and School of Dentistry, Griffith University, Queensland, Australia, and No. 964, Mahabage Road, Ragama, Sri Lanka. r.perera@griffith.edu.au; b Professor Newell Johnson, Griffith Health Institute, Griffith University, Queensland, Australia; c Dr Udaya Usgodaarachchi, Public Health Specialist, Oral Health Unit, Family Health Bureau, Colombo, Sri Lanka; d Dr Thanuja Ariyananda, Director, Rainwater Harvesting Forum, Sri Lanka.

2 30 30 sulfophenylazol)-1,8-dihydroxy-3,6-naphthalenedisulfonate (SPADNS) method. 12 Ethical approval was obtained from the Ethics Review Committee of Faculty of Medicine, University of Colombo (no. EC/05/052). RESULTS AND DISCUSSION Dry zone and water: Traditionally, people in the dry zone of Sri Lanka obtained water from reservoirs and shallow wells. However, increased water consumption has depleted surface water sources, leaving deep water wells (tube wells) as the only alternative. 13 These wells are usually 50-m deep, at which F levels are significant, 14 thereby increasing the risk of dental fluorosis from their use as drinking water. 13 Although reticulated low-f piped water is available in some parts of the region, because of the large area involved and the nature of the terrain, laying pipes to most houses, which are widely separated, is not economically viable. Rainwater harvesting is therefore popular in such areas. Prevalence of dental fluorosis: As seen in Table 1, nearly 80% of the 15-year-old children, born in 1990, five years before revival of the rainwater harvesting program began in 1995, had fluorotic incisor and canine teeth, mostly in the milder forms. From the data in Table 1, The Community Fluorosis Index (CFI), calculated by Dean s method, was 0.90 (332/368), which is more than twice the 0.4 level Dean thought was desirable not to be exceeded. Previous research conducted in Sri Lanka has shown similar prevalences. 13,14,15 A CFI as high as 1.69 was found by Tennakoon in the adjacent district of Anuradhapura. 13 Ta ble 1. Degree of dental fluorosis am ong 15-year-old schoolchildren in Inginimitiya village according to Dean s classification of dental fluorosis a Degree of dental fluorosis No. (%) None 72 (19.6) Questionable 112 (30.4) Very mild 108 (29.3) Mild 60 (16.3) Moderate 16 (4.4) Severe 0 (0) Total 368 (100) a Only the incisors and canine teeth were examined. The Dean Community Fluorosis Index (CFI) calculates to Quality and usage of collected rainwater: According to the survey, almost all users maintained their tanks in conformity with the stipulated collection and storage guidelines: cleaning the roof, cleaning the tank and gutter system prior to water collection and sealing the tank after collecting the water (Table 2). Various uses of the collected rainwater are shown in Table 3. However, only 19% chlorinated and only 3% boiled the water before drinking it. According to Ariyananda, 9 the initial poor acceptability of rainwater is due to low mineral

3 31 31 content affecting taste, ominous perceptions of rainwater, and contaminants giving it a bad odour. However, the poor quality of groundwater from deep wells, has led to a greater acceptance of rainwater (Table 2). Table 2. Perception of users about collected rainwater vs. their previous ground water sources Parameter (No. surveyed) Rainwater Good No. (%) Ground water Good No. (%) p value* Taste acceptable (89) 79 (89) 24 (27) <0.001 No bad odour (89) 81 (91) 77 (87) <0.01 No colour (89) 77 (87) 43 (48) <0.001 Overall acceptability (89) 82 (92) 64 (72) <0.001 *p value was calculated using t test. Table 3. Usage and quality indicators of collected rainwater Variable (No. surveyed) No. (%) Type of use Use for drinking (89) 84 (95) Use for cooking (89) 81 (91) Drinking and cooking only (89) 23 (26) Use for washing (89) 58 (65) Other uses (89) 56 (63) Conformity to guidelines Filter satisfactory (89) 86 (97) Cleaning roof/gutter satisfactory (89) 89 (100) No contaminants (89) 84 (89) Purification methods used for rainwater Boil before use (89) 3 (3) Chlorination before use (89) 17(19) Fluoride levels in water: As seen in Table 4, the mean F level in the collected rainwater samples was significantly lower than the mean level in the groundwater sources. Table 4. Comparison of fluoride levels in the collected rainwater and groundwater Water source a No. of samples Mean Range Rain water ± Ground water ± a Compared using t test: p value <0.001

