Since publication of the first EHC document on fluoride (WHO, 1984), additional information on the levels of fluoride in foodstuffs has become available. Virtually all foodstuffs contain at least trace amounts of fluoride. A summary of various studies in which the levels of fluoride in foods have been assessed is presented in Table 6.
Table 6. Levels of fluoride in foodstuffs
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Food Fluoride concentration (mg/kg)a Comment References
Milk and milk products
0.01-0.8 Range of concentrations in 12 varieties of dairy products in Canada Dabeka &McKenzie (1995)
0.045-0.51 Range of mean concentrations in 13 varieties of dairy products in Hungary Schamschula et al. (1988a)
0.019-0.16 Range of concentrations in milk and milk products sampled between 1981 and 1989 in Germany Bergmann (1995)
Meat and poultry 0.04-1.2 Dabeka & McKenzie (1995)
Range of concentrations in 17 varieties of (cooked and raw) meat and poultry in Canada
0.01-1.7 Range of mean concentrations in 7 varieties of meat and poultry in Hungary Schamschula et al. (1988a)
0.29 Mean concentration in canned meat and sausage sampled between 1981 and 1989 in Germany Bergmann (1995)
Fish 0.21-4.57 Dabeka & McKenzie (1995)
Range of concentrations in 4 varieties of fish available in Canada
0.06-1.7 Range of concentrations in 6 varieties of fish available in the USA Whitford (1996)
Soups 0.41-0.84 Range of concentrations in 4 varieties of soup available in Canada Dabeka & McKenzie (1995)
0.42-0.94 Range of mean concentrations in 7 varieties of soup available in Hungary Schamschula et al. (1988a)
Baked goods and Cereals
0.04-1.02 Range of concentrations in 24 varieties of baked goods and cereals available in Canada Dabeka & McKenzie (1995)
1.27-1.85 Range of mean concentrations in rice consumed in three villages in China Chen et al. (1996)
0.06-0.49 Range of mean concentrations in 13 varieties of baked goods and cereals available in Hungary Schamschula et al. (1988a)
0.05-0.39 Range of concentrations in bread and grains sampled between 1981 and 1989 in Germany Bergmann (1995)
Vegetables 0.01- 0.68 Range of concentrations in 38 varieties of raw, cooked and canned vegetables in Canada Dabeka & McKenzie (1995)
0.28-1.34 Range of mean concentrations in three staple vegetables consumed in three villages in China Chen et al. (1996)
0.01-0.86 Range of mean concentrations in 24 varieties of vegetables available in Hungary Schamschula et al. (1988a)
0.023 Mean concentration in some vegetables sampled between 1981 and 1989 in Germany Bergmann (1995)
0.01-0.58 Range of concentrations in 25 varieties of fruit and fruit juices available in Canada Dabeka & McKenzie (1995)
Fruits and fruit juices
0.03-0.19 Range of mean concentrations in 16 varieties of fruits and fruit juices available in Hungary Schamschula et al. (1988a)
0.02-2.8 Range of concentrations in 532 varieties of fruit juice and juice-flavoured beverages in the USA Kiritsy et al. (1996)
Mean concentration in some fruits sampled between 1981 and 1989 in Germany
0.027 Bergmann (1995)
0.014-0.35 Range of concentrations in some fruit juices sampled between 1984 and 1989 in Germany Bergmann (1995)
Fats and oils 0.05-0.13 Range of concentrations in 3 varieties of fats and oils available in Canada Dabeka & McKenzie (1995)
Sugars and candies 0.01-0.28 Range of concentrations in 7 varieties of sugar-containing products available in Canada Dabeka &  McKenzie (1995)
Range of mean concentrations in 12 varieties of sugar-containing foods available in Hungary
0.01-0.31 Schamschula et al. (1988a)
Beverages 0.21-0.96 Range of concentrations in 6 varieties of beer, wines, coffee and soft drinks available in Canada Dabeka & McKenzie (1995)
0.19-0.78 Range of mean concentrations in 3 varieties of coffee and soft drinks available in Hungary Schamschula et al. (1988a)
0.003-0.39 Range of concentrations in some soft drinks sampled between 1984 and 1989 in Germany Bergmann (1995)
0.02-1.28 Range of concentrations in 332 samples of soft drinks sold in Iowa, USA, between 1995 and 1997
Heilman et al. (1999)
Tea 4.97 Concentration in tea available in Canada Dabeka &  McKenzie (1995)
90.94-287.9 Range of mean concentrations of tea consumed in 3 villages in China Chen et al. (1996)
243.7 Mean concentration in 4 samples of tea leaves used in Hungary Schamschula et al. (1988a)
82-371 Range of concentrations in samples of 32 tea leaves purchased in Hong Kong Wei et al. (1989)
0.005-0.174 Range of concentrations in herbal and children's teas sampled between 1984 and 1989 in Germany Bergmann (1995)
0.37-2.07 Range of concentrations in black tea sampled between 1984 and 1989 in Germany Bergmann (1995)
a For liquid items, concentrations are in mg/litre.
Tea leaves are particularly rich in fluoride (see Table 6). The concentration of fluoride in brewed tea is dependent upon the concentration of soluble fluoride in the tea leaves, the level of fluoride in the water used in its preparation and the length of the brewing period (Smid & Kruger, 1985). Chan & Koh (1996) reported that the mean concentration of fluoride in 21 brands of caffeinated tea, 11 brands of decaffeinated tea and 12 brands of herbal tea purchased in the USA and brewed (with water containing <0.02 mg fluoride/litre) for 5-120 min was approximately 1.5?2.4, 3.2?4.2 and 0.05?0.1 mg/litre, respectively. The levels of fluoride in 40 brands of brewed and instant coffee purchased in the USA ranged from 0.1 to 0.58 mg/litre, with no significant difference between caffeinated and decaffeinated coffees (Warren et al., 1996).
