FLUORINE AND ITS ION, FLUORIDE (FI), are not essential to human existence, but they are of considerable nutritional interest because a large amount of FI accumulates in bone and dental tissues. Adequate levels of FI intake are associated with resistance to dental caries. (1,2) The dietary intake of FI is ingested primarily in water that, in most countries, contains 0-10 ppm F1--which occurs either naturally or from artificial supplementation. (3)

The FI ion concentration of tap water in Cairo, Egypt, was reported previously as 0.3 ppm. (4) The World Health Organization (WHO) has emphasized that, in setting national standards for FI, the consideration of climatic conditions, volume of water intake, and FI intake from other sources is particularly important. (5,6) The WHO 1971 global guidelines recommend limiting FI in drinking water to 0.6-0.8 ppm in areas that have ambient temperatures of 26.3-32.6 [degrees]C, and to 0.9-1.7 ppm at 10-12 [degrees]C. (7) The temperature in Cairo city is approximately 20 [degrees]C during winter and 30-40 [degrees]C during summer. A program for FI supplementation requires updating a local environmental health criteria document and a monograph on fluoride. (8)

In previous studies of children, investigators have reported a substantial increase in the consumption of beverages and a reduction in average tap water consumption. The main component of most beverages is water; therefore, the studies found that the FI content of beverages closely parallels that of the water used in their processing. (9,10) For example, the FI content in Egyptian market fruit juice was 0.2-0.85 ppm, whereas the FI content in carbonated beverages was 0.07-0.68 ppm. (11) A relevant study on carbonated soft drinks in the United States revealed FI concentrations of 0.02-1.28 ppm. (12)

Another important source of FI ingestion is tea. Raw tea leaves can contain as much as 400 ppm of FI. Therefore, in areas where tea drinking is a common practice, it can be an important source of FI intake. (13) Meat, fish, and eggs contain measurable amounts of FI. (14) Cereals contain approximately 1-3 [micro]g/gm dry weight of FI and are a major source of FI in infants. (15) The FI content of cereal grains and vegetables varies depending on the amount of FI in the soil and water in which they are grown.

The FI intake of infants from milk is of special interest because it is the main source of nutrition during an infant's 1st yr of life. The FI content of breast milk is very low and is consistently less than 0.01 ppm. (16) Bovine milk also contains very low levels of FI--generally less than 0.05 ppm. (17) The FI levels of commercially prepared milk- and soy-based formulas available in most countries are reportedly higher than levels found in human or cow's milk. (18,19) These products may provide even higher FI concentrations when reconstituted with fluoridated tap water. Accordingly, in 1979, U.S. manufacturers of infant formula agreed to reduce and control the concentration of FI in products they produced. (10,20)

Fluoride has played a pivotal role in oral health promotion for about 50 yr. (21) Its cariostatic effect is currently considered to be exerted primarily after tooth eruption (i.e., decreasing the rate of enamel demineralization and enhancing remineralization of early carious lesions). (10,21-23) FI acts at both the local and systemic levels. Locally, it prevents the surface demineralization of enamel by strengthening the superficial layers and inhibiting local bacterial activity. Systemically, FI improves enamel resistance by forming fluorapatite with calcium, which is stronger than hydroxyapatite. (22,24) The source of calcium may be either the enamel itself, saliva, or plaque fluid. (25,26)

FI is now used globally for the prevention of caries--mainly through water fluoridation and FI supplements. The former caries-prevention method is typically community-based, whereas the latter relies on individual motivation. (27) Individual FI supplements may be topical (i.e., dentifrices, gels, and rinses) or systemic (i.e., drops, tablets, and lozenges). The systemic forms are designed for use by children and adults who do not have regular access to optimally fluoridated water. (28,29) The goal of an efficient community-based fluoridation program is the maintenance of a constant low level of FI in as many months as possible at as low a cost as possible. (27)

Although the predominant beneficial effect of FI occurs locally in the mouth, the adverse effect--dental fluorosis--occurs systemically. (30) Konig (31) stated that the new recommendations, which are based on topical rather than systemic FI application, are superior for preventive, toxicological, psychological, and didactic reasons. Fluorosis is associated closely with FI intake during the period of tooth development, especially during the first 3 yr of life. (30,32) Children less than 6 yr of age swallow much of the toothpaste that they use to brush their teeth. It is, therefore, recommended that tooth brushing be performed under parental supervision. (33) Not only does fluorosis cause discoloration, pitting, and staining of teeth, (34) but it may also lead to skeletal fluorosis, nephrotoxicity, gastrointestinal upset, cardiorespiratory depression, and central nervous system manifestations. (35,36)