Download Fluoride content of bottled water Vs

Fluoride Content of Bottled Water vs. Tap Water in Tehran, Iran
Masoumeh Moslemi*, Mina Mahdian**, Soraya Karimi**, Mohammad Mostafa Shadkar***, Zahra Shadkar****1
Abstract:
Introduction
The aim of this study was to evaluate the fluoride content of bottled drinking waters and
report on the accuracy of the fluoride content of public water system available in
Tehran.
Materials and Methods
Eight selected commercial different brands of locally produced mineral of bottled water
were purchased from local stores (Three bottles of each brand were purchased).
Samples of tap water were collected in sterile containers from the 4 local public water
system (ten samples of each region) was considered for fluoride content evaluation.
Both groups of samples were collected in five equal containers in two different seasons.
Fluoride levels were determined by an ion-selective electrode method (Orion, 96-09-00,
MA, USA). All samples were number coded so that the investigators were blinded to the
type of water contained in the samples. In order to compare the fluoride content of tap
water with bottled water in two different seasons, the data were analyzed using two way
ANOVA test. Furthermore to compare the fluoride content of three different brands of
mineral bottled water, we considered the one way ANOVA test and finally one sample tTest was employed to compare the label and laboratory values.
1
*Associate professor, Dept of Pediatric dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran
** Dentist, Shahid Beheshti University of Medical Sciences, Tehran, Iran
***Under graduate student, Shahid Beheshti University of Medical Sciences, Tehran, Iran
****Under graduate student, Shahid Beheshti International University of Medical Sciences, Tehran, Iran
Results
The highest concentration of fluoride was found in Dessani mineral water (0.409 ppm)
with a pH of 6.67 during hot season. There was significant difference between the mean
fluoride level of tap water (0.229± 0.079) and bottled mineral water (0.111±0.122)
[P<0.001]. The displayed Fluoride concentration on the labels was significantly above
the levels measured in this study (P<0.001).
Conclusion
The mean fluoride level of both mineral bottled water and tap water in Tehran is
considerably lower than WHO a standard which necessitates the surveillance of official
organizations over bottled water industry and the water plant supplies throughout the
country.
Key words
Bottled water, Fluoride content, Tap water
Introduction:
Fluoride is considered as one of the most valuable sources of oral health promotion
over the past fifty years. The primary mode of action of fluoride in reducing dental caries
is that it promotes remineralization and inhibits demineralization of tooth structure, thus
greater emphasis should be devoted to the post-eruptive absorption of fluoride
throughout one’s life. Adjustment of daily fluoride intake is of great importance i.e. low
levels of fluoride is not regarded as effective in preventing dental caries whereas higher
concentrations of fluoride will lead to dental fluorosis. Hence, it is crucial for the dentist
to evaluate the amount of fluoride intake among children [1]. Water fluoridation is
considered as one of the most efficient means of reducing dental caries on a public
health level and has its greatest influence on socially disadvantaged children with high
incidence of tooth decay [2,3,4].One of the most common trends in recent years is the
replacement of purified tap water with bottled water [5]. Different studies have reported
inconsistency between the actual fluoride content of still bottled water and the amounts
mentioned on their labels [6, 7, and 8].
Some countries have close surveillance on the manufacturers of bottled water regarding
the regulation of different elements such as calcium, iron and silver however there is
little evidence supporting the accuracy of the fluoride content of tap water and bottled
water in Iran [9].Hence this study was designed to assess the fluoride content of public
tap water in Tehran and to compare it with the available brands of bottled water in the
market.
Materials and methods:
Eight different brands of locally produced mineral bottled water were randomly selected
and considered for fluoride content evaluation. Samples of tap water were also collected
from different residential areas of Tehran representing the four main water plants i.e.
Karaj dam, Latian dam, Lar dam and Taleghan dam. Both groups of samples were
collected in five equal containers in two different seasons. All samples were stored
sealed in their original containers until the fluoride analysis was made. After shaking the
bottle of water, a 1-mL samplewas taken and mixed with 0.1 mL of Total Ionic Strength
Adjusting Buffer III (TISAB II, Orion, MA, USA). The fluoride concentrations of all 125
samples were determined, in duplicate, using a Fluoride Ion Selective Electrode (model
96-09, ATI Orion) in conjunction with an ISE Meter (Model 720A, ATI Orion). Fluoride
standards ranging from 0.001 to 10.00 mg L-1 fluoride were used to calibrate the
measurement. The pH of the water samples was also measured using a pH-meter
(Model 240, Corning). 10 samples were randomly selected and re-analysed to assess
the reliability of the method. All samples were number coded so that the investigators
were blinded to the type of water contained in the samples.
In order to compare the fluoride content of tap water with bottled water in two different
seasons, the data were analyzed using two ways ANOVA test. Furthermore to compare
the fluoride content of three different brands of mineral bottled water, we considered the
one way ANOVA test and finally one sample t-Test was employed to compare the label
and laboratory values. All measurements were analyzed via. SPSS (Statistical Package
for Social Sciences, version 15) was used to derive descriptive data.
