Flawed MIREC fluoride and intelligence quotient publications: A failed attempt to undermine community water fluoridation

Abstract

ObjectiveTo assess the evidence presented in a set of articles that use the Canadian Maternal–Infant Research on Environmental Chemicals (MIREC) study database to claim that community water fluoridation (CWF) is associated with harm to foetal and infant cognitive development.MethodsCritical appraisal of measurements and processes in the MIREC database, and articles derived therefrom. MIREC's cohort is approximately 2000 pregnant women recruited in 10 centres across Canada, 2008–2011, leading to measuring 512 children aged 3–6 years in six cities. Fluoride exposure was measured by city fluoridation status, self‐reports and maternal spot urine samples. Intelligence Quotient (IQ) was measured using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI‐III) by different assessors in each city.ResultsMIREC's fluoride and IQ measurements are invalid and therefore cannot support the claim that CWF is associated with IQ decline in children.ConclusionsThe MIREC fluoride‐IQ articles' results should be considered unacceptable for legal and policy purposes; other water fluoridation studies and systematic reviews show no effect of fluoridation on cognition.

Fluoride and children’s IQ: evidence of causation lacking

“…The paper by Till et al (2020) uses data from the Maternal-Infant Research on Environmental Chemicals (MIREC) birth cohort database in Canada, as do several other recent fluoride-IQ papers (including Farmus et al 9 , also assessed as high quality by Taher et al, and low quality by Lambe et al 6 ). The MIREC cohort was not designed to evaluate fluoride and the studies using these data have been extensively critiqued 2,10 , with recent authors stating that these studies should be "considered unacceptable for legal and policy purposes" 11 .…”