(Annual Conference of the International Society of Environmental Epidemiology)
July 2000; 11(4): S153
Influence of Fluoride Exposure on Reaction Time and Visuospatial Organization in Children
Jaqueline Calderon, Machado Blenda, Navarro Marielena, Carrizales Leticia, Ortiz Maria Deogracias, Diaz-Barriga F.
University of North Caroline. Email: Jaqueline.Calderon@sph-unc.edu
Fluoride exposure is an important public health
problem in several Mexican states. In the city of San Luis Potosi, Mexico,
above 90% of the children have some degree of dental fluorosis. The main
source of exposure to fluoride is tap water. The objective of the study
was to evaluate the influence of chronic exposure to fluoride on neuropsychological
development in children. Sixty-one children aged 6 to 8 years were included.
Fluoride concentration in tap water ranged from 1.2 to 3 mg/L. Fluoride
exposure was measured in urine samples by electrothermal ion selective method.
Blood lead (PbB) was measured as indicator of lead exposure by atomic absorption
spectrophotometry. Height for age index (HAI) was calculated as indicator
of past nutritional status. Three tests were used to evaluate the neuropsychological
development: (1) Wechsler Intelligence Scale for Children Revisited version
for Mexico (WISC-RM), (2) Rey Osterreith-Complex Figure test and (3) Continuos
Performance Test (CPT). Mean value of fluoride in urine was 4.3 mgF/g creatinine
(1.6-10.8). Mean PhB value was 6.2 ug/dl (2.0-15.6). After controlling by
significant confounders, urinary fluoride correlated positively with reaction
time and inversely with the scores in visuospatial organization. IQ scores
were not influenced by fluoride exposure. An increase in reaction time could
affect the attention process, also the low scores in visuospatial organization
could be affecting the reading and writing abilities in these children.
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