ArticlePDF Available

Effect of high fluoride water on intelligence of school children in India


Abstract and Figures

The intelligence quotient (IQ) was measured in 190 school-age children, 12-13 years old, residing in two village areas of India with similar educational and socioeconomic conditions but differing in fluoride (F) concentration in the drinking water. The children in the high F area (drinking water F 5.5510.41 mg/L) had higher urinary F levels (6.13± 0.67 mg/L) than the children in the lower F area (drinking water F 2.01±0.09 mg/L; urinary F levels 2.30±0.28 mg/L). The mean IQ score of the 89 children in the high F area was significantly lower (91.7211.13), than that of the 101 children in lower F area (104.44±1.23). A significant inverse relationship was also present between IQ and the urinary F level. In agreement with other studies elsewhere, these findings indicate that children drinking high F water are at risk for impaired development of intelligence.
Content may be subject to copyright.
Research report
Fluoride 40(3)178–183
July-September 2007
Effect of high F water on children’s intelligence in India
Trivedi, Verma, Chinoy, Patel, Sathawara 178178
MH Trivedi,a RJ Verma,a NJ Chinoy,a† RS Patel,b NG Sathawarac
Ahmedabad, India
INOIP%Q6DGE%?:HM% G6E7H78;% 78% 9C?% R7::D;6%DG6DE%?S%(8H7D%C795%E7F7:DG% 6H><D97?8D:% D8H
CD96GV%$56%<57:HG68% 78%956%57;5% "%DG6D%@HG78U78;% CD96G%"%WVWWXKVYI% F;Z*B%5DH%57;56G
"% NVKIXKVKJ% F;Z*]% >G78DGQ% "% :6R6:E% NVPKXKVN^% F;Z*BV% $56% F6D8% (A% E<?G6% ?S% 956% ^J
<57:HG68% 78% :?C6G% "% DG6D% @IKYVYYXIVNPBV% /% E7;87S7<D89% 78R6GE6% G6:D97?8E57_% CDE % D:E?
_G6E689% T69C668% (A% D8H% 956% >G78DGQ% "% :6R6:V% (8% D;G66F689% C795% ?956G% E9>H76E
Keywords: Fluoride in drinking water; India school children; Intelligence quotient; Urinary
According to current research findings, fluoride (F) produces neuronal
dysfunction and synaptic injury by a mechanism that involves free radical
production and lipid peroxidation.1-4 A recent study revealed that a high F level in
drinking water depressed learning-memory ability of brain in Wistar rats,5 in
agreement with earlier findings of Mullenix et al. showing that F exposure caused
a common pattern of sex and dose-specific behavioral deficits in rats.6 Brain
histology of NaF-intoxicated rabbits revealed loss of molecular layer and glial cell
layer, and Purkinje neurons exhibited chromatolysis and acquired a ‘ballooned’
appearance.7 Reduction and even complete loss of Nissl substance was observed
in rabbit7 and rat8 brain.
In recent studies in our laboratory, we found a significant dose-dependent
reduction in DNA, RNA, and proteins in the cerebral hemisphere, cerebellum, and
medulla oblongata regions of the brain in mice.9-10 In related work, Wang and co-
workers11 recorded evidence of DNA damage in brain cells of adult rats exposed
to high F and low iodine. Effects of F on the thyroid gland and its function have
also been studied.12-14 Moreover, animal experiments on the effect of high F and
low iodine on biochemical indexes and the antioxidant defense of the brain have
revealed decreased learning-memory in offspring rats.15-16
An association of high F in drinking water with lower intelligence in children in
China has been reported by Li et al.17 Earlier, Xiang et al.18 determined a
benchmark concentration-response relationship between IQ <80 and the F level in
aFor Correspondence: RJ Verma, Department of Zoology, University School of Sciences,
Gujarat University, Ahmedabad-380 009, Gujarat, India, E-mail:;
bProfessor and Head, Dean Department of Education, University School of Psychology,
Philosophy & Education, Gujarat University, Ahmedabad-380 009, India.
cAsst. Director, Department of Hygiene, N.I.O.H (National Institute for Occupational Health),
Meghani Nagar, Ahmedabad-380 016, India. Deceased May 8, 2006.
Research report
Fluoride 40(3)178–183
July-September 2007
Effect of high F water on children’s intelligence in India
Trivedi, Verma, Chinoy, Patel, Sathawara 179179
drinking water was 2.32 mg F/L, and the lower-bound confidence limit was 1.85
mg F/L. By contrast, Spittle et al.19 found no trend for IQ to decline in children
drinking artificially fluoridated for seven years in an area of South Island, New
Zealand. Nevertheless, other studies indicate that exposure to increased levels of F
are associated with lower IQ.20-21 In India, both iodine deficiency disorders and
fluorosis due to excessive consumption of F cause two prevalent endemic diseases
that coexist in certain regions in the country.22 However, the majority of studies
that show a correlation between lower IQ and elevated F intake are from China,
and no such studies that we are aware of have been reported from India.
The aim of the present investigation was to examine F exposure of two groups of
school children and its impact on their intelligence quotients.
