8: Teeth and Fluoridation
List
of Tables
List
of Figures
Main Body
1: Boundaries
and Populations
2: Inequalities
and Deprivation
3: Ethnicity
and Health
4: Environmental
Hazards
5: Health
related behaviour
of
young people
6: Accidents
7: Cancer
8: Teeth and fluoridation
9: Coronary
Heart Disease
10: Communicable
diseases
8.1 The 'debate' on fluoridation
Despite overwhelming evidence that fluoride protects against dental caries, less than 10% of the population of England and Wales receives fluoridated water (Coggon and Cooper, 1999). The West Midlands is the most extensively fluoridated region with around 3.5 million people receiving treated water supplies (table 8.1 and figure 8.1). The Government has recently announced a new expert review of fluoride and health with a view to extending fluoridation (Department of Health, 1999). This is partly a response to continuing opposition to fluoridation from a minority who regard the intervention as hazardous, unjustified and unethical. Although improvements in diet and the introduction of fluoride toothpaste have improved general dental health, fluoridated water still has important benefits particularly in poorer populations (Jones et al 1997). However, campaigners against fluoridation have raised a number of claims of harmful effects and in particular cancer, immune system effects, osteoporosis and dental fluorosis.
Claims were raised in the late 1970s that fluoridated water was linked to increases in cancer mortality, particularly bone and oral cancers. However, epidemiological evidence does not support the view that fluoridated water increases the risk of developing cancer (Cook-Mozaffari, 1999; Kleerekoper, 1994). Only the work of active campaigners against water fluoridation has linked fluoridated water and cancer but this work has been repeatedly criticised (Cook-Mozaffari, 1999). There have also been claims that consumption of fluoridated water has a deleterious effect on the immune system. A major review of the available data on this subject concluded that at the concentrations expected from fluoridated water, there was no detectable effect. Furthermore, no evidence has yet been reported of any deleterious effect on specific immunity and there have been no confirmed reports of allergic reactions to fluoridated water. The British Society for Allergy and Clinical Immunology has stated that "there is absolutely no evidence that fluoride at levels found in water interferes with the immune function" (Lawrence, 1993).
There is no convincing evidence of an effect on bone fractures where most of the reports are from ecological studies of hip fractures and an ongoing analysis of a case-control study has so far found no evidence of increased risk (Coggon and Cooper, 1999).
Table 8.1 Percentage of Health Authorities supplied with fluoridated water
Figure
8.1 Map of fluoridated Water Supply Zones West Midlands 1998
Dental fluorosis is the most common adverse effect of water fluoridation. It is caused by high tissue fluoride concentrations from excessive fluoride ingestion during tooth formation and results in hypomineralisation of the dental enamel (Simko, 1997). It is a dose response condition. Consequently the severity ranges from the barely discernible, even to a trained observer, through to the most severe manifestations such as stained, pitted or brittle teeth. A high prevalence of mild dental fluorosis has been reported for many fluoridated areas. Dental fluorosis has been taken up by campaigners against water fluoridation to support their concerns. However, other sources of fluoride especially dental products may also play a significant role in dental fluorosis. The reported increase in dental fluorosis in populations with fluoridated water has also been found to be associated with use of fluoridated dentifrices, fluoride supplements, infant formula, fluoridated drinks, juices prepared with fluoridated water and other commercially prepared beverages. The importance of these other fluoride sources is demonstrated by reported increases in dental fluorosis in communities with unfluoridated water (Simko, 1997).
A major survey of child dental health in the region was conducted during 1997 and 1998, involving 1,358 of the region's schools (78%) and the examination of over 40,000 children (91%) at five years old. This survey has shown that children from schools in totally or largely fluoridated areas (Birmingham, Coventry, Dudley, Solihull, Wolverhampton, Sandwell, Walsall, Warwickshire, South Staffordshire and Worcestershire) had better dental health than those in non-fluoridated areas (North Staffordshire, Herefordshire and Shropshire). Figure 8.2 shows the percentage of children with some decayed, missing or filled teeth by Health Authority.
Figure
8.2 Children's Dental Decay and Fluoridation
8.2 West Midlands public opinion on, and knowledge of, fluoridation of the water supply
The West Midlands Regional Health and Lifestyle Survey 1995 was the first large-scale survey of its kind in the West Midlands. It included two questions on fluoridation of the water supply:
- Fluoride is a substance added to toothpaste and sometimes to the water supply to prevent tooth decay. As far as you know, does your water supply at home have fluoride added to it?
