|Year : 2020 | Volume
| Issue : 1 | Page : 65-70
Fluoride content of commercial drinking water and carbonated soft drinks available in Southeastern Nigeria: dental and public health implications
FE Ani, EA Akaji, NP Uguru, EM Ndiokwelu
Department of Preventive Dentistry, College of Medicine, University of Nigeria, Enugu Campus, Enugu, Nigeria
|Date of Submission||02-May-2019|
|Date of Acceptance||07-Sep-2019|
|Date of Web Publication||10-Jan-2020|
Dr. E A Akaji
Department of Preventive Dentistry, College of Medicine, University of Nigeria, Enugu Campus, Enugu
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aim: The importance of fluoride in preventing dental diseases cannot be overemphasized. The aim of this study was to determine the fluoride content of commercial bottled water, sachet water and carbonated soft drinks available in Southeastern-Nigeria at the same time, eliciting their dental and public health implications. Method: Determination of fluoride level in water and carbonated drinks was carried out using Colorimetric-SPADNS (Trisodium 2-(4-sulfophenylazo)-1, 8-dihydroxynaphthalene-3, 6-disulfonate) method. This is a simple and rapid technique with high accuracy. 10 brands of bottled water, 10 brands of carbonated soft drinks and 20 brands of sachet water were studied. The experiment for each brand was carried out in duplicates and mean fluoride concentrations generated. Data analysis was done using SPSS version 17. Results: Fluoride contents in mg/L of bottled water brands ranged from 0.0173 ± 0.0019 mg/L to 0.1607 ± 0.0630 mg/L [mean: 0.0442 ± 0.0184 mg/L] and that of sachet water brands was from 0.0131 ± 0.0019 mg/L to 0.1754 ± 0.1344 mg/L. Mean fluoride content of carbonated soft drinks was 0.0228 ± 0.0064 mg/L with one of the brands having as low as 0.0066 ± 0.0028 mg/L fluoride. Conclusion: None of the drinks investigated contained level of fluoride up to standard admissible values suggesting sub-optimal intake. As the suitability of advice on fluoride use in preventing dental abnormalities depends on the individual's total fluoride intake from drinks and other sources, a further study is warranted to relate this total with the baseline decayed missing and filled teeth of the population.
Keywords: Dental caries, fluoride, public health, water
|How to cite this article:|
Ani F E, Akaji E A, Uguru N P, Ndiokwelu E M. Fluoride content of commercial drinking water and carbonated soft drinks available in Southeastern Nigeria: dental and public health implications. Niger J Clin Pract 2020;23:65-70
|How to cite this URL:|
Ani F E, Akaji E A, Uguru N P, Ndiokwelu E M. Fluoride content of commercial drinking water and carbonated soft drinks available in Southeastern Nigeria: dental and public health implications. Niger J Clin Pract [serial online] 2020 [cited 2020 Jan 25];23:65-70. Available from: http://www.njcponline.com/text.asp?2020/23/1/65/275617
| Introduction|| |
Fluoride use in dentistry can be traced back to 1901 when Frederick McKay discovered the Colorado stain. Fluoride can be applied systemically and/or topically on the tooth although maximum benefit appears to be derived from frequent topical application of low fluoride concentrations. This is usually achieved through its intake from water, food and other products with the protective effect on dentition being more beneficial at the pre-eruptive phase of enamel formation Fluoride in water is therefore considered an economic and central component in strategies for preventing dental caries; a disease with major health, economic and social effects worldwide. Water fluoridation at the community level was established through epidemiological studies and is a key achievement of Public health dentistry., However, it thrives where there is uninterrupted piped water supply; this criterion is not readily met in low and middle income countries [LMICs] like Nigeria. Hence packaged water which includes water packaged in disposable plastic bottles and sachets have received strong backing from manufacturers and government to forestall a public health threat of drinking water shortage. It is noteworthy that minerals such as nitrate, calcium, chloride and fluoride can be found as trace elements in packaged water depending on their sources, but significant ones such as fluoride may be absent. Credible reports on addition of fluoride to consumables such as water, carbonated soft drinks, milk, salt, tablets and tooth paste in many countries abound in literature.,, The focus of these studies were geared towards proper analysis of the contents of some products especially drinking water at national and international levels to determine their fluoride level in relation to the World Health Organization (WHO) recommended level of 0.7- 1.5 mgF/L, so that adjustment(s) could be made where necessary to suit the needs of the community.
