Fluoride levels often below recommendation

The amount of fluoride added to Dunedin's tap water has been regularly dropping below Ministry of Health guidelines. Photo supplied.
The amount of fluoride added to Dunedin's tap water has been regularly dropping below Ministry of Health guidelines. Photo supplied.
The amount of fluoride being added to Dunedin's drinking water is regularly dropping below Ministry of Health guidelines, following a Dunedin City Council decision to lower the dose, it has been confirmed.

The revelation has prompted Cr Richard Thomson to call for a policy rethink, while Public Health South medical officer of health Dr Marion Poore warned, over time, it was possible more tooth decay could result.

''This means that the benefits of fluoridated water supply to the whole community are reduced,'' she said.

The council voted in May last year to reduce the amount of fluoride being added to the city's drinking water from 0.85mg per litre to 0.75mg per litre. The council had previously targeted 0.85mg per litre to ensure the dose administered fell within ministry guidelines, which recommended a range between 0.7mg per litre and 1mg per litre to protect against tooth decay.

However, council water production manager Gerard McCombie warned councillors at the time the change to the lower target could result in the actual dose dropping below the ministry's guidelines. That was because of inaccuracies in the delivery mechanism which meant the actual dose administered fluctuated each time, he said.

A majority of councillors voted to proceed anyway, urged on by Cr Kate Wilson, who suggested the change, and the switch to a lower dose was made days later.

Since then, the actual dose being administered had dropped below ministry guidelines 65 times, data released to the Otago Daily Times following an official information request showed.

That compared with just five misses in the first half of the year, before the change to a lower target was made.

Mr McCombie told the ODT trying to hit the lower target, rather than fall within the range, was ''a bit like trying to hit the bullseye with every dart''.

''Sometimes, we're a bit above it, but quite a bit of the time we are below it,'' he said.

As a result, council staff were reviewing the entire dose system to try to improve accuracy, although absolute accuracy would be ''impossible to guarantee'', he said.

Cr Wilson defended the decision to lower the dose, saying councillors wanted to set it, rather than leave it up to staff.

They also wanted to take a ''conservative'' approach, given public concern, including about the health of infants consuming fluoridated water with powdered baby formula, she said.

She was also surprised council staff had not reported the problem to councillors, or adjusted their sights.

''I'm not quite sure why it is so flexible. I think if you're targeting 0.75 and you're finding you're getting a whole lot of readings below 0.7, then you should be aiming higher.

''That's what the idea of a target is.''

However, she conceded regularly missing the target was ''something we may need to address''.

''If we're not hitting that, I'm very happy to open the debate again.''

Cr Thomson - also a Southern District Health Board member - said the decision to lower the dose had been made ''on the hoof'', and the council now needed to rethink its approach.

He did not know if the repeated misses - sometimes for more than a week on end - raised public health concerns, but said that was the ''fundamental question''.

''Does it matter? And, if it does, then in my view, we need to have another look at it.''

Fluoride was added to 85% of the city's drinking water - at the Mt Grand and Southern water treatment plants - and had been credited by health authorities with reducing levels of tooth decay.

However, opponents have mounted repeated campaigns to end ''mass medication'', citing a variety of health concerns. The council received 34 public submissions on fluoride at its last annual plan budget hearing, the most on a single subject.

Dr Poore said the ministry's recommendations aimed to reduce tooth decay for the whole community.

''Tooth decay is the most common chronic disease in our community and causes misery ... loss of a smile, painful infections, requirement for dental procedures, time off work and school.

''It makes sense to add fluoride to community water supplies in a way that the recommended levels are reached consistently - do it properly to get the most benefit,'' she said.

However, she acknowledged there could be ''challenges'' maintaining exact levels.

- chris.morris@odt.co.nz



Children with severe dental caries had statistically significantly lower numbers of lesions if they lived in a fluoridated area. The lower treatment need in such high-risk children has important implications for publicly-funded dental care.

--Community Dent Health. 2013 Mar;30(1):15-8.
Fluoridation and dental caries severity in young children treated under general anaesthesia: an analysis of treatment records in a 10-year case series.
Kamel MS, Thomson WM, Drummond BK.
Department of Oral Sciences, Sir John Walsh Research Institute, School of Dentistry, The University of Otago, Dunedin, New Zealand.

Adverse reactions

Adverse reactions to fluoridated water or supplemented fluoride are well documented in the medical literature. (Waldbott, Feltman and Kosel, Grimbergen and the Physicians Desk Reference). Many people don't know fluoride is causing their health problems. They go to their doctor who also doesn't suspect fluoride and end up taking medications to alleviate side effects. Bottle-fed babies exceed the upper limit of fluoride intake. It would be best if those who want to supplement with extra fluoride do so themselves, just like every other supplement.

Optimally fluoridated water

Optimally fluoridated water (fluoridated) is:

Safe: It causes no adverse health effects in anyone at optimal levels.

Effective: It provides 25% or greater cavity reductions over a person's lifetime simply by drinking the water. It requires no change in a person's behaviour to impart its benefits

Cost Saving: It's cheap and cost effective. For every $1 spent on water fluoridation, $38 in dental treatment costs are avoided.

So really just adjust the levels to the optimum for good tooth repair

Prevents dental disease. It is the most efficient way to prevent one of the most common childhood diseases - dental decay. An estimated 51 million school hours are lost each year due to dental-related illness.

Gift, H.C. "Oral Health Outcomes Research: Challenges and Opportunities." In Slade, G.D., ed., Measuring Oral Health and Quality of Life. Chapel Hill, NC: Department of Dental Ecology, University of North Carolina 1997;25-46.

Protects all ages against cavities. Studies show that community water fluoridation prevents at least 25 percent of tooth decay in children and adults, even in an era with widespread availability of fluoride from other sources, such as fluoride toothpaste.

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