February 24, 2015
1 min read

Fluoridated water contributes to increased rates of hypothyroidism

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A 30% higher rate of hypothyroidism in England is linked to water fluoridation levels greater than 0.3 mg/L, according to study findings published in the Journal of Epidemiology & Community Health.

According to the researchers, 10% of England’s population lives in areas with naturally or artificially fluoridated water supplies of 1 mg/L.

“In areas where there are higher levels of fluoride [clinicians] need to be aware that more people could be suffering from hypothyroidism,” Stephen Peckham, BSc, MA, of the Centre for Health Service Studies at the University of Kent, told Endocrine Today. “For public health authorities the key message is that non-ingested approaches to using fluoride to tackle dental caries should be considered.”

Stephen Peckham

Stephen Peckham

Peckham and colleagues evaluated data from the Drinking Water Inspectorate for 2012 levels of fluoride in community drinking water supplies and from 2012 to 2013 national quality and incentive scheme returns for cases of hypothyroidism diagnosed by 7,935 general practices in England. The researchers geographically mapped hypothyroidism rates against fluoridation areas.

A secondary analysis was conducted in two areas — West Midlands, which was supplied with fluoridated drinking water, and Greater Manchester, which was not.

Higher than expected rates of hypothyroidism were found in areas with fluoride levels greater than 0.7 mg/L compared with areas with lower levels.

Similarly, twice as high rates of hypothyroidism were reported in the West Midlands compared with Greater Manchester.

“While diagnosed hypothyroidism can be well controlled by taking thyroid supplements, there are a number of health problems associated with undetected subclinical hypothyroidism and undiagnosed hypothyroidism where symptoms associated with hypothyroidism are observed but not attributed to thyroid dysfunction,” the researchers wrote. “In many areas of the world, hypothyroidism is a major health concern and in addition to other factors — such as iodine deficiency — fluoride exposure should be considered as a contributing factor. This study suggests that in fluoridated areas, testing for hypothyroidism should be routinely considered where any symptom attributable to lowered thyroid function is observed.” – by Amber Cox

For more information:

Stephen Peckham, BSc, MA, can be reached at Centre for Health Services Studies, University of Kent Canterbury, Kent CT2 7NF, UK; email: s.peckham@kent.ac.uk.

Disclosure: Peckham reports involvement in a campaign to prevent fluoridation of drinking water supplies.