Thippeswamy et al., (2010) investigated 10 commercially available brands of bottled water and 12 carbonated soft drinks in India and reported the mean fluoride content of bottled water and soft drinks to be 0.20 mgF/L (± 0.19) and 0.22 mgF/L (± 0.05) respectively. Also, a study conducted in Mexico in 2004 found that fluoride concentration of 57 carbonated drinks and 20 samples of bottled water investigated ranged from 0.07 to 1.42 ppm. Aldrees and Al-Manea, (2010) in their work in Saudi-Arabia reported that the mean fluoride content of 12 locally bottled water samples was 0.7 (± 0.009) mg/L with range of 0.5 to 0.83 mg/L, and that of 3 imported brands was 0.67 (± 0.02) mg/L with narrow range of fluoride content (0.65 – 0.69) mg/L. In England, mean fluoride content in bottled water was found to be 0.08 ± 0.08 mg/L, and from Bolgatanga Municipality of Ghana, approximately 40% of the sachet water samples had mean fluoride ion concentrations below the minimum recommended level of 0.50 mg/L; while all the bottled water brands except one had mean fluoride ion concentrations below 0.50 mg/L.
In Nigeria, Akpata et al., (2009) reported that few drinking water sources across geopolitical zones had fluoride concentration exceeding 1.5 part per million (ppm) and that the concentration of fluoride in deep and shallow wells in the North Central zone were higher than other zones in the country (P < 0.05), while various water sources in Southeast Nigeria had mean fluoride content of 0.44 ± 0.66 ppm. Some other studies in Nigeria found fluoride concentrations in ground and surface water ranging from 0.03-0.6 ppm with values of about 2-6 ppm in northern regions of the country.,, A study which focused on 14 springs and 8 streams in Ohafia -Arochukwu area of Southeast found no fluoride in all the streams and only one spring out of the 14 contained fluoride (0.03 ppm). Mean value of 0.63 mg/l fluoride in water was reported for well water in 5 zones in Enugu, a major city in Southeast Nigeria (P < 0.05); and in another city in the region, median values of 0.06 and 0.01 mg/l fluoride in all sachet and bottled water respectively were observed.
The Standard Organization of Nigeria (S.O.N), a regulatory body in Nigeria, harvest guidelines mainly from the International sources like W.H.O and together with National Agency for Food and Drug Administration and Control (NAFDAC) ensure packaged water is safe. With the statistics of about 100 million Nigerians drinking one bottled and/or sachet water per day (Former NAFDAC DG, Dr Paul Orhii, 2013), and Nigeria ranking 4th globally in the volume of soft drink consumption in the year (Euro monitor International Limited, 2016), the demand for these drinks may continue to increase, being driven by population growth. Data on the fluoride content of bottled water, sachet water and carbonated soft drinks available for consumption in the Southeastern Nigeria is limited. These data are essential for all health care providers especially the dental professionals since fluoride use is a primary preventive model in dentistry., The aim of the present study was to determine the fluoride content of commercially available bottled water, sachet water and carbonated soft drinks in the South-East Nigeria with the view to elicit dental and public health implications, and provide data for future research.
| Methods|| |
Study area and protocol
The study was conducted in South East of Nigeria which is one of the six geopolitical zones in the country. Five states namely Abia, Anambra, Ebonyi, Enugu and Imo constitute the zone. All brands of packaged water and carbonated drinks investigated were sold and consumed in the region as at year 2017 when the study was done. Ethical approval for the study was obtained from the College of Medicine Research Ethics Committee, University of Nigeria.
