From Volume 50, Issue 6, June 2023 | Pages 479-481
With passage of the 2022 Health and Care Act, the legislation governing water fluoridation in England has changed. This article provides an overview of the changes and implications for decision-making in relation to this important public health measure and an overview of the evidence base.
Fluoride in the water supply and the active process of water fluoridation are separate, but related issues, both being extensively covered by legislation to protect the public and define the powers of public bodies. Legislation in relation to water fluoridation has undergone several changes since the first specific primary legislation in the form of an act of parliament in 1985,1 reflecting either changes to how the water industry relates to the issue, or changes to the health sector.
Fluoride is naturally present in drinking water and, like other aspects of water quality, is governed by water quality standards. These are set out in secondary legislation and the relevant regulations in England are the 2016 Water Supply (Water Quality) Regulations,2 as amended, which describe how the quality of drinking water is to be monitored. Schedule 1 to these regulations sets out the required parameters for a range of water quality measures, including fluoride levels. The maximum level of fluoride permissible (prescribed concentration or value) is 1.5 mg/L, this reflecting WHO guidance,3 and designed to be protective against any ill effects over a lifetime of consumption, including dental fluorosis, which might be unsightly. Compliance with these standards is governed in England by the Drinking Water Inspectorate (DWI). The analogous regulatory limit in the USA is 4 mg/L, although there is a voluntary limit of 2 mg/L, whereas the target concentration for US fluoridation schemes is 0.7 mg/L.
Private water supplies in England are also subject to regulations,4 which set the same standards for fluoride levels, although compliance is governed by local authorities. Natural mineral water is subject to separate regulations,5 which (Schedule 6) allow for up to 5 mg/L, a concentration similar to that seen in a cup of tea. Like private water supplies, this is governed by local authorities.
This legislation is important in understanding the wider context of community water fluoridation (CWF), since some water sources in England naturally contain fluoride at levels that might exceed the 1.5 mg/L standard, whereas others may naturally contain fluoride concentrations that are higher than the 1.0 mg/L target concentration for CWF, but within the overall permitted level. If there are concerns that fluoride in drinking water at the levels currently permitted in legislation are harmful, then this is primarily an issue for the above water quality standards. To put it simply, it might be straightforward to tell water companies to cease fluoridation with immediate effect, but finding alternative water supplies for those served by naturally fluoridated sources would be another matter. Those opposed to fluoridation on the basis of assertions of harm never seem to demand that places like Hartlepool should be evacuated, or that people should stop drinking tea with similar urgency, yet these would need to be parallel considerations.
The legislative basis of CWF currently comes from the 1991 Water Industry Act6 as amended. The 2012 Health and Social Care Act amended the 1991 Act, with effect from April 2013, to separate the running of existing schemes from the power to make decisions about schemes, the former transferring from the NHS to the Secretary of State for Health and Social Care, the latter to local authorities. The 2022 Health and Care Act7 further amended the 1991 Act to consolidate these powers and responsibilities under the Secretary of State. Secondary legislation, in the form of the 2022 consultation regulations,8 sets out the process for public consultation where new schemes are to be established, or existing ones varied or terminated. Taken together the Act and Regulations allow the Secretary of State to instruct water companies to fluoridate water supplies and to reimburse them for the costs they incur in doing so, but places a duty on the Secretary of State to undertake public consultation in defined circumstances.
The 1991 Act, as amended, also sets the target fluoride concentration for schemes, and the chemical compounds that can be used. It also requires the Secretary of State to monitor the health of populations served by water fluoridation schemes and to report at no less than 4-yearly intervals. Finally, the DWI has issued a code of practice9 for the water industry that sets out the technical processes to be followed in operating schemes.
In summary, the combined effect of legislation and guidance sets out the powers and responsibilities of the commissioners and providers of water fluoridation schemes, including limits on fluoride levels, requirements for public consultation and reporting of health effects. The wider water quality legislation covers all fluoride content of drinking water, whether present naturally or as the result of a fluoridation scheme. Community water fluoridation sits within the wider context of water quality.
Individual papers in the scientific literature may vary in quality, and even apparently high-quality research can occasionally produce results that are later shown to be incorrect. For these reasons it is preferable to pay more attention to authoritative reviews of the wider evidence base rather than individual papers and, for the latter, to await peer review by the wider scientific community. Time and again newly published research is accompanied by press releases from the authors' institutions and media commentary which, on further analysis, have overstated the results.
Perhaps reflecting the political contentiousness of CWF, there have been several authoritative reviews of the scientific literature in recent years. Public Health England summarized these in their 2021 updated fluoridation toolkit,10 although this is unlikely to be updated further in its 2021 form owing to the 2022 changes in legislation. Since that update, there has been a further review published by the New Zealand government.11 The consistent conclusion of these reviews is that water fluoridation is effective in reducing levels of tooth decay in the populations and is not associated with harms to health.
As required by the 1991 Act, monitoring of the health effects of water fluoridation in England takes place every 4 years, and three reports have been published since 2014.12–14 These reports have produced findings that are consistent with the conclusions of the evidence reviews that water fluoridation is a safe and effective public health measure.
Those who follow the history of water fluoridation will know that it has been associated with repeated assertions of harm to aspects of general health, although the exact harm tends to vary. In the 1990s, a common assertion related to bone cancer. More recently, the assertions have centred on thyroid and neurological effects. While these newer assertions have been addressed in the reviews mentioned above, there have also been recent evidence reviews15–17 focusing on neurological effects, which have not changed the conclusions of the wider evidence reviews. There has also been a summary of the issue in the 2022 health monitoring report.14 At the time of writing, a review of developmental neurotoxicity in relation to fluoride has been published in draft form by the US Department of Health and Human Services National Toxicity Program, and this is currently under review by that body's scientific advisory board.18
In summary the global scientific consensus is that water fluoridation is an effective and safe public health measure.