Our study was undertaken on 190 school-age children in the 6th and 7th standard
(12–13 years old) of the lower F area of Chandlodia, Ahmedabad (101 students),
and the high F area of Sachana (89 students), in the Sanand district of Gujarat,
India. The children were life-long residents of their respective locations with only
one school in each area. The nutritional and middle class socioeconomic status of
both areas is very similar and good, but slightly lower in Sachana. Iodized salt is
used in both areas.
The intelligence quotient (IQ) was measured in the children of both areas by
using a questionnaire prepared by Professor JH Shah, copyrighted by Akash
Manomapan Kendra, Ahmedabad, India, and standardized on the Gujarati
population with 97% reliability rate in relation to the Stanford-Binet Intelligence
Scale.23 Before the students were allowed to open the questionnaire, the
examiners gave a friendly explanation of the important instructions to avoid
mental stress for those taking the test. Questions were related to the educational
background of the children, and the test had to be completed in 8 min under the
supervision of examiners.
Scores were ranked as: mental retardation (IQ <70), borderline (IQ 70–79), dull
normal (IQ 80–89), normal (IQ 90–109), bright normal (IQ 110–119), superior (IQ
120–129), and very superior (IQ >129).18
The drinking water and urine samples of the children of both areas were
collected in plastic bottles, stored under refrigeration, and used for the
measurement of F using an ion selective electrode (Orion research, USA. Model
no 96-09).
Values are expressed as Mean±SEM. Student’s t test was used for statistical
analysis of the data, and values of p<0.05 were considered significant.
As seen in Table 1, mean urinary F levels were significantly higher in the
children living in the area where the F content in drinking water was high
compared to the area where it was much lower.
Research report
Fluoride 40(3)178–183
July-September 2007
Effect of high F water on children’s intelligence in India
Trivedi, Verma, Chinoy, Patel, Sathawara 180180
Table 2 shows that the mean IQ of the 89 children in the high F water area of
Sachana was 12.2 percent lower than the mean IQ of the 101 children in the lower
F area of Chandlodia, which is highly significant. Significant differences between
the IQ of male and female children within each of the two areas were also found.
As seen in Table 3 and illustrated in the Figure, the IQ of nearly half the children
in the lower F area of Chandlodia was in the normal range of 90 to 109. The IQ of
38.61% the children in this village area was above the normal range, and only
11.88% were below the normal range. On the other hand, the IQ of a much larger
percentage of the children in the high F area of Sachana was in the normal range,
and only 2.25% were above that range, with none with an IQ above 119.
Moreover, in Sachana the IQ of 28.09% of the children was below the normal
range—over twice the percentage found in Chandlodia.
$DT:6%IV Drinking water and urinary F level of children living in lower F Chandlodia and high F Sanacha (Mean ± SEM)
Area Number of children
Level of F in drinking water
Urinary F level
Ahmedabad District
101 2.01 ± 0.009 2.30 ± 0.28
Sanacha, Sanand District 89 5.55 ± 0.41* 6.13 ± 0.67*
*p<0.001 (Compared to lower F level).
$DT:6%NV IQ scores of school children (numbers in parenthesis) living in lower F Chandlodia
and high F Sachana (Mean ± SEM)
Group Chandlodia, Ahmedabad Sachana, Sanand
104.44 ± 1.23 (101) 91.72 ± 1.13** (89)
According to gender
Male (Total 6th/7th) 104.80 ± 1.47 (62) 90.24 ± 1.58** (56)
Female (Total 6th/7th) 103.87 ± 2.21 (39) 94.15 ± 1.35 (33)
According to gender and grade level
6th Standard
Male 105.22 ± 2.45 (31) 96.25 ± 2.73 (20)
Female 105.55 ± 2.95 (18) 93.35 ± 2.23 (14)
7th Standard
Male 104.38 ± 1.67 (31) 86.70 ± 1.70** (36)
Female 102.42 ± 3.27 (21) 94.73 ± 1.72* (19)
*p<0.05; p<0.01; **p<0.001 (compared to higher IQ group).
$DT:6%PV IQ distribution in children in lower F Chandlodia and high F Sachana
Chandlodia Sachana
Male Female Total % Male Female Total %
!130 2 0 2 1.98 0 0 0 0
120–129 2 1 3 2.97 0 0 0 0
110–119 22 12 34 33.66 2 0 2 2.25
90–109 31 19 50 49.50 35 27 62 69.66
80–89 5 4 9 8.91 10 4 14 15.73
70–79 0 2 2 1.98 6 2 8 8.99
"69 0 1 1 0.99 3 0 3 3.37
Total 62 39 101 100 56 33 89 100
Research report
Fluoride 40(3)178–183
July-September 2007
Effect of high F water on children’s intelligence in India
Trivedi, Verma, Chinoy, Patel, Sathawara 181181
This study indicated that the mean IQ level of students exposed to high F
drinking water was significantly lower than that of the students exposed to a lower
F level drinking water. Because the kidney is the principal organ for the excretion
of F, the rate or degree of exposure to F was checked by analyzing the urinary F
level.22 In high F Sachana, more children had IQ scores below the normal 90–109
range than in lower F Chandlodia, where more children scored above the normal
level. It thus appears that elevated F exposure depressed higher levels of
intelligence even more than it affected normal and below normal intelligence of
the children. Overall, the difference in mean IQ between the two groups was
12.2%, which, statistically, is highly significant. The normal IQ range for these
areas is 100–110.23
The biomechanism of the action of F in reducing IQ is not clear. However, there
is evidence that it may involve in alteration of membrane lipid and reduction in
cholinesterase activity in the brain. Guan et al.25 demonstrated that the contents of
phospholipids and ubiquinone are altered in the brain of rats affected by chronic
fluorosis, and therefore changes in membrane lipids could be involved in the
pathogenesis of this disorder. F is also known to have adverse effects on
cholinesterase activity involved in the hydrolysis of esters of choline.26 This toxic
effect may lead to altered utilization of acetylcholine, thus affecting the
transmission of nerve impulses in brain tissue.27-29 Recently, NaF has been found
to alter the levels of dopamine, serotonin, 5-hydroxyindoleacetic acid,
homovanillic acid, norepinephrine, and epinephrine in the hippocampus and
neocortex regions of the rat brain.30 Earlier, Yu et al.31 demonstrated changes in
neurotransmitters and their receptors in human fetal brain from an endemic
fluorosis area.