A preliminary investigation to identify common brands of packaged water and carbonated soft drinks available in the 5 states making up the region was carried out to ensure representativeness of the samples and a list was generated. From this list, brands of packaged water and carbonated drinks for this study were selected. We selected brands that appeared in at least 3 out of the 5 states. The number of sachet water brands almost doubled those of bottled water and carbonated drinks in all the 5 states. Ten brands each of bottled water, 10 brands of carbonated soft drinks and 20 brands of sachet water with their registration number, production date and expiry date written on them were selected. These were tagged as B samples, C samples and S samples respectively.
Inclusion criteria were as follows:
- Bottled water, sachet water and carbonated soft drinks registered with regulatory body.
- Bottled water, sachet water and carbonated soft drinks that had well sealed packs.
Exclusion criteria were as follows:
- Unpacked water such as well water, tanker water and rain water.
- Sachet water, bottled water and carbonated drinks not registered with regulating body.
- Poorly sealed and leaking drinks.
Determination of the fluoride content in this study using the SPADNS method
Fluoride content in water and carbonated drink brands were estimated in the laboratory using Colorimetric method. This is a simple and rapid technique with high accuracy and involves using trisodium 2-parasulfophenylazo-2, 7-naphthalenedisulfonic acid trisodium salt (SPADNS). SPADNS reacts with Zirconyl Chloride to give wine-red colored complex, which further reacts with fluoride to give a new complex. The change in concentration of SPADN-ZrOCl2 causes a change in the transmitted light, which is detected by the Colorimeter; this reaction is rapid. Hence the samples can tested within 10 minutes after adding them to the reagent.
Calibration and standard operative procedure observed
Calibration was done using prepared reference solution (S) taken in a 50 mL standard flask and adding 5 mL of a substance with known fluoride content to it. The final volume was then made up to 25 mL. After allowing the reaction to attain equilibrium, the mixture was transferred to a pipette, and the voltmeter reading that is, the concentration of fluoride, CF was recorded. An estimate of the uncertainty in CF was obtained by calculating the 95% confidence limits for the predicted value. Each of the brands was examined in duplicate (2 samples of each brand) and the 2 sets of analysis yielded similar results. One sample (out of the 2) of 10 brands of sachet water and 5 brands of bottled water were randomly selected and re-analyzed to ensure reliability of the method. The samples were counted at the end of the laboratory work to ensure that they were complete in number as part of quality control. Exposure of the body to the reagents was avoided by the use of hand gloves, face mask, laboratory coat and eye goggle. Proper disposal of these personal protective equipment was done after the laboratory procedure.
Data analysis on fluoride content of different brands investigated was done using Statistical Package for Social Sciences software for windows [SPSS version 17, Inc. Chicago IL]. Mean fluoride concentrations for individual brands and subsequently the groups were generated. For the purpose of this study, we used the conversion of 1 part per million (1 ppm) equal to 1 milligram per liter (mg/l) in order to compare findings with similar studies.
| Results|| |
Fluoride contents of bottled water (B)
The result of the 10 brands of bottled water investigated for fluoride content showed the least fluoride level was 0.0173 (± 0.0019) and the highest level was 0.1607 (± 0.0630); mean fluoride level was 0.0442 (± 0.0184) mg/L [Table 1].
Fluoride contents of sachet water samples (S)
The mean fluoride content of the 20 samples of sachet water was 0.028 (± 0.0215) mg/L with a range of 0.0131 (± 0.0019) to 0.1754 (± 0.1344) mg/L. [Table 2] shows the fluoride contents of all the investigated sachet water brands.
