Effect of high F water on children’s intelligence in India
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
178 178
EFFECT OF HIGH FLUORIDE WATER ON INTELLIGENCE
OF SCHOOL CHILDREN IN INDIA
MH Trivedi,a RJ Verma,a NJ Chinoy,a† RS Patel,b NG Sathawarac
Ahmedabad, India
SUMMARY: The intelligence quotient (IQ) was measured in 190 school-age children,12–13years 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 5.55±0.41 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 (91.72±1.13), 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. Keywords: Fluoride in drinking water; India school children; Intelligence quotient; Urinary
fluoride.
INTRODUCTION
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 oworkers11 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 .......................
Fluoride 40(3)178–183
July-September 2007
Effect of high F water on children’s intelligence in India
Trivedi, Verma, Chinoy, Patel, Sathawara
178 178
EFFECT OF HIGH FLUORIDE WATER ON INTELLIGENCE
OF SCHOOL CHILDREN IN INDIA
MH Trivedi,a RJ Verma,a NJ Chinoy,a† RS Patel,b NG Sathawarac
Ahmedabad, India
SUMMARY: The intelligence quotient (IQ) was measured in 190 school-age children,12–13years 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 5.55±0.41 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 (91.72±1.13), 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. Keywords: Fluoride in drinking water; India school children; Intelligence quotient; Urinary
fluoride.
INTRODUCTION
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 oworkers11 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 .......................
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