Fluoridation: the north-south divide comes into focus
The Water (Fluoridation) (Northern Ireland) Order 1987 gave health boards the power – with the approval of the then Department of Health and Social Services – to increase the fluoride content of the water supplied within the area of their jurisdiction. In the more than 30 years since that power was afforded to boards, not one has established and maintained a policy of fluoridation of the water supply.
Thirty years early, in Dublin, the ‘Fluorine Consultative Council’ convened for the first of 15 meetings, culminating in its recommendation in the summer of 1958 to the Republic’s Minister for Health, Sean McEntee, that the public water supply should be fluoridated. Despite a legal challenge from the wife of the secretary of the Soil Association, the Government pressed ahead with its plans; crucially opting to use mandatory, rather than enabling, legislation which avoided the potential for some areas of the country to fluoridate and others to not.
Water fluoridation was introduced to Dublin City in July 1964, and Cork City in May 1965. By 1970 most of the major cities and towns in the Republic had fluoridated water supplies and today 71 per cent of people in Ireland have access to fluoridated water supplies. Between 1961 and 1963, a baseline national caries study had been conducted; representative samples of five to 16-year-olds were examined in each of the 26 counties in the Republic of Ireland. High caries levels were recorded; for example, the mean decayed/missing/filled teeth (DMFT) for 15-year-old children was 8.2.
To comply with the Health (Fluoridation of Water Supplies) Act 1960, the Department of Health established a unit at University Dental School, Cork, in 1965 which conducted studies on dental caries and fluoride in the late ‘60s and early ‘70s. For example, a survey of a random sample of four- to 11-year-old school children in Cork City in 1969 showed that caries levels among children were substantially lower than those recorded in the 1961 baseline study.
A national survey of children’s dental health in 1984 showed a substantial decline in the prevalence of dental caries both in fluoridated and non-fluoridated communities, and the reduction was considerably greater in the fluoridated communities. This survey also captured levels of fluorosis; 94 per cent of children in fully fluoridated communities had normal enamel, according to Dean’s Index, compared with 98 per cent in non-fluoridated communities.
In 2002, a ‘north-south’ survey showed a substantial decline from 1984 in dental caries in both fluoridated and non-fluoridated communities in the Republic of Ireland, and in the non-fluoridated population of Northern Ireland. However, the decline was substantially greater in the fluoridated communities. The prevalence of dental fluorosis increased substantially in the Republic of Ireland between 1984 and 2002, particularly in lifetime residents of fluoridated communities, prompting the Government to approve a reduction in the level of fluoride added to the water supplies and the introduction of guidance to reduce the ingestion of fluoride toothpaste in early childhood.
Ireland’s Expert Body on Fluorides and Health “is of the opinion that there continues to be overwhelming evidence that water fluoridation significantly benefits dental health. The Expert Body is satisfied, having studied current peer reviewed scientific evidence worldwide, that water fluoridation, at the optimal level, does not cause any ill effects and continues to be safe and effective in protecting oral health of all age groups.”
In January this year, researchers at Manchester University noted that “the most fundamental component of any population-wide caries-prevention strategy is sugar reduction through the use of upstream policy levers. Reducing the underlying cause of disease through the restoration of normality, rather than adding a protective factor, is a more radical approach, and does not come with the risk of unwanted effects such as dental fluorosis.” However, they concluded, “with any highly prevalent chronic disease, the social and biological causal pathways involved are complex and action at multiple levels is required. Fluoride is highly effective at preventing caries and its use over the last 50 years has transformed dental health.”1 With the UK Government having announced its intention to take control over the decision of whether to fluoridate the water supply away from local authorities, the position of the Northern Ireland Executive will quite rightly come into sharp focus.
1. Moore, D., Allen, T., Birch, S. et al. How effective and cost-effective is water fluoridation for adults? Protocol for a 10-year retrospective cohort study. BDJ Open 7, 3 (2021). https://doi.org/10.1038/s41405-021-00062-9