It is also well established that F can pass through the placenta to the fetus, and
with subsequent continuous exposure to F during childhood, it may have adverse
2.97 1.98
? 69 70-79 80-89 90-109 110-119 120-129 ? 130
Range of intelligence quotient
Range of intelligence quotient
Percent distribution
"7;>G6V IQ score distribution of children in the high and lower F areas.
High fluoride area
Low fluoride area
Research report
Fluoride 40(3)178–183
July-September 2007
Effect of high F water on children’s intelligence in India
Trivedi, Verma, Chinoy, Patel, Sathawara 182182
effects on the developing brain, thereby causing decreased IQ in children.32-34 The
greater reduction in IQ of children exposed to high F in our study compared to
previous studies might reflect the magnitude of the difference in F concentration in
the drinking water of the two areas, the modified version of the IQ test, and/or
environmental, genetic, and cultural variations. The difference in F concentration
in the drinking water between the two areas is 3.54 mg/L, which is higher in
comparison to the studies done by Lu et al.20 (2.78 mg/L), Xiang et al.18 (2.11 mg/
L), and Seraj et al.35 (2.1 mg/L).
Thyroid hormones play an important role in development of brain and thus
might also affect IQ level. As noted in the Introduction, important aspects of F/
iodine interactions on thyroid function are now being explored,12-14 and Susheela
et al.22 have found that elevated F intake may cause iodine deficiency in fluorotic
individuals, even when they reside in non-iodine deficient areas.
Clearly, for the benefit of future generations, urgent attention needs to be
directed to improving our understanding of and correcting adverse effects of F on
We take this opportunity to express our gratitude to Ms Yasheshvini A Trivedi
and Twinkle N Tiwari for their kind assistance in conducting the IQ test. We also
thank the technical staff of the National Institute of Occupational Health, Mr
Pradeep Arya and Mr Idrish Shaikh, for their kind help with the analysis of urine
and water samples.
1 Guo XY, Sun GF, Sun YC. Oxidative stress from fluoride-induced hepatotoxicity in rats.
Fluoride 2003;36:25-9.
2 Shivarajashankara YM, Shivashankara AR, Rao SH, Bhar PG. Oxidative stress in children
with endemic skeletal fluorosis. Fluoride 2001;34:103-7.
3 Shivarajashankara YM, Shivashankara AR, Bhat PG, Rao SH. Effect of fluoride intoxication
on lipid peroxidation and antioxidant systems in rats. Fluoride 2001;34:108-13.
4 Rzeuski R, Chlubek D, Machoy Z. Interactions between fluoride and biological free radical
reactions. Fluoride 1998;31:43-5.
5 Wu C, Gu X, Ge Y, Zhang J, Wang J. Effects of fluoride and arsenic on brain biochemical
indexes and learning-memory in rats. Fluoride 2006;39:274-79.
6 Mullenix PJ, Denbesten PK, Schunior A, Kernan WJ. Neurotoxicity of sodium fluoride in
rats. Neurotoxicol Teratol 1995;17:169-77.
7 Shashi A. Histopathological investigation of fluoride-induced neurotoxicity in rabbits.
Fluoride 2003;36:95-05.
8 Shivarajashankara YM, Shivashankara AR, Bhat PG, Rao SM, Rao SH. Histological
changes in the brain of young fluoride-intoxicated rats. Fluoride 2002;35:12-21.
9 Verma RJ, Trivedi MH, Chinoy NJ. Black tea amelioration of sodium fluoride-induced
alterations of DNA, RNA, and protein contents in the cerebral hemisphere, cerebellum, and
medulla oblongata regions of mouse brain. Fluoride 2007;40:7-12.
10 Trivedi MH, Verma RJ, Chinoy NJ. Amelioration by black tea of sodium fluoride-induced
changes in protein content of cerebral hemisphere, cerebellum, and medulla oblongata in
brain region of mice. Acta Pol Pharma-Drug Res 2007;64:221-25.
11 Ge Y, Ning H, Wang S, Wang J. Comet assay of DNA damage in brain cells of adult rats
exposed to high fluoride and low iodine. Fluoride 2005;38:209-14.