Results:
Table 1 demonstrates the mean fluoride content and the Ph values of the given
samples. The least fluoride concentration collected over cold season was derived from
Damash Mineral water (0.009 ppm) with a pH of 7.54 and the highest concentration was
found in Dessani mineral water (0.409 ppm) with a pH of 6.67. Among the samples
collected during winter time, again Damash (0.002 ppm) and Dessani (0.387ppm) had
the least and most Fluoride content respectively. The results also indicate that of the
three water plants supplying the tap drinking water of Tehran, Karaj dam contains the
lowest concentration of Fluoride during cold season (0.129 ppm) and Lar dam contains
the highest concentration of Fluoride during warm season (0.358 ppm).
Table 1: Fluoride concentrations of 8 brands of bottled waters and tap water from three water plants and pH values
Type of water
Summer
F Concentration
Winter
pH
(PPM)
F
Labeled
pH
content
Concentration
(PPM)
Mineral
Kouhrang
0.210
7.55
0.190
7.60
0.23
bottled water
Vata
0.090
7.30
0.057
7.24
0.11
brands
Pure life
0.068
8.00
0.045
8.02
0.07
Dessani
0.409
6.67
0.387
6.54
0.6-1.1
Zamzam
0.040
6.09
0.028
6.70
Not labeled
Bisheh
0.037
7.47
0.022
7.39
0.07
Dmavand
0.107
6.66
0.083
6.53
0,2
Damash
0.009
7.54
0.002
7.59
0.2>
Karaj dam
0.182
7.58
0.129
7.43
Tap water
Latian
0.208
7.54
0.194
7.44
0.358
7.62
0.305
7.58
dam
Lar dam
The two-way ANOVA test results failed to show significant difference between the
Fluoride concentration of water samples collected over summer and winter ( P= 0.222).
However, there was significant difference between the Fluoride content of mineral
bottled water and tap water (P<0.001) [table 2].
Table 2: Fluoride concentration of mineral and tap water samples by seasonal difference
Season/ Type of
Number
water
Summer
Mean F Level
(±SD)
Mineral
40
0.101±0.122
Tap W
15
0.209±0.075
Total
55
0.131±0.120
Mineral
40
0.121±0.124
Tap W
15
0.249±0.08
Total
55
0.156±0.127
Mineral
80
0.111±0.122
Tap W
30
0.229± 0.079
Total
110
0.143± 0.124
W
Winter
W
Total
W
Further analysis comparing the Fluoride concentration among three brands of mineral
bottled water chosen randomly (i.e. Kouhrang, Vata, Purelife), documented significant
difference between the three brands (P<0.001). Among these, Kouhrang (Mean
Fluoride 0.196± 0.004) and Purelife (Mean Fluoride 0.052± 0.001) contained the highest
and lowest Fluoride level respectively (Table 3).
Table3: Fluoride level of mineral bottled water
Brand
Number
Mean F Level (±SD)
pH
Labeled
content
Kouhrang
5
0.196± 0.004
7.59
0.23
Vata
5
0.083± 0.001
7.31
0.11
Purelife
5
0.052± 0.001
7.90
0.07
Regarding the accuracy assessment of the labels of the three chosen brands, our
results indicated that the displayed Fluoride concentration was significantly above the
levels measures in this study (P<0.001).
Discussion:
Fluoridated water is generally regarded as a safe and accessible oral health measure to
prevent dental caries among all groups of the society [10].
In view of the fact that the fluoride content of tap water is reported inconsistently
throughout the country and there is an overgrowing trend toward the consumption of
mineral bottled water, it is essential to control the concentration of different elements
including fluoride in these products.
In order to measure the fluoride concentration, we employed the Ion Selective Electrode
(ISE) method as a more reliable device which was previously utilized by Zohouri (2006)
and Cochrane (2006) [9,11]. However, other trialists such as Brown (1991) and
Sinadobaradaram (2008) administer/ plied Spectrophotometer which is said to be
further prone to potential errors [12,13].
In this study we attempted to measure the fluoride concentration of both tap water and
mineral bottled water as two major sources of fluoride which to the best of our
knowledge resembled only the Hurtado 2009 trial. Whereas in other reports, the trialists
solely assessed the fluoride content in either one of the two water supplies [14].
In order to assess the role of seasonal variations in the concentration of fluoride, we
collected our samples in two different seasons i.e. summer and winter. Our findings
confirmed those of Jezierska -Madziar’s (2004) and Davraz’s (2007) reporting that
higher fluoride concentration is associated with warm and dry climates. This could
possibly be associated with the chemical reactions of underground waters with volcanic
products. However the statistical analysis did not reveal any significant difference in this
respect [15, 16].
The results further revealed that the actual fluoride content measured by the trialists
were significantly lower than those displayed on the labels. This finding strongly
documented the previous reports all of which suggest that the manufacturers need to
enhance their commitment to high standards and pay more attention to the figures
stated on their products [5, 9, and 13].
The fluoride concentration of both bottled mineral water and tap water samples in the
present study was measured below the standard level. This might be attributed to the
type of local soil and its mineral contents, seasonal variations and possible presence of
volcanic deposits in underground water reservoirs [11, 13, 16, 17].
Conclusion:
The results indicate that the fluoride content of mineral bottled water and local tap water
in Tehran is less than optimum. Moreover this study shows that the mean concentration
of fluoride in public tap water is significantly higher than mineral bottled water and that
the actual fluoride content of bottled waters is significantly lower than the figures on their
labels.
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