Fluorides and Our Health

I

N

D

I

A

N

M

E

D

I

C

I

N

A

L

P

L

A

N

T

S

Fluorides were described as nutrients essential for human health, in the Federal Register of the U.S. Food and Drug Administration (see Tewari et al., 1990). Fluorides have repeatedly raised controversies regarding the desirability of supplementing fluoride intake through exogenous sources. There is an enormous commercial interest of the toothpaste manufacturers at stake and professional opinion is divided. Human populations obtain verying quantities of fluoride from drinking water, food and milk.

FLUORIDES IN WATER

Water with high fluoride content occurs at the foot hills of high mountain ranges and in areas with geological deposits of marine origin (Murray, 1986). Sea water has 800 to 1400 mg/L, while river water contains about 500mg/L. Water in several drier parts of India, as the Rayalaseema region of Andhra Pradesh, contain very high amounts of fluoride. In Tanzania some water samples contained 95,000 mg/L of fluorides.

FLUORIDES IN THE ATMOSPHERE

Fluoride content of the atmosphere originates from the soil-dust, gaseous industrial wastes, the burning of coal and gases from volcanic activity (Robinson and Eddington, 1946).

FLUORIDES IN PLANTS

Cereals and vegetables are often rich in fluorides as plants absorb fluorides. Higher levels of fluorides occur during the dry period. The concentration of fluorides in the leaves is usually low, less than one to 15 mg/g (Thomas and Alther, 1966), but higher concentrations occur in leaves exposed to polluted atmosphere 

(Jacobson et al., 1966). Barley and rice contain 2000 to 2100 mg/kg. When processed in fluoridated water, 4300 mg/kg accumulate in barley and 6400 mg/kg in rice.

The fluoride content of some common plants, used as food and in cleaning the teeth, was estimated by the very sensitive ion-selective electrode method, at the Atomic Minerals Division, Department of Atomic Energy, Bangalore (Shubharani, 1995; Appendix 38). The results show considerable quantities of water soluble fluorides in them and these are readily absorbed by the oral mucosa and the lining of the alimentary canal.

FLUORIDES IN MILK

Human milk contains low level of fluorides (30 mg/L) (Wilson et al., 1968). Fluoride content of dairy milk depends upon its levels in the cattle feed and water.

Mother’s milk offers protection against dental caries due to the presence of an anti-cariogenic factor, immuniglobulins and fluorides (Wilson et al., 1968).

RETENTION OF FLUORIDES IN THE TISSUES

Fluorides are readily absorbed by us but are easily excreted in urine, faeces, sweat and tears. Fluorides are retained in parts with high calcium deposition like the teeth and bones. In soft tissues, except the kidneys and thyroid, fluoride retention is generally low. Plasma fluoride levels are about 140 to 190mg/L.

FLUORIDES AND HUMAN HEALTH

a) Prevention of dental caries: children consuming water containing one mg/L of fluorides upto the age of 15 yr had a lower prevalance of dental caries;

b) Protection against osteoporosis: an appropriate level of dietary fluoride decreases the incidence of osteoporosis, defective bone maintenance resulting in porous, and so weak, bones, that occurs in elderly people, particularly post-menopausal women (Harper et al., 1977); and

c) Antibacterial activity: fluorides are very potential inhibitors of many bacterial enzymes and so derail their metabolism. 

Fluorides behave exactly like food in the body—beneficial in optimum doses and harmful when in excess. Excess fluoride, over above four mg/L in drinking water, can cause skeletal and/or dental fluorosis, renal damage and even mongolism (WHO, 1963). Fluoride levels higher than eight mg/L are considered to be carcinogenic. Several other symptoms are attributed to fluorides (WHO, 1970).

FLUORIDES AND DENTAL HEALTH

Fluorides have been found to prevent dental caries. But how fluorides act and what are the optimum levels, is not well settled. Moss (1992) considers that it requires a continuous daily exposure to fluorides to keep the teeth caries free. Fluorides get incorporated in the enamel crystal lattice and near the surface (Moss, 1992). Caries is caused by the acids produced by bacteria. Which species of the oral bacteria are cariogenic is not well understood. The action of the acids causes loss of minerals from the enamel (demineralisation) (Featherstone, 1987), which is inhibited when the fluoride ions are present in solution at the tooth surface. Enamel crystals formed in the presence of fluoride are larger and resistent to bacterial acidity (Moss, 1992). Frequent delivery of fluorides at the tooth surface enhances the healing of the early lesions of caries and inhibits demineralisation (Moss, 1992).

EXOGENOUS APPLICATION OF FLUORIDES

Exogenous supply of fluorides is in the form of fluoridated water, milk, salt, dentifrices, mouth rinses and topical application of sodium, phosphate or stannous fluoride and fluoride varnishes (Tewari et al., 1990).

Formation of enamel on our teeth stops by the age of 25 yr. About one mg/L of fluoride in water is generally agreed as the optimum level of fluoride required for the maximum beneficial effect in maintaining health (Strathdyde Research Council, Edinburgh, 1985). Under the best of circumstances caries prevention capability of fluorides is less than 80 per cent.

We do not require more than the maximum of two mg/L of fluorides, easily obtainable from drinking water, diet or herbal toothpowders. The fluoride content of exogenous sources is dangerously high. Many of the tooth pastes contain about 1000 mg/g and may be upto even 1,250 mg/g (Gauba et al., 1987). Unless a thorough medical examination indicates it, we do not need an exogenous application of fluorides. More so because, excess fluorides are detrimental to our health. Particularly, children below seven years and others over 25 years should be discouraged from an exogenous intake of fluorides, other than through drinking water and food.