Research report
Fluoride 40(3)178–183
July-September 2007
Effect of high F water on children’s intelligence in India
Trivedi, Verma, Chinoy, Patel, Sathawara 183183
12 Zhan X, Li J, Wang M, Xu Z. Effects of fluoride on growth and thyroid function in young pigs.
Fluoride 2006;39:95-100.
13 Trabelsi M, Guermazi F, Zeghal N. Effect of fluoride on thyroid function and cerebellar
development in mice. Fluoride 2001;34:165-73.
14 Ge Y, Ning H, Wang S, Wang J. DNA damage in thyroid gland cells of rats exposed to long-
term intake of high fluoride and low iodine. Fluoride 2005;38:318-23.
15 Wang J, Ge Y, Ning H, Wang S. Effects of high fluoride and low iodine on biochemical
indexes of the brain and learning-memory of offspring rats. Fluoride 2004;37:201-08.
16 Wang J, Ge Y, Ning H, Wang S. Effects of high fluoride and low iodine on oxidative stress
and antioxidant defense of the brain in offspring rats. Fluoride 2004;37:264-70.
17 Li XS, Zhil JL, Gao RO. Effect of fluoride on intelligence in children. Fluoride 1995;28:189-
18 Xiang Q, Liang Y, Chen L, Wang C, Chen B, Chen X, Zhou M. Effect of fluoride in drinking
water on children’s intelligence. Fluoride 2003;36:84-94.
19 Spittle B, Ferguson D, Bouwer C. Intelligence and fluoride exposure in New Zealand
children [abstract]. Fluoride 1998;31:S13.
20 Lu Y, Sun ZR, Wu LN, Wang X, Lu W, Liu SS. Effect of high-fluoride water on intelligence in
children. Fluoride 2000;33:74-8.
21 Zhao LB, Liang GH, Zhang DN, Wu XR. Effect of a high fluoride water supply on children’s
intelligence. Fluoride 1996;29:190-92.
22 Susheela AK, Bhatnagar M, Vig K, Mondal NK. Excess fluoride ingestion and thyroid
hormone derangements in children living in Delhi, India. Fluoride 2005;38:98-08.
23 Desai K, Desai H. Psychological Measurement, Gujarat University Press, Gujarat
State;India;1989. [in Gujarati].
24 Szymaczek JO, Borysewicz-Lewicka M. Urinary fluoride levels for assessment of fluoride
exposure of pregnant women in Poznan, Poland. Fluoride 2005;38:312-17.
25 Guan ZZ, Wang YN, Xiao KQ, Dai DY, Chen YH, Liu JL, Sindelar P, Dallner G. Influence of
chronic fluorosis on membrane lipids in rat brain. Neurotoxicol Teratol 1999;20:537-42.
26 Vani LM, Reddy KP. Effects of fluoride accumulation on some enzymes of brain and
gastrocnemius muscle of mice. Fluoride 2000;33:17-26.
27 Marks DB, Marks AD, Smith CM. Basic Medical Biochemistry: A Clinical Approach.
Baltimore, MD, USA: Lippincott, Williams & Wilkins; 1996.
28 Blaylock RL. Excitotoxicity: A possible central mechanism in fluoride neurotoxicity. Fluoride
29 Blaylock RL. Fluoride neurotoxicity and excitotoxicity/microglial activation: Critical need for
more research. Fluoride 2007;40:89-92.
30 Chirumari K, Reddy PK. Dose-dependent effects of fluoride on neurochemical milieu in the
hippocampus and neocortex of rat brain. Fluoride 2007;40:101-10.
31 Yu Y, Wang W, Dong Z. Changes in neurotransmitters and their receptors in human foetal
brain from an endemic fluorosis area. Chang Hua Liu Hsing Ping Hsueh Tsa Chih
32 Verma RJ, Guna Sherlin, DM. Sodium fluoride-induced hypoproteinemia and hypoglycemia
in parental and F1-generation rats and amelioration by vitamins. Food Chem Toxicol
33 Maduska AL, Ahokas RA, Anderson GD, Liphshitz J, Morrison JC. Placental transfer of
intravenous fluoride in pregnant dams. Am J Obstet 1980;136:84-86.
34 Teotia M, Teotia SPS, Singh RK. Metabolism of fluoride in pregnant women residing in
endemic fluorosis areas. Fluoride 1979;12:58-64.
35 Seraj B, Shahrabi M, Falahzade M, Falahzade F, Akhondi N. Effect of fluoride concentration
in drinking water on children’s intelligence. J Dent Tehran Univ Med Sci 2006;19:80-86.
[abstract in this issue of !luor&'e, p. 200-1].
Copyright © 2007 International Society for Fluoride Research.
Editorial Office: 727 Brighton Road, Ocean View, Dunedin 9035, New Zealand.
... According to research, fluoride can cause negative biochemical and functional alterations in the developing human brain [4]. High levels of fluoride in drinking water may have a negative impact on intelligence, which could be a major health issue. ...
... The collected samples were stored in an ice box and were submitted to the Rajasthan State Pollution Control Board within eight hours of the collection for the analysis of fluoride content. The concentration of fluoride in urine was assessed using the Selective Ion Electrode Technique [4,[8][9][10]. In order to ensure reliability, the sample was appraised thrice, and the mean value was documented. ...
