4. Are there any reasons for concern about people’s fluoride intake? If so, who is at risk?
Most fluorides in rock and soil are insoluble. Some soluble fluoride is found in ground and surface water. Levels of naturally occurring fluoride in drinking water vary widely between and within EU member states.
Surveys suggest that in Europe adult consumption of tap-water and drinks containing water varies by a factor of five. Data on children’s consumption is sparse.
Bottled mineral water commonly has higher fluoride levels than artificially fluoridated drinking water, but should not exceed 5mg/L of fluoride. Consumption of mineral water also varies widely.
Fluoride intake in food is low, unless its preparation uses fluoridated water or salt. Tea-drinkers may take in more fluoride, depending on their choice of tea. There are no new EU data on fluoride in food. The EFSA used German background exposure from food based on intake of milk, meat, fish, eggs, cereals, vegetables, potatoes and fruit. This assessment gave fluoride intakes of 0.042, 0.114, and 0120 mg/day for young children, older children and adults.
The other main fluoride intake is from toothpaste, mouthwashes and dental gels, which may contain up to 1500 mg/L of fluoride. Assessing how much fluoride intake follows is difficult as it depends on assumptions about how much toothpaste is spat out again, and how much is swallowed, and whether people use the right amount when they brush. A full brush load has around three times as much toothpaste as the recommended “pea-sized” amount. Adults probably swallow around 10 per cent of what they squeeze onto their toothbrush. Most children have got their swallowing down to this level by the age of 8, but younger children tend to swallow much more, up to 48 per cent in 2-3 year-olds.
There are also contributions, in some cases, from prescribed fluoride supplements, and from dietary supplements and fluoridated salts.
The SCHER pulled all these estimates together to compile scenarios for total exposure to fluoride from all sources. These substitute for precise population measurements, and take account of what we know of concentrations in drinking water in different regions, food and drink consumption, toothpaste use, and so on. The scenarios were used to identify who might be at risk of exceeding the tolerable fluoride dose.
For example, for adults and children over 15, the scenarios plot variations in water consumption, fluoride levels in water, and toothpaste use. In most scenarios, fluoride in drinking water dominates the total. The totals calculated indicate that the upper tolerable intake limit for adults and children over 15 (7 mg/day) is only exceeded in areas with high natural levels of natural fluoride in water, and where people drink 2,800 ml of water a day. If they use normal amounts of toothpaste, they are taking in 8.85 mg/day of fluoride, and the figure rises to 9.00 mg/day if their toothpaste use is high.
The scenarios suggest that the tolerable limit is not exceeded in areas with artificially fluoridated drinking water, which has a good deal less fluoride than is found in the regions with the highest naturally occurring levels.
The situation for children is rather different. The assessment covered three age groups – 12-15 years, 6-12 years and 1-6 years, and had to make more assumptions because of lack of data. In the SCHER scenarios, it was difficult for children 12-15 years old to exceed their maximum tolerable intake of fluoride unless they drank 1.5 litres of water containing 3.0 mg/L and used more than the recommended amount of a high fluoride toothpaste. A few might also exceed the dose by using fluoridated salt on their meals or drinking high fluoride mineral water.
For the under 12s, the risks were greater. For 6-12 year-olds, the SCHER used a tolerable intake of 2.5 mg/day, based on a figure estimated to give a prevalence of below 5 per cent of moderate fluorosis in 4-8 year-olds. This could be exceeded if they drank 1.5 litres of water containing 1.5 mg/L of fluoride, no matter how careful they were about swallowing toothpaste.
Still younger children, 1-6 years old, swallow more toothpaste, and can exceed a maximum tolerable dose set at 1.5 mg/day of fluoride at fluoride levels in drinking water as low as 0.8 mg/L. If they drink enough, they may even exceed this level without using toothpaste at all.