- Do you think fluoride should be added to the water supply?
The survey was designed by MORI in conjunction with the West Midlands Regional Health Authority and the Regional Lifestyle Steering Group, and the fieldwork was carried out by MORI. The sample of 54,716 people was sufficiently large to have a margin of error of + or - 3% at both district and regional levels. Thus percentage differences reported here of greater than 3 percent are statistically significant and not chance findings. Weighted information is used, so that statistics accurately reflect the composition of the region's population. The maps use information at the electoral ward level, but where the sample size was less than 70, adjacent wards data have been combined.
8.2.1 Knowledge of fluoridation of household water supply
Figure 8.3 shows whether people thought their household water supply was fluoridated, and can be compared with Figure 8.1 which shows which areas of the West Midlands actually have fluoridated water supplies. Full information on whether respondents thought their water supplies at home had fluoride added to it is shown by health authority in Figure 8.4. A large minority, 39% did not know whether their water was fluoridated. In addition sometimes substantial minorities incorrectly believed that their water was fluoridated or was not fluoridated. For example, in Hereford and Shropshire, districts that do not have fluoridated water, 38% and 46% respectively, wrongly thought that their water supply contained added fluoride.
Figure
8.3 % of respondents who believed their home water supply was fluoridated
Young people were most likely to say that they did not to know whether the water supply was fluoridated (50% of 16 to 24 year olds and 46% of 25 to 34 year olds said this). This includes those most likely to live in households with young children where the dental health gains from the use of fluoride are greatest. More women (42%) than men (36%) said that they did not know whether their water supply was fluoridated. Ethnic minorities were more likely not to know if their water was fluoridated: 55% of Afro-Caribbeans, 63% of Asians and 45% of other ethnic minorities did not know this.
8.2.2 Public opinion on whether fluoride should be added to the water supply
A clear majority of the survey respondents, 52%, thought that fluoride should be added to the water supply, 17% thought that it should not be added and 31% did not know whether it should be added.
Men were more likely than women to think fluoride should be added to the water supply (54% compared with 50%), while more women were uncertain (18% of men compared with 34% of women) (Figure 8.5). Support for fluoridation was greatest among 16 to 24 year olds (58%) and least among the over 75s (36%) (Figure 8.6). Comparable proportions of white (52%) , Afro-Caribbean (51%) and Asian (53%) ethnic groups supported fluoridation, but only 47% of other ethnic minorities did so . Fewer white people (31%) than other ethnic minorities said they did not know whether they supported fluoridation, and a higher percentage (18%) opposed fluoridation. People living in the most deprived areas (classified by Townsend score) were most likely to say they did not know whether the water supply should be fluoridated (34% in the most deprived areas, 28% in the least deprived) (Figure 8.7). Support for fluoridation was highest in the most affluent areas (55%).
Support for fluoridation was therefore highest at 62% in the affluent and fluoridated health district, Solihull (Figure 8.4). It was lowest in Hereford (46%), Shropshire (45%) and North Staffordshire (46%) which do not have fluoridated water supplies. Even in these areas twice as many people supported fluoridation as opposed it.
Figure
8.5 "Do you think that fluoride should be added to the water
supply?" Response by sex.
Figure
8.6 "Do you think that fluoride should be added to the water
supply?" Response by age.
REFERENCES
Coggon, D. and Cooper, C. (1999) Fluoridation of water supplies. British Medical Journal 319, 269-270.
Cook-Mozaffari, P. (1999) Cancer and fluoridation. Community Dental Health 13, 56- 62.
Department of Health (1999) Reducing health inequalities: an action report. London: Department of Health.
Jones, C., Taylor, G., Whittle, J., Evans, D. and Trotter, D. (1997) Water fluoridation, tooth decay in five year olds, and social deprivation measured by the Jarman score: analysis of data from British dental surveys. British Medical Journal 315, 514-517.
Kleerekoper, P. (1994) Non-dental tissue effects of fluoride. Advances in Dental Research 8, 32-38.
Lawrence, A. (1993) Safety and effectiveness of fluoridation. British Dental Journal 198-199.
Simko, L. (1997) Water fluoridation: Time to re-examine the issue. Paediatric Nursing 23, 155-159.
For more information please contact Carol Richards
© Department of Public Health and Epidemiology, University of Birmingham