Richard Musgrove
Zoologist, Dr Richard Musgrove is a science journalist based in Far North Queensland.
A small but decade-long study on the effects of fluoride in drinking water in Bangladesh, suggesting a link between the chemical and lower cognitive abilities in kids, has raised the eyebrows of other experts.
The work was by a team from the Institute of Environmental Medicine at Sweden’s highly respected Karolinska Institute; the Department of Women’s and Children’s Health at Uppsala University, also in Sweden, and the Maternal and Child Health Division of the International Centre for Diarrhoeal Disease Research at Dhaka in Bangladesh.
In the paper, just published in the open-source journal, Environmental Health Perspectives, the researchers say fluoride exposure as a foetus or child may reduce IQ in Bangladeshi children.
The study followed 500 Bangladeshi mothers and their children, sampling urine from the mothers, before birth and from the children at 5 and 10 years. The children’s cognitive abilities were tested at the same time as the samples were taken.
Lead author Taranbir Singh says that 10- year-old children with more than 0.72 mg/L fluoride in their urine had lower cognitive abilities than children with less fluoride in their urine, with most pronounced associations for verbal reasoning skills and the ability to interpret and process sensory input.
These results are at odds with other, much larger and longer, Swedish studies and other research globally.
Another Uppsala study, from 2021, specifically looking at effects of fluoride in drinking water on IQ, followed 700,000 Swedish children through to adulthood, testing cognitive capacity with multiple IQ tests and school results, and subsequent adult income.
Sweden doesn’t add fluoride to drinking water, but natural levels vary from 0 to 4.1 mg/L, says lead author of the 2021 paper, Dr Linuz Aggeborn.
The study says children with higher fluoride intakes were more likely to find work as adults and achieved higher average incomes, because they had better teeth, and says there is no evidence that fluoride levels affected cognitive ability.
Fluoride is a natural element, common in water, food, soil and rocks. It has been added to Australian drinking water since the 1950’s, and “has been the cornerstone of dentistry and public health, owing to its ability to protect against tooth decay,” says Professor Loc Do of The University of Queensland’s School of Dentistry.
Similar results have been found in Australia, in a study using data from the 2012-2014 National Child Oral Health Study, with a follow-up in 2022-2023. Lead author, Do, says the research provided “consistent evidence that early childhood exposure to fluoride does not affect cognitive neurodevelopment.”
Dr Michael Foley, past-President of the Queensland Dental Association, says “It’s worthwhile having a cold shower and thinking logically. What about evidence on the ground?” he says.
He pointed out that Queensland children’s NAPLAN (National Assessment Program – Literacy and Numeracy) scores have increased since widespread fluoridation was introduced in 2008. “Children in fluoridated Townsville and Brisbane appear no different to children in non-fluoridated Cairns, Mackay and Rockhampton.”
“Singapore and Hong Kong also fluoridate their drinking water, and their children are often said to be among the smartest in the world.
“How could all this happen if fluoride adversely affected cognitive function. Does anyone truly believe that adults in the rest of Australia (largely fluoridated since the 1960s and 70s are dumber than adults in Queensland (largely non-fluoridated until 2008? Of course not. The idea is ludicrous.”
Not the first time fluoride research has raised eyebrows