... Raymond Cattell asserts that intelligence increases until the age of 15 and thereafter remains constant. Additionally, examining these age groups made it easier to compare the results of this study with those of numerous other studies in which kids in a comparable age group were examined [4,5,9]. Children's IQs were measured using Raven's Coloured Progressive Matrices test, which is a "culturally fair" test suited for comparing children in terms of their immediate capacities for observation and clear reasoning. ...
Background: The preliminary study was undertaken with the aim to assess the effect of fluoride content in water on the Intelligence Quotient (IQ) of school children aged 12-13 years residing in areas that differ with respect to fluoride levels. Materials and methods: The IQ was measured using Raven's Colored Progressive Matrices in 90 children, who were life-long residents in three villages (30 children each) of similar population size but differing in the level of fluoride in drinking water. Urinary fluoride concentration was measured using the selective ion electrode technique. One-way ANOVA was used for the statistical analysis of the data. Results: Children who lived in locations with fluoride levels of 1.60, 6.70, or 2.80 parts per million in their drinking water had urinary fluoride concentrations of 1.60, 6.82, or 2.69 parts per million, and IQ scores of 16.77 + 8.24, 19.36 + 9.98, or 21.87 + 7.47, respectively. Conclusion: The results indicated that there was a positive correlation between excess fluoride in drinking water and IQ.
... The F concentrations in drinking water categorized as low exposure in the selected studies ranged from 0.19 ppm 25 to 2.01 ppm 26 , while high doses ranged from 1.5 ppm 23,27 to 8.3 ppm 28 . Some studies considered a third intermediate category 23,[29][30][31][32][33] , which ranged from 0.5 ppm 30 to 3.1 ppm 33 . ...
... Regarding the source of sample used for the estimation of F exposure, most of the studies evaluated the drinking water alone 20 20,22,[26][27][28][37][38][39][40][41] , and in the air 24 . Some studies did not quantify the F levels, however determined the concentration from data available from national databases or electronic addresses 32,42,43 . ...
... In relation to the parameters of cognitive assessment, in 26 studies the IQ was used to estimate a comparative intellectual and stabilizing capacity between the high and low groups, whereas one study 23 evaluated neurological manifestations such as headache, insomnia, lethargy, polydipsia and polyuria. The tests applied for IQ evaluation varied among the studies, being the "Raven's Standard Progressive Matrices test" 20,21,27,[29][30][31]34,38 and the "Standardized Chinese Test" 22,28,37,40,41,44,46 the most used, followed by "Raven's Color Progressive Matrices" 25,32,33,43 , "Stanford-Binet Intelligence Scale" 26,39 , "Chinese Binet IQ Test" 24 , "Prueba Raymond B Cattell" 35 , "Wechsler Preschool Guidelines and Primary Intelligence Scale (WPPSI)" 36 , "Rui Wen Prueba Handbook" 45 and "Form Board Test" 42 . The descriptive study 23 used as a tool for data collection, interviews with questionnaires prepared by qualified professionals. ...
Full-text available
Different studies have suggested that fluoride is related to neurological disorders in children and adolescents, but clinical evidences of which neurological parameters associated to fluoride exposure are, in fact, still controversial. In this way, this systematic review and meta-analysis aimed to show if there is an association between fluoride exposure from different sources, doses and neurological disorders. Terms related to “ Humans ”; “ Central nervous system ”; “ Fluorides ”; and “ Neurologic manifestations ” were searched in a systematic way on PubMed , Scopus , Web of Science , Lilacs , Cochrane and Google Scholar. All studies performed on humans exposed to fluoride were included on the final assessment. A meta-analysis was then performed and the quality level of evidence was performed using the GRADE approach. Our search retrieved 4,024 studies, among which 27 fulfilled the eligibility criteria. The main source of fluoride was naturally fluoridated water. Twenty-six studies showed alterations related to Intelligence Quotient (IQ) while only one has evaluated headache, insomnia, lethargy, polydipsia and polyuria. Ten studies were included on the meta-analysis, which showed IQ impairment only for individuals under high fluoride exposure considering the World Health Organization criteria, without evidences of association between low levels and any neurological disorder. However, the high heterogeneity observed compromise the final conclusions obtained by the quantitative analyses regarding such high levels. Furthermore, this association was classified as very low-level evidence. At this time, the current evidence does not allow us to state that fluoride is associated with neurological damage, indicating the need for new epidemiological studies that could provide further evidences regarding this possible association.
... As fluorspar it is found in sedimentary rocks and as cryolite in igneous rocks [Mohapatra M. S., 2009]. In micromolar level fluoride is useful as it helps in cell proliferation but in higher concentration millimolar concentration it binds with the functional amino acid group and inhibit the enzyme activity at the various active centers [Trivedi M.H.,2007;] Adamek E.,2005]. In India the fluoride concentration in underground water is higher (1.5-6.5 mg lit -1 WHO,1993), the limit given by the World Health organization (WHO) is 1.5 mg lit -1 for drinking water [WHO,2004]. ...
... Fluoride also influences the shape and mobility of sperm in males (Chinoy & Narayana 1994). When it comes to neurobehavior (Trivedi et al. 2007), intellectual quotient (IQ) and thinking capacity loss occur. Children's mental abilities are impaired. ...
