Very good fluoridation political call, Dr Verrall

Infectious diseases specialist Dr Ayesha Verrall was a surprise cabinet appointment being a first-time MP. Despite the rarity she’s not mucking around. This is evidenced by her legislative proposal, as Associate Minister of Health, to shift decision-making over water fluoridation from local authorities to the Director-General of Health (in effect the Ministry of Health).

The issues behind Verrall’s initiative are nicely discussed in an ‘explainer’ article (20 March) by Stuff journalist Hannah Martin (

When working for the Association of Salaried Medical Specialists I would often come across despair and frustration from specialists discussing gut-wrenching cases of poor tooth decay. This wasn’t just dental and public health specialists. They also included those in emergency departments where these cases often presented themselves and anaesthetists where surgery was required (the latter also play an important role pre and post-operative care).

What is fluoridation

Fluoride is a mineral found in our bones and teeth. It also naturally exists in water, soil, plants, rocks, air and many foods. Fluoride makes teeth more resistant to decay by strengthening the tooth surface. It also interferes with the growth of cavity-causing bacteria and helps repair the early stages of tooth decay. But there is not enough fluoride in water and food to help prevent tooth decay.

Consequently fluoridation is the process used to adjust the level of fluoride in drinking water, consistent with World Health Organisation safety advice, to achieve prevention. All of us on reticulated supply drink fluoridated water but not all at a level to address tooth decay.

Fluoridation first began in New Zealand in 1955. Around 50% of New Zealanders presently receive fluoridated water (about 60% of those on reticulated water supplies). Reportedly only one-third of local authorities have authorised fluoridation. This apparently discrepancy is reflected in the fact that most of Auckland with a single council is fluoridated.


The most recent New Zealand oral health study, conducted in 2009, revealed that there was 40% less tooth decay among children and adolescents where water was fluoridated compared with those where it wasn’t. Fluoridation isn’t a magic bullet for preventing tooth decay. But, along with brushing twice daily, eating healthy foods and regular dental check-ups, it is the most effective.

Water fluoridation is also cost effective according to experts. This expertise was reinforced by a 2015 Sapere Research Group study which concluded that for every dollar spent on water fluoridation, $9 is saved in dental care costs, some in the health system but largely by individuals.

There are genuinely held concerns over fluoridation believing that it causes or contributes to a number of health conditions such as cancer, Down’s syndrome, renal disease, allergic conditions, repetition strain injury, and that it causes interference with enzyme function. But they haven’t been substantiated by experimental studies or epidemiological analyses.

It is true that if consumed in large amounts fluoride can be toxic. But, according to the Health Ministry, a person would need to drink thousands of glasses of water in a single sitting to obtain anything near a lethal dose (and an awful amount peeing I might add).

Verrall proposal

The Associate Health Minister is using a less known but acceptable legislative means to achieve her objective. She is amending the stalled Health (Fluoridation of Drinking Water) Amendment Bill introduced by the National Party to transfer decision-making on water fluoridation from local authorities to district health boards.

There was good sense behind National’s bill but Verrall is improving its efficiency by centralising decision-making through transferring the responsibility to the Director-General of Health. Her mechanism will be by means of what is called a Supplementary Order Paper.

National Party concerns

National is concerned. While agreeing with the science behind fluoridation, its Deputy Leader and health spokesperson Dr Shane Reti​ has called it an “overreach” worried that the centralisation of power would stir up more resentment by those who are against fluoridation. He makes a reasonable point but there are at least four counters.

First, the scientific evidence about the benefits (and risks) of fluoridation is overwhelming. The public accepted that the Government was following the best available science in its Covid-19 elimination of community transmission strategy. Providing that the science behind fluoridation is communicated as effectively as it was over Covid-19, there is no reason why the public wouldn’t similarly accept it, particularly if it focusses on those who might be understandably hesitant.

Second, it will be important that the Associate Minister ensures that there is plenty of opportunity for the public to make submissions that are then considered by Parliament’s relevant select committee. Third, the logic behind decentralising fluoridation decisions to DHBs is about as consistent as doing the same with decisions over which Covid-19 vaccines should be purchased.

Finally, increased resentfulness from already aggressive opponents should not be allowed to govern what we do. That resentfulness would exist regardless of who make the decision. Just imagine how much less the progress in combating homophobia would be if those behind the homosexual law reform bill of 1986 had backed down in fear of making more resentful the bill’s vociferous opposition.

Social determinants of health

Social determinants of health are both external to our health system and the biggest driver of poor health. Serious tooth decay is driven by social determinants. Safely adjusting the level of fluoridation doesn’t address the causes of social determinants of health but should go a long way to reducing bad oral health consequences.

It is overstating to say that Ayesha Verrall is brave to promote this initiative although she is likely to be subjected to personal abusive attacks from some fanatical quarters. But, as a first-time MP cabinet member, she has made an early astute political call that if legislated should make a positive difference in the lives of many (perhaps even transformational).

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