The concentration of fluoride in food products is usually not significantly increased by the addition of superphosphate fertilizers to agricultural soil (Oelschläger, 1971), due to the generally low transfer coefficient from soil to plant material. However, a recent study by McLaughlin et al. (2001) found significant increases in fluoride concentrations in herbage harvested from plots fertilized with phosphate fertilizers (537 kg total phosphorus added over 59 years) over a long period (22 mg fluoride/kg) compared with concentrations in herbage harvested from unfertilized plots (11 mg fluoride/kg). These data suggest that, given the right soil conditions and application of sufficient fluoride as an impurity in phosphate fertilizers to soils, plant uptake of fluoride can be increased. The use of water containing relatively low (<3.1 mg/litre) levels of fluoride for crop irrigation generally does not increase foodstuff fluoride concentrations (Schamschula et al., 1988a). However, this is dependent on plant species and fluoride concentrations in soil and water. For example, Kabasakalis & Tsolaki (1994) showed that fluoride concentrations in vegetables irrigated with water containing 10 mg fluoride/litre were increased compared with fluoride concentrations in vegetables grown with irrigation water containing low fluoride concentrations (0.15 mg/litre). They also commented that fluoride has a tendency to accumulate in the vegetable leaves rather than in the fruits.
Levels of fluoride in foods are significantly affected by the fluoride content of the water used in preparation or processing, most notably in beverages and dry foodstuffs to which water is added prior to consumption (Kumpulainen & Koivistoinen, 1977; Schamschula et al., 1988a). In a study conducted in a rural area of China, immersion of vegetables in hot spring water containing elevated levels of fluoride (approximately 20.3 mg/litre) reportedly led to a significant increase in the fluoride content of the food product (Xu et al., 1995). The concentration of fluoride in water used to parboil rice influenced the level in the final product (Anasuya & Paranjape, 1996). The concentrations of fluoride in unwashed or unprocessed foods grown in the vicinity of industrial sources (emissions) of fluoride in Japan (Sakurai et al., 1983; Tsunoda & Tsunoda, 1986; Muramoto et al., 1991) and the United Kingdom (Jones et al., 1971) have been up to 100-fold greater than the levels in the same foods grown in other non-industrially exposed areas.
In commercially available infant formulas sold in the USA, soy-based ready-to-use and liquid concentrate formulas contained higher levels of fluoride than the equivalent milk-based products; however, no significant difference was observed between soy- and milk-based powdered infant formulas (McKnight-Hanes et al., 1988) (Table 7). The mean concentrations of fluoride in liquid milk- and soy-based concentrated formulas diluted with water containing 1 mg fluoride/litre were 0.62 and 0.74 mg/litre, respectively. The mean concentrations in powdered milk- and soy-based formulas diluted with water containing 1 mg fluoride/litre were 0.83 and 0.85 mg/litre, respectively (McKnight-Hanes et al., 1988). For infant formulas available in Australia, the average concentrations of fluoride in powdered milk- and soy-based formulas diluted with water containing 1 mg fluoride/litre were 1.2 and 1.34 mg/litre, respectively (Silva & Reynolds, 1996). Studies of fluoride levels in infant foods available in Germany revealed mean concentrations generally of 0.02?0.3 mg/litre (Bergmann, 1995). In other studies (see Table 7), levels of fluoride in infant formulas have ranged from 100 to 1600 �g/litre (Fomon & Ekstrand, 1993). A study of a variety of infant food products available in the USA indicated concentrations of fluoride ranging from 0.01 to 8.38 �g/g; the highest concentrations were in products containing chicken (Heilman et al., 1997). In other infant food and beverage products (see Table 7), fluoride levels ranged from 10 to 6000 �g/litre (Fomon & Ekstrand, 1993). Reported levels of fluoride in breast milk have ranged from <2 to 100 �g/litre, with most values being between 5 and 10 �g/litre (Ekstrand, 1981; Esala et al., 1982; Dabeka et al., 1986; Bergmann, 1995).
Table 7. Concentrations of fluoride in infant foodsa
Food item Fluoride concentration (�g/litre)b Reference
Human milk 5-10 Esala et al. (1982); Spak et al. (1983); Ekstrand et al. (1984)
Cow's milk 30-60 J. Ekstrand (unpublished data)
Formula Johnson & Bawden (1987); McKnight-Hanes et al. (1988)
Ready to feed 100-300
Concentrated liquid
Milk-based 100-300
Isolated soybean-based 100-400
Powdered
Milk-based 400-1000
Isolated soybean-based 1000-1600
Most products other than dry cereals 100-300 Singer & Ophaug (1979); Dabeka et al. (1982)
Fruit juices Singer & Ophaug (1979); Dabeka et al. (1982)
Produced with non-fluoridated water 10-200
Produced with fluoridated water 100-1700
Dry cereals Singer & Ophaug (1979); Dabeka et al. (1982)
Produced with non-fluoridated water 90-200
Produced with fluoridated water 4000-6000
Wet-pack cereal fruit products 2000-3000 Singer & Ophaug (1979); Dabeka et al. (1982)
Poultry-containing products 100-5000 Singer & Ophaug (1979); Dabeka et al. (1982)
a From Fomon & Ekstrand (1993); Fomon et al. (2000).
b Concentration ranges have been rounded off. Most reported values fall within the ranges listed in the table.
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