Full-text available
The presence of fluoride in the groundwater in the Thirukkazhukundram Block in south India is now becoming an increasingly alarming issue. With the semi-arid climatic conditions, charnockite and gneiss rocks form the basement, contributing to the geology of the study area. The pre-monsoon (August 2016) and post-monsoon (February 2017) fluoride concentrations have an average output of 1.3 mg.L-1 and 0.72 mg.L-1 respectively. As of date, only in Neikuppi, the fluoride contamination is found to be 2 mg.L-1 in pre-monsoon which is beyond the accepted limit as per the WHO standards. Other 29 locations taken up for study have fluoride value fluctuation from 1 mg.L-1 to 2 mg.L-1 in the pre-monsoon and from 0 to 1.5 mg.L-1 in the post-monsoon. The main factor responsible for this fluoride contamination lies in the study area’s hydro-geological condition which must be attended to immediately to prevent a public health problem in the future.
... Early studies observed IQ decrease in areas with excessive fluoride concentration in drinking water globally, and in most of which, the water fluoride concentrations were extremely high (e.g. WF > 5 mg/L) (Seraj et al., 2012;Trivedi et al., 2007). In recent years, more studies focused on the relationship between low-moderate fluoride exposure and IQ, and the results had public health implications for population more widely. ...
Full-text available
Background Excessive fluoride exposure is related to adverse health outcomes, but whether dopamine (DA) relative genes are involved in the health effect of low-moderate fluoride exposure on children’s intelligence remain unclear. Objectives We conducted a cross-sectional study to explore the role of DA relative genes in the health effect of low-moderate fluoride exposure in drinking water. Methods We recruited 567 resident children, aged 6–11 years old, randomly from endemic and non-endemic fluorosis areas in Tianjin, China. Spot urine samples were tested for urinary fluoride concentration, combined Raven`s test was used for intelligence quotient test. Fasting venous blood were collected to analyze ANKK1 Taq1A (rs1800497), COMT Val158Met (rs4680), DAT1 40 bp VNTR and MAOA uVNTR. Multivariable linear regression models were used to assess associations between fluoride exposure and IQ scores. We applied multiplicative and additive models to appraise single gene-environment interaction. Generalized multifactor dimensionality reduction (GMDR) was used to evaluate high-dimensional interactions of gene-gene and gene-environment. Results In adjusted model, fluoride exposure was inversely associated with IQ scores (β = −5.957, 95% CI: −9.712, −2.202). The mean IQ scores of children with high-activity MAOA genotype was significantly lower than IQ scores of those with low-activity (P = 0.006) or female heterozygote (P = 0.016) genotype. We detected effect modification by four DA relative genes (ANKK1, COMT, DAT1 and MAOA) on the association between UF and IQ scores. We also found a high-dimensional gene-environment interaction among UF, ANKK1, COMT and MAOA on the effect of IQ (testing balanced accuracy = 0.5302, CV consistency: 10/10, P = 0.0107). Conclusions Our study suggests DA relative genes may modify the association between fluoride and intelligence, and a potential interaction among fluoride exposure and DA relative genes on IQ.
Risk assessment is a term which encompasses the entire process of hazard/risk identification, risk analysis, risk evaluation, and control. The term ‘risk’ is commonly believed to be associated with industrial operation; however, categorisation of risk reveals common elements, which can be applied to avoid hazards in other areas. Risk in a wider context is related to the probable harmful effects occurring to human health and/or ecological systems as a result of exposure to environmental stressors. The unsustainable use of natural resources creates stress and causes risks to ecology and human health that lead to social issues in surrounding communities, such as low quality of health and unemployment. Although natural events may be responsible for risk, anthropogenic activities are the major basis of risk to the environment and humans. Environmental risks present themselves as the probability of temporary or permanent changes to the atmosphere, hydrosphere, and lithosphere due to human activities that result in the loss of biodiversity, global warming, and climate change. The risk factor can be understood by calculating relative risk, attributable risk, and odds ratio. The risks occur primarily from exposure to factors such as occupational exposure, environmental exposure, biological exposure, and chemical exposure. The magnitude of the impact of risk on humans or wildlife depends on the path of exposure (inhalation, ingestion, and dermal), amount of exposure (dose), and duration of exposure. The severity of overall risk is dependent upon a range of factors and scenarios. Application of risk assessment enables taking care of safety and security in environmental, ecological, and social issues so that the well-being of humans and ‘Mother Earth’ can be managed. To ensure the safety and security of environmental sustainability, this chapter will focus on environmental contaminants and their risk to human health by projecting five key steps in the process of risk assessment.
The present study makes an attempt to mainly design to analyze the impact of fluoride in plain tropical central India and affecting health conditions of the school children. Fluoride naturally, a toxic material for the human beings but its more concentration in the body due to anthropogenic activities increases the risk of more dangerous outcomes. We utilized ionic concentration, hydrochemistry, fluoride content and health risk assessed from the different collected water samples in the month of June, 2017. This study shows the concentration of fluoride content in water sample ranged from 0.08-2.4 mg/l (mean = 0.6 mg/l) and had positive relation with the pH (r = 0.49), HCO3⁻ (r = 0.29) and Na⁺ (r = 0.20). Few, 9.18% water sample out of total collected samples were exceeding the permissible limit (> 1.5 mg/l) of fluoride content in groundwater which was not suitable for drinking purpose due to the heavy loading of fluoride content.