4 32 32 The F level in the collected rainwater was also well below the clinical cut-off level of 0.8 ppm, as suggested by Warnakulasuriya. 16 The groundwater fluoride levels are in agreement with findings of other researchers. 14 Adequacy of collected rainwater: Because Sri Lanka has a bimodal pattern of rainfall, harvesting rainwater for drinking and cooking is rational. 17 As expected, the average period of use for the collected water was greater among families using water only for drinking and cooking (Table 5). Therefore, if the collected water is consumed only for drinking and cooking and is handled properly, it should be adequate to survive the rainless period. Table 5. The duration of use for collected rainwater Use (No.) Duration of use (months) Drinking and cooking only (23) 4.3±0.4 Other combinations (66) 2.4±0.9 CONCLUSION The majority of the Inginimitiya village population now uses stored rainwater as their major source for drinking water. This water has comparatively low levels of F, implying that such use would assist in preventing dental fluorosis among children in the area. Prospective studies should be conducted to assess the utility, in terms of costs, compliance, and effectiveness, of this strategy in preventing dental fluorosis in similar communities, of which there are many in Sri Lanka. REFERENCES 1 Sazakli E, Alexopoulos A, Leotsinidis M. Rainwater harvesting, quality assessment and utilization in Kefalonia Island, Greece. Water Res 2007;41: International Environmental Technology Centre; United Nations Environment Programme, Division of Technology, Industry and Economics. Rainwater Harvesting & Utilization: an environmentally sound approach for sustainable urban water management: An Introductory Guide for Decision-Makers. Osaka (Japan): ITC; Available from: van den Hoop MAGT, Cleven RFMJ, van Staden JJ, Neele J. Analysis of fluoride in rain water. Comparison of capillary electrophoresis with ion chromatography and ion-selective electrode potentiometry. J Chromatogr 1996;739: Chandrapala L. Comparison of areal precipitation of Sri Lanka on district basis during the periods and Central Environmental Authority. Proceedings of the National Symposium on Climate Change; 1997 March; Colombo, Sri Lanka. 5 Briöt OJ, Vounatsou P, Amerasinghe PH. Malaria seasonality and rainfall seasonality in Sri Lanka are correlated in space. Geospat Health 2008;2(2): Ariyananda T. Quality of collected rainwater from Sri Lanka [paper submitted for 26th WEDC Conference in Dhaka, Bangladesh, 2001, by Ariyananda T, Lanka Rain Water Harvesting Forum] [cited 2010 Jul 10]. Available from: pubs/papers/ Then click on link: qocrwfsl2001.pdf. 7 Pearce EIF, Larsen MJ. Defluoridation of drinking water by co-precipitation with apatite [abstract]. Fluoride 1995;28(1):41 8 Maruthamuthu M, Sivasamy A. Defluoridation by zeolites and apophyllite. Fluoride 1994;27(2): Phantumvanit P, LeGeros RZ. Characteristics of bone char related to efficacy of fluoride removal from highly-fluoridated water. Fluoride 1997;30(4): Kumar JV, Swango PA, Opima PA, Green EL. Dean's fluorosis index: an assessment of examiner reliability. J Public Health Dent 2000;60(1):57-9.

5 World Health Organization. Oral Health Surveys Basic Methods. 4th ed. Geneva, Switzerland: WHO; Arancibia JA, Rullo A, Olivieri AC, Nezio SDi, Pistonesi M, Lista A, et al. Fast spectrophotometric determination of fluoride in ground waters by flow injection using partial least-squares calibration. Analytica Chimica Acta, 2004;512: Tennakoon TMMH. Dental Fluorosis in Anuradhapura District, Sri Lanka. In: Dahi E, editor in collaboration with Rajchagool S. Proceedings of the 4 th International Workshop on Fluorosis Prevention and Defluoridation of Water; 2004 Mar 2-6; Colombo, Sri Lanka. Chiang Mai, Thailand: ISFR, EnDeCo and ICOH; [cited 2010 Aug 25]; Available from: 14 van der Hoek W, Ekanayake L, Rajasooriyar L, Karunaratne R. Source of drinking water and other risk factors for dental fluorosis in Sri Lanka. Int J Environ Health Res 2003; 13(3): Abayaratna S, Krishnarasa K. National Oral Health Survey Report Colombo, Sri Lanka: Ministry of Health; Warnakulasuriya KA, Balasuriya P, Perera PA, Peiris LC. Determining optimal levels of fluoride in drinking water for hot, dry climates a case study in Sri Lanka. Community Dent Oral Epidemiol 1992;20(6): Ariyananda T. Health risk due to drinking domestic roof water harvested [Paper presented at XI IRCSA conference August 2003, Mexico, by Ariyananda T, Lanka Rain Water Harvesting Forum] [cited 2010 Aug 25]; Available from: pubs/papers/then click on: hrdtddrfh2003.pdf. Copyright 2013 The International Society for Fluoride Research Inc Editorial Office: 727 Brighton Road, Ocean View, Dunedin 9035, New Zealand.

Strategy for Fluorosis Mitigation Program in India

4 th International Workshop on Fluorosis Prevention and Defluoridation of Water 129 Strategy for Fluorosis Mitigation Program in India A K Susheela * India SUMMARY: An innovative approach for fluorosis