The US National Toxicology Program’s systematic review of fluoride neurotoxicity has identified many studies reporting substantial loss of IQ from early life fluoride exposure. Several are mother-child cohort studies finding lowered IQ and increased risk of ADHD. ALSPAC provides an ideal data set to further examine the association between early life fluoride exposure and developmental neurotoxicity.

The ALSPAC cohort is expected to have relatively low fluoride exposure from drinking water because most of the recruitment area has concentrations below 0.2 mg/L. The main source of maternal fluoride exposure is expected to be diet, especially from tea. ALSPAC mother’s diet questionnaires indicate a wide range of tea consumption. Other exposure sources to be considered are fluoride supplements and dental products.

Neurodevelopmental outcomes to be examined include IQ scores; developmental, behavioral, and ADHD scores and diagnoses.

Covariates that may affect the neurodevelopmental outcomes or modify the effect of fluoride will be considered.

One proposed mechanism of fluoride developmental neurotoxicity is through impaired thyroid function of the pregnant mother so maternal thyroid hormone and iodine levels will be considered as modifying factors.

Several recent studies have found gene-fluoride interactions resulting in greater loss of IQ for children with certain genetic variants so those gene variants will also be considered as covariates.

The association of fluoride with lowered IQ or other neurodevelopmental deficits is of great public health importance. Millions of people have elevated fluoride exposure, through sources including drinking water, diet, and dental products.