Full-text available
Arsenic (As), and fluoride (F⁻) are potent contaminants with established carcinogenic and non-carcinogenic impacts on the exposed populations globally. Despite elevated groundwater As and F⁻ levels being reported from various regions of Pakistan no biomonitoring study has been reported yet to address the co-exposure impact of As and F⁻ among school children. We aimed to investigate the effects of these two contaminants on dental fluorosis and intelligence quotient (IQ) along with the induction of oxidative stress in rural children under co-exposed conditions. A total of 148 children (5 to 16 years old) from the exposed and control group were recruited in the current study from endemic rural areas of Lahore and Kasur districts, Pakistan having elevated As and F⁻ levels in drinking water than permissible limits. We monitored malondialdehyde and its probable association with antioxidants activity (SOD, CAT, and GR) as a biomarker of oxidative stress. GSTM1/T1 polymorphisms were measured to find the impact of As on health parameters. Mean urinary concentrations of As (2.70 vs. 0.016 µg/L, P < 0.000) and F⁻ (3.27 vs. 0.24 mg/L, P < 0.000) as well as the frequency of dental fluorosis were found elevated among the exposed group. The cases of children with lower IQ were observed high in the exposed group. Additionally, lower concentrations of antioxidants (SOD, CAT, and GR) were found suggesting high susceptibility to F⁻ toxicity. The findings suggest that F⁻ accounted for high variations in health parameters of children under the co-exposure conditions with As.
The aim of the present study was to investigate, by a systematic literature review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the effect of exposure to fluoride (F) on the Intelligence Quotient (IQ) of school children, a current topic of debate in the scientific community. The study was confined to documents that examined F exposure and IQ in school children in South Asia in the period 2001 to 2020. Thirteen of the 16 papers included in the study found that exposure to high fluoride levels in drinking water was associated with an adverse effect on IQ. The range of the drinking water level was 0.108 to 14.3 mg/L. Other factors that were identified as affecting IQ were annual family income, parent's occupation, parent's education, iodine availability, drinking water arsenic levels, blood lead, and nutrition. This study concluded that there was a need for countries to have national level policies for raising awareness of the potential for F to adversely affect IQ and for providing safe drinking water without high F levels.
Arsenic (As), and fluoride (F-) are potent contaminants, widely disturbed through drinking water and responsible for various health implications in the exposed population. We aimed to investigate the effects of these two contaminants on dental fluorosis and intelligence quotient (IQ) with the induction of oxidative stress in rural children under the co-exposed scenario. A total of 148 children (5 to 16 years old) from the exposed and control group were incorporated in the study, and samples of biological matrices were collected. Dental fluorosis through Dean's index and IQ with the help of the Wechsler scale of intelligence (WISC-IV) patterned test were measured. We also monitored malondialdehyde (MDA) and its probable association with antioxidants activity (SOD, CAT, and GR) as a biomarker for oxidative stress. GSTM1/T1 polymorphism was estimated to find their role in the urinary As metabolism. Mean urinary concentration of As (2.70 vs. 0.016 μg/L, P<0.000) and F- (3.27 vs. 0.24 mg/L, P<0.000) were quite higher in the exposed group as well as the frequency of dental fluorosis. The rate of children with lowered IQ cases was less in control than the exposed group. Additionally, lower concentrations of antioxidants (SOD, CAT, and GR) were found suggesting high susceptibility to fluoride toxicity. The percentage for null genotype carriers for GSTT1 was higher in exposure than the control group. The findings indicated that F- was accounted for high variations associated with dental fluorosis, lower intelligence quotient, and higher oxidative stress in children under the co-exposure scenario.
Full-text available
Effects of fluoride (F) on lipid peroxidation and enzyme activity levels in the hippocampus and neocortex were studied in 6- to 7-week-old female Wistar rats in five groups of six administered intraperitoneal doses of NaF in physiological saline over the range of 0, 1, 5, 10, and 20 mg NaF/kg bw/day for 14 days. Body weight and brain index decreased significantly (p<0.05) as F levels increased in the hippocampus and neocortex. Activities of the free radical enzymes superoxide dismutase (SOD), glutathione S-transferase (GST) and catalase (CAT) likewise decreased significantly (p<0.05), whereas the level of lipid peroxidation (LPO) and the activities of glutathione peroxidase (GPX) and xanthine oxidase (XOD) increased compared with those of the control group. The enzymes of secondary signaling, protein kinase C (PKC) and neuronal nitric oxide synthase (nNOS), also increased compared with the control. Dopamine, serotonin, 5-hydroxyindoleacetic acid and homovanillic acid levels likewise increased, whereas norepinephrine and epinephrine levels decreased. The NaF administered groups showed dose-dependent responses with more significant effects in the two fhigher dosage groups. Although NaF treatment produced significant neurochemical alterations in both the hippocampus and neocortex, there was not much difference in the degree of effects in the two organs.