Fluoride contents of carbonated soft drinks (C)
The mean fluoride content of the 10 samples of carbonated soft drinks analyzed was 0.0228 (± 0.0064) mg/L. Out of the 10 brands of carbonated soft drinks analyzed, C1 brand had the least amount of fluoride (0.0066 mg/L) while C9 and C10 had the highest amount (0.0373 mg/L) of fluoride. Details are shown in [Table 3].
| Discussion|| |
The long term effects of low or high level of fluoride consumed influence the prevalence of dental caries, dental and/or skeletal fluorosis in such populations. The present study was conducted to determine fluoride level in some of our drinking water and carbonated soft drinks, and relating them with standard reference values. International and national reference values for fluoride levels used here were those of WHO and S.O.N., These values are stipulated to ensure no potential health risks occur due to lack or excess fluoride from these drinks., None of the drinks investigated had its fluoride content stated on the label despite the extant stipulations by S.O.N on labeling of products which cover the physical, organic and inorganic chemical qualities among other functions., Compliance should be reinforced.
This study found lower mean fluoride contents in mg/L in bottled water brands (B series), carbonated soft drinks (C series) and sachet water samples (S series) than the reference values. The values were also lower than those from a range of water sources (not packaged) reported for southeastern Nigeria. The observed trend is quite similar to other reports on unpackaged water within Nigeria, but differed when compared to mean fluoride level in water samples from 50 artisan wells in Enugu. From international spheres, mean fluoride content of bottle water in Fiji, a country in the South Pacific, is slightly higher than that in our study, and the same can be said when compared to reports from England, Mexico and Iraq,, while report from Iran shows very high level of fluoride which may precipitate skeletal fluorosis It is our view that the prevailing situations in these countries as regards intake of fluoride from water and other sources are likely to differ from what obtains in ours. For instance, Ndiokwelu and Zohouri,(2010) in their study on fluoride content of some dentifrices available in Nigeria found that claims on fluoride content of these products by the manufacturers were misleading. Furthermore, carbonated soft drinks investigated in the present study also had low fluoride contents. With the attendant health problems from consumption of soft drinks such as tooth erosion, dental caries, obesity and other effects on general health, low levels of fluoride from soft drinks in this study would support the advice of “drink with caution” used in health promotion and/or disease prevention strategies in line with common risk factor strategy adopted in public health spheres.,,
Fluoride reduces the solubility of enamel in acid by converting hydroxyapatite into less soluble fluoro-hydroxyapatite and promotes the re-mineralization or repair of enamel in areas that have been de-mineralized by acids, preventing dental caries. On the other hand, dental fluorosis results from consumption of excess fluoride during tooth formation. Previous field studies conducted in younger age groups in this region about a decade ago reported low prevalence of dental caries., A higher prevalence of 68.2% was recorded about 5 years later, it was however conducted amongst mixed populations in a key tertiary health institution which serves as a referral centre for patients in the region and neighboring states. To ensure that this public health condition is properly checked, primary preventive models such as use of fluoride need to be rightly positioned. Hence, low values of fluoride in the present study which suggest sub-optimal fluoride intake triggers the need for an all-encompassing research in defined populations featuring fluoride intake from other sources such as foods that are readily consumed in our environment, frequency of intake of water depending on weather conditions, use of other fluoridated products such as toothpaste, and baseline decayed missing and filled teeth (DMFT). That way, prevalence of dental caries in the region can be related with the total fluoride ingested, and caries free individuals would be identified. Those who need fluoride supplementation at individual and community basis especially children can be targeted and attended to. A limitation of the present study is that the above listed parameters were not measured being outside its scope. Barring this, findings from our investigation provide preliminary information on fluoride levels of available drinks in Southeastern Nigeria, and would be useful in accomplishing the recommended study on a wider scale.
In conclusion, all selected brands of sachet, bottled water and carbonated drinks had mean fluoride concentrations much lower than the standard admissible values. A balanced advice on fluoride use in preventing dental abnormalities depends on an individual's total ingestion of fluoride from water, food and other sources. There is therefore need for further study relating the consumption of these drinks, fluoride-containing foods, other products with fluoride, and frequency of their intake with the baseline DMFT of the population. Also, regulating bodies should increase their surveillance over these drinks to ensure strict adherence to international standards.
We acknowledge the assistance of Mr Nnaemeka Asogwa in coordinating the laboratory procedures.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]