LETTER: Fluoride exposure link to reduced IQ among children

SIR – This month the findings of three important human epidemiological studies were published in peer reviewed scientific journals which have important and far reaching implications for this country. The first study published in the journal Environmental International by leading researchers in the United States, Canada and Mexico found that maternal fluoride exposure during pregnancy, as measured by urinary fluoride concentrations, was significantly associated with attention deficient disorders in offspring. 

This study is consistent with previous findings published in 2015 in the journal Environmental Health, which found that exposure to fluoridated water was associated with increased prevalence of ADHD in the United States. Furthermore, this current study supports the previous findings by the same authors published in September of 2017 in ‘Environmental Health Perspectives,’ which found that that maternal exposure to fluoride during pregnancy among women residing in Mexico City was associated with reduced IQ in offspring. 

Earlier this year, a further study by Professor Strunecka and colleagues published in Surgical Neurology International highlighted that fluoride exposure may also be associated with autism spectrum disorders.

The second study published this month, also in ‘Environmental Health Perspectives,’ found that maternal fluoride exposure among pregnant women in Canada was comparable to that found in pregnant women in Mexico City, which was associated with lower IQ in offspring. This study also found that community water fluoridation was the major source of fluoride exposure for pregnant women living in Canada. 

Finally, the third study published this month, also from Canada, found that among adults living in Canada who had moderate to severe iodide deficiency and higher exposure to fluoride were at increased risk of hypothyroidism. It is well recognised that iodine deficiency is a major public health problem in Ireland along with hypothyroidism. 

However, unlike Canada, 80% of dwellings in the Republic of Ireland are provided with artificially-fluoridated drinking water, compared to approximately 30% in Canada. Moreover, per capita consumption of tea (which contains high levels of fluoride) is three- to four-fold higher in Ireland than Canada. 

Tea beverages in Ireland are also invariably made with fluoridated tap water, along with coffee or any other beverage than requires water. 

Available evidence would therefore suggest that fluoride intake in the Republic of Ireland significantly exceeds that of Canada. 

Furthermore, as Mexico has the lowest per capita consumption of tea in the world, it is also predictable that fluoride intake among women in Ireland exceeds that reported among pregnant women in Mexico City. 

The persuasive evidence from these well controlled studies by leading international epidemiologists and environmental toxicologists linking maternal fluoride intake in pregnancy to lower IQ and ADHD would imply that the dramatic increase in ADHD prevalence witnessed in Ireland in recent decades may be causally associated with water fluoridation as well as uncontrolled fluoride intake from other sources such as tea. 

Worthy of note: while the Republic of Ireland has never undertaken national surveys to assess the prevalence of ADHD in its infant, adolescent or adult population, it has been documented that among children with intellectual disabilities the prevalence of ADHD has been reported to be an astounding 55.9% in the Republic of Ireland. Among adults attending psychiatric outpatient clinics, 33.8% have been reported to meet the criteria for childhood onset ADHD.

Collectively, these findings are consistent with the growing body of evidence that fluoride is both neurotoxic and an endocrine disruptor, and that early life exposure as well as long term exposure among adults is contributing to the burden of childhood neurological disorders and other diseases associated with hypothyroidism, which are highly prevalent in the Republic of Ireland. Moreover, these findings also suggest that fluoride exposure is also contributing to reduced IQ among children in Ireland.

Declan Waugh,

Environmental Scientist,

Doherty’s Road, 

Bandon.