Brain tissues for neurohistopathological study were obtained at autopsy from albino rabbits that had been subcutaneously injected for 15 weeks with 0, 5, 10, 20, and 50 mg of sodium fluoride in 1 mL of aqueous solutions/kg bw/day. Neuropathological changes occurred with loss of the molecular layer and glial cell layer in the brain tissues of rabbits exposed to the three higher fluoride doses. The Purkinje neurones exhibited chromatolysis and acquired a "ballooned" appearance. Nissl substance showed various degrees of decrease and even complete loss. Fragmented particles were retained in the perinuclear zone. The perikaryon showed vacuolization, and spheroid bodies were present in the neuroplasm. These cytoplasmic inclusions appeared as various sized ovoid bodies or elongated eosinophilic masses due to which the nucleus was shifted to the periphery. These neurotoxic changes in the brain suggested that there was a direct action of fluoride upon the nerve tissue which was responsible for central nervous system problems such as tremors, seizures, and paralysis indicating brain dysfunction seen at the two highest doses.
The exact mechanism of the neurotoxic effect of fluoride and aluminofluoride complexes on the brain has not been fully elucidated, although there is compelling evidence that it is closely related to that of heavy metal neurotoxicities as well as a host of neuropathological conditions. These involve an interaction between excitotoxic amino acids and proinflammatory cytokines, both of which are released in high concentrations with microglial activation. It is important that research be undertaken to explore and assess fluoride activation of microglia, the resident immune cells in the brain.
Free ionic fluoride concentrations were measured in the maternal blood plasma, cord blood plasma and the urine of pregnant and age matched nonpregnant women in two groups of subjects. Group 1 included females who had been living in endemic fluorosis areas with the mean intake of 21 mg/day of fluoride from drinking water and Group 2 consisted of women from non-endemic areas with the mean daily intake of 1.5 mg of fluoride from drinking water. The ionized fluoride concentrations in the maternal plasma and the urine decreased during the course of pregnancy; they were at their lowest at 36 weeks of gestation. In the nonpregnant controls these values remained largely unchanged. In the maternal and cord blood plasm obtained at the time of cesarean section the fluoride concentrations were similar and did not support the concept of a placental fluoride barrier. The higher fluoride content in the plasma and urine of the women in the endemic group (10 ppm F - in drinking water) indicated a direct relationship of these values to the amount of fluoride ingested. The fall in the maternal plasma and urine fluoride concentration during pregnancy is believed to be due to increasing accumulation of fluoride in the rapidly mineralizing fetal skeleton.
Oral administration of sodium fluoride (NaF, 6 and 12 mg/kg body weight/ day) to Swiss male albino mice for 30 days caused significant, dose-dependent reduction in DNA, RNA, and protein contents in cerebral hemisphere, cerebellum, and medulla oblongata of the brain. After 30 days of NaF treatment, followed by withdrawal of treatment for 30 days, partial but significant amelioration occurred. Administration of 2% black tea extract alone for 30 days did not cause any significant effect. However, concurrent administrations of NaF and black tea extract for 30 days cause significant amelioration in all parameters studied.
Nine-six Wistar rats were randomly divided into four groups of 24 rats in each group (female:male - 1:1). Over a period up to 90 days, with one untreated group as controls, the other three groups were administered, respectively, high fluoride (100 mg NaF/L), high arsenic (50 mg As2O3/L), or both the same high fluoride and high arsenic concentrations in their drinking water in order to assess their effects on learning-memory ability and brain function. In comparison with the controls, learning-memory ability was depressed by high fluoride (HiF), high arsenic (HiAs), and their combination (HiF+HiAs). Brain protein contents decreased significantly in the HiF+HiAs group at days 10 and 30, and decreased cholinesterase (ChE) activities occurred in the HiF group at day 10, and in the HiF+HiAs group at days 10 and 90. Moreover, in the HiAs group, ChE activity was increased at day 30 and then decreased significantly at day 90. The total antioxidant capacity (T-AOC) in the brain was decreased in the three exposed groups. The hydrosulfide group (-SH) content of brains was decreased markedly only by HiAs. These results suggest that learning-memory ability and brain function in rats are affected by HiF and HiAs and that oxidative stress in the brain may be one of the causes of this damage.
Recent evidence indicates that fluoride produces neuronal destruction and synaptic injury by a mechanism that involves free radical production and lipid peroxidation. For a number of pathological disorders of the central nervous system (CNS), excitotoxicity plays a critical role. Various studies have shown that many of the neurotoxic metals, such as mercury, lead, aluminum, and iron also injure neural elements in the CNS by an excitotoxic mechanism. Free radical generation and lipid peroxidation, especially in the face of hypomagnesemia and low neuronal energy production, also magnify excitotoxic sensitivity of neurons and their elements. This paper reviews briefly some of the studies that point to a common mechanism for the CNS neurotoxic effects of fluoride and calls for research directed toward further elucidation of this mechanism.
In Shanxi Province, China, children living in the endemic fluoride village of Sima (water supply F = 4.12 mg/L) located near Xiaoyi City had average IQ (97.69) significantly lower (p < 0.02) than children living to the north in the nonendemic village of Xinghua (F = 0.91 mg/L; average IQ = 105.21). These differences were not associated with gender, but the IQ scores were directly related to educational level of the parents.