York professor leads study that could help answer fluoride safety questions

Graphic showing different research terms
Graphic showing different research terms

A $300,000 grant from the National Institute of Health (NIH) will allow York University to lead the largest study to date that investigates whether early life exposure to low level fluoride affects the developing brain.

Christine Till
Christine Till

Faculty of Health Professor Christine Till, principal investigator of the study, will use the funding to determine if prenatal and childhood exposure to fluoride impacts learning abilities and behavioural problems in young Canadian children.

Previous studies led by Till and former PhD student, Ashley Malin, indicate that fluoride in tap water is associated with attention deficit hyperactivity disorder (ADHD) in children and adolescents. Findings were determined using information collected by the National Survey of Children’s Health as well as the Centre for Disease Control and Prevention (CDC) in the U.S.

This two-year study, however, will access data from a Canadian pregnancy cohort, Maternal Infant Research on Environmental Contaminants (MIREC), to determine whether or not there is a link.

The research team consists of scientists from complementary fields spanning environmental health (Professor Lanphear, Simon Fraser University; Professor Muckle, Universite Laval), dentistry (Dr. Martinez-Mier, Indiana University), toxicology (Professor Ayotte, University of Montreal), and environmental epidemiology (Professor Hornung, Cincinnati Children’s Hospital).

“Our study employs a prospective design that includes biomarkers of exposure to fluoride, detailed assessment of potential confounders, a comparison group, and the use of sensitive cognitive and behavioural measures that have been collected in one of the world’s most comprehensively characterized national pregnancy cohorts (MIREC),” said Till.

Fluoride concentrations will be measured using urine samples obtained in each trimester from a sample of 1,960 pregnant women living in 10 large Canadian cities – half of which add fluoride to municipal water.

The children born to these women have been followed since infancy and underwent cognitive testing between the ages of 3 and 4 years.

The study will also examine whether neuro-developmental outcomes differ among children who ingested infant formula using fluoridated versus non-fluoridated water. It will also examine whether serial urinary fluoride concentrations in pregnant women are higher in women who live in communities that fluoridate their municipal drinking water.

“We are doing this research because it addresses a topic of great public health relevance for both Canada and the United States where community water fluoridation is a widespread practice. Scientific advisory boards, including the National Toxicology Program, conclude that there is insufficient laboratory evidence to support or refute the likelihood of fluoride neurotoxicology.  We need high quality data to address this gap in knowledge,” said Till.

“Results of the study will have the potential to strengthen environmental health risk assessments related to water fluoridation and inform policy decisions about the safety of vulnerable populations, including young children and pregnant women, consuming fluoridated water.”

She describes the research as a “win-win” situation, where both potential outcomes will provide valuable information in the hotly contested fluoride issue.