Water Fluoridation in New Plymouth. Dr Greg Simmons BHB, MBChB, Dip Obst, FRNZCGP, MPH, FAFPHM, FNZCPHM Medical Officer of Health

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1 Water Fluoridation in New Plymouth Dr Greg Simmons BHB, MBChB, Dip Obst, FRNZCGP, MPH, FAFPHM, FNZCPHM Medical Officer of Health

2 Presentation will Cover What water fluoridation is How water fluoridation works and its effectiveness Health concerns raised about fluoridation Ethics of water fluoridation Effects of stopping fluoride supplementation The inequalities in oral health

3 Key Messages Water fluoridation is an effective strategy especially for those at risk of poorer oral health outcomes The benefits outweigh any potential risks Likely to be a net reduction in oral health and an increase in dental treatment costs if fluoridation discontinued Recommend continued water fluoridation and its introduction to populations of 1000 or greater Scientific evidence of potential harm and benefits should continue to be monitored

4 Common Terms ppm MAV Dental caries DMFT/dmft or DMFS/dmfs Percent caries free parts per million also sometimes mg/l maximum acceptable value tooth decay, dental decay decayed, missing and filled teeth or surfaces the proportion of people without tooth decay

5 Community Oral Health Water Fluoridation Fluoride toothpaste Diet and lifestyle Professional care and treatment

6 Water Fluoridation The process of supplementing the level of fluoride in drinking water to between 0.7 and 1.0 ppm Hydrofluorosilicic acid (HFA) Maximum acceptable value of fluoride in drinking water 1.5 ppm (NZ Drinking Water Standards 2005) Commenced in NZ almost 60 years ago About half of NZ s population have fluoridated drinking water

7 What is Fluoride? 13th most common element on earth Found in all water and soils Sea water: ppm Fluoride deficient water: ppm Fluoridated water: ppm Natural Fluoride rich water: ppm

8 Natural Fluoride in Water in Taranaki Normal to find low levels of fluoride in drinking water Patea ppm 1 Waverley ppm 1 Eltham 0.06 ppm 1 New Plymouth 0.05 ppm 2 Source: 1 Taranaki Public Health Service 2 New Plymouth District Council

9 Fluoride Levels in the NPDC Water Supply Fluoride Concentration in NP Water Supply /07/ /07/2010 4/08/ /08/2010 1/09/ /09/ /09/ /10/ /10/ /11/ /11/2010 8/12/ /12/2010 5/01/ /01/2011 2/02/ /02/2011 2/03/ /03/ /03/ /04/ /04/ /05/ /05/2011 Fluoride concentration (ppm) 8/06/ /06/2011 Source: Water Information NZ Database Date of Sample

10 Enamel Dentine Plaque acids Ca 2+ PO 4 3- F - Tooth decay and the role of fluoride

11 Non-Maori & Maori Children Aged 9-13 Years Caries Free , New Plymouth District n= n= non-m aori So urce: T D HB C o mmunit y Oral Healt h Service Ethnicity M aori

12 DMFS 12 yr-olds: Wellington/Christchurch By Fluoride Status and Demographic Background (Lee & Dennison, 2004) N = DMFS Totals Maori Pacific Other Low Medium High Ethnic Group Fluoride Non-Fluoride SES Background

13 Nuffield Council on Bioethics Adding anything to the water supply should not be ruled out, if it may bring health benefits. The acceptability should be considered in relation to: (i) Balance of risks and benefits (ii) Potential for alternatives (iii) Role of consent where there are potential harms Rely on democratic decision-making procedures at the local and regional level because the need for, and perception of, water fluoridation varies between areas.

14 Individual Autonomy and Ethics Fluoridation as population-based disease prevention strategy compare drinking water chlorination Health promotion strategies are most effective when the public need to make little behaviour change Public good versus individual autonomy compare the wearing of seat belts or smokefree legislation

15 Assessment of Health Effects? Lots of reports Lots of claims Dental fluorosis Bone fractures Cancer IQ and brain function Thyroid effects Pineal effects

16 York Report 2000 Ten authors, systematic review, 214 studies There is no clear association of hip fracture with water fluoridation. The evidence on other fractures is similar. Overall, no clear association between water fluoridation and incidence or mortality of bone cancers, thyroid cancer or all cancers was found.

17 Cancer - Osteosarcoma No clear association between water fluoridation and osteosarcoma. (York Review 2000) Further research results awaited. Assessing fluoride as a risk factor for osteosarcoma is complicated by the rarity of the disease and that population is all generally exposed to some level of fluoride. (National Research Council 2006) Noted a US study showing an association in young males. Shortcomings in their study mean the results should be interpreted with caution pending publication of the larger study results. Co-investigators of Bassin point out that they have not been able to replicate these findings in the broader Harvard study, that included prospective cases from the same 11 hospitals. (NHMRC 2007) A possible link between fluoride in drinking water and osteosarcoma, but studies are equivocal. No evidence from animal studies to support the link, and thus fluoride cannot be classified as to its carcinogenicity. (SCHER 2010)

18 Osteosarcoma New Zealand average cases per year males years 2.4 cases per year males years Expect one case of osteosarcoma in New Plymouth District every: 35 years in males years 16 years in males aged years

19 Bassin et al s Conclusion Our exploratory analysis found an association between fluoride exposure in drinking water during childhood and the incidence of osteosarcoma among males but not consistently among females. Further research is required to confirm or refute this observation. Source: Bassin E, et al. Age-specific fluoride exposure in drinking water and osteosarcoma (United States)

20 Bone Fractures No clear association of hip fracture with water fluoridation. The evidence on other fractures is similar. (York Review 2000) Evidence that under certain conditions fluoride can weaken bone and increase the risk of fractures. Lifetime exposure to fluoride in drinking water at 4mg/l is likely to increase fracture rates compared with exposure at 1mg/l. (National Research Council 2006) Water fluoridation at levels aimed at preventing caries has little effect on fracture risk protective or deleterious. (NHMRC 2007) The occurrence of endemic skeletal fluorosis has not been reported in EU. (SCHER 2010)

21 IQ and Brain Function Insufficient evidence on any particular outcome to permit confident conclusions. (York Review 2000) A few studies of Chinese populations have reported IQ deficits in children exposed to fluoride at 2.5 mg to 4 mg/l in drinking water. The studies lacked sufficient detail to fully assess their quality and relevance to US populations. The consistency of the results appears significant enough to warrant additional research on the effects of fluoride on intelligence. (National Research Council 2006) The additional studies do not suggest an increased risk of other adverse events with the level of fluoridation used in Australia (~1 ppm). (NHMRC 2007) Limited animal data cannot support the link between fluoride exposure and neurotoxicity, noted in the epidemiological studies, at relevant non-toxic doses. SCHER agrees that there is not enough evidence to conclude that fluoride in drinking water may impair IQ. (SCHER 2010)

22 Conclusions Water fluoridation is an effective strategy especially for those at risk of poorer oral health outcomes The benefits outweigh any potential risks Likely to be a net reduction in oral health and an increase in dental treatment costs if fluoridation discontinued Recommend continued water fluoridation and its introduction to populations of 1000 or greater Scientific evidence of potential harm and benefits should continue to be monitored