are required to treat each million gallons of water at the 1 part per million fluoride level. To get 4 grams at 1 time would require, not 20 pounds per million gallons water, but 10 tons per million gallons water. No machine or human could make that error for the capacity of the machine would not be that great. As a matter of fact, in discussing toxicity, there are many instances that can be cited where a chemical may be lethal in large amounts and beneficial in small amounts. Iodine, for instance, is poisonous in large quantities. Most of you have seen the "poison" label on a bottle of iodine. Yet in small quantities it is absolutely essential for the maintenance of life. Chlorine, used to kill bacteria in most of our water supplies, when used in minute proportions, was used as a poison gas in the First World War. Even common table salt, if consumed in large quantities, may produce death. Sodium fluoride is another example of a chemical, toxic in large quantities, and beneficial in small, controlled doses. How fluorides work to produce this reduction in dental caries has still not been completely settled. When consumed in the water supply during formation of the teeth it probably changes a portion of the crystalline structure of the tooth from a hydroxylapatite to a fluorapatite. We know from minerology that the fluorapatite rocks are very hard and very resistant to acid erosion. We now believe that dental caries is caused by the action of oral bacteria on sugars and carbohydrates in the mouth. The sugars are converted to acid, and the acid, initiates the carious lesion. If we can build a tooth structure resistant to these acids, then it should be resistant to tooth decay. We believe that this might be one explanation for the action of fluorine. When consumed in communal water supplies over a great number of years, even in minute quantities of 1 part per million, there may be some topical or surface action. As an analogy, it is like building a house of stucco. If you want a green house you can either include the green paint or pigment in the plaster, or you can apply the green paint to the surface after the plaster has set. By either means, the result is a green house, although the green paint incorporated in the plaster will probably last longer.

SUMMARY

In summary, may I say that there is evidence to indicate that fluorides used in communal water supplies will reduce dental caries. The reduction once acquired should persist for life. There is absolutely no reliable evidence to indicate that 1 part per million of fluorine incorporated into the communal water supply will produce deleterious effects. It is recommended that any community that has a supervised communal water supply should fluoridate its water.

BETTER DENTAL HEALTH THROUGH WATER FLUORIDATION-A PROGRESS REPORT

(Zachary M. Stadt)

INTRODUCTION

The purpose of this first Public Health Institute, as noted by Dr. Dummett, is to bring together the most promising or currently best thinking in the several fields of public health, with special emphasis on their application to the health needs of people in the rural areas.

Water fluoridation, as a proved method for the mass partial prevention of dental decay, can be applied wherever there is a community water-distribution system. Today, Norwood, Wash., with a population of 150 people, is adding fluoride to its water supply for expected dental health benefits. In time, it should be possible to assure that all water supplies, private or communal, will have beneficial fluoride concentrations.

BROAD ENDORSEMENT

The evidence demonstrating dental health benefits derived from water-borne fluorides is so overwhelmingly abundant and constantly increasing, that the meas ure is now endorsed by important international, national, and local groups concerned with health. Those organizations and agencies include the Interassociation Committee which is composed of the American Dental Association, the American Medical Association, the American Hospital Association, the American Nurse's Association, the American Public Health Association and the American

Public Welfare Association. Other endorsers are the Federation Dentaire Internationale, the National Research Council, the United States Public Health Service, the State and Territorial Health Officers, the State and Territorial Dental Health Directors, the American Association of Public Health Dentists, the majority of State dental societies, many State health departments, an increasing number of State medical societies, and hundreds of county dental and medical groups, boards of health, local professional organizations, and lay organizations such as the Jaycees, Rotarians, Lions, and Kiwanis.

TROWTH AND DEVELOPMENT OF FLUORIDATION

Among those who have contributed to a better understanding of the fluorinedental caries relationship are the moderator of this symposium, Dr. J. F. Volker (1) and our essayist Dr. S. B. Finn (2). From their observations and those of others (3) and (4) the adaptation of observed phenomena to practical application was but one step. On August 19, 1942, Dr. W. L. Hutton, health officer, proposed to the Brantford, Ontario, Board of Health that water fluoridation should be established for dental health benefits. The Provincial authorities refused the request (5).

In 1945, four studies were started: (a) Grand Rapids-Muskegon in Michigan; (b) Southbury-Mansfield, Conn.; (c) Newburgh-Kingston, N. Y.; and (d) Brantford-Sarnia, Ontario, Canada. The number of people involved in the 4-study areas totaled around 240,000. From 1945 to 1950 growth was slow, increasing to some 44 places in 14 States. The big spurt in 1951 followed endorsement by the United States Public Health Service, based on findings derived from their Grand Rapids, Mich., study and the endorsement by the American Dental Association.

The following comparison illustrates the rapid increase in fluoridation during the last year (the figures are not absolute): (see table I).

THREE PERCENT OF 15,000 WATER SUPPLIES HAVE FLUORIDATION IN OPERATION OR APPROVED

In his report to the State and Territorial health officers, Knutson (6) noted that (a) 93 percent of all public water supplies are in communities of 10,000 population or less, (b) that of the 16,750 public water supplies in this country

If we correct the totals for population increases and those on the distribution systems who are not included in the community census, we could add 5 percent, hence the April 1951 total would be 23,432,264 and the March 1952 total would be 38,651,195.

some 15,000 do not contain natural fluorides, and (c) that at the present rate of development it would take 150 years to complete the job of getting all the water supplies fluoridated.

At the present time some 200 communities are fluoridating and around 250 others have registered their approval, for a total of 450 places or 3 percent of the 15,000 communities with fluoride-deficient water supplies. If all 450 places should be in operation in the near future, they would represent a total population of some 20,000,000 people, or one-fifth of the 100,000,000 people on community water distribution systems. How long will the remaining 14,550 communities with their 80 million population continue to deprive themselves of this assured method of mass partial prevention of dental decay? It is the job of all of us here to see that the job is done in the next 5 years, not the next 150. Of course, it is a big job, but it gets easier every day.

IMPORTANCE OF DENTAL EXAMINATIONS

Water fluoridation promotion represents an opportunity for dental health education in a dramatic and impressive manner. Today many communities have one or more responsible health workers who have some knowledge concerning the extent of the dental-health problem. Any or all of these health workers will be interested in bringing the dental-health problem into controllable limits.

Practically

General knowledge about the dental-health problem is not enough. everyone knows something about dental decay and diseases of the tissues which support the teeth, but how many hear or read specific dental-health facts for their own particular community? Because the answer to this question is very few, there should be made available reliable statistics on dental health. To obtain information about the extent of the dental-caries problem, dental examinations should be done on selected age groups. The proposed dental examinations can be done by the dentists or dental hygienists provided by the State department of health or by local dentists or dental hygienists employed by the local health department.

COOPERATION OF PARENT-TEACHER ASSOCIATION

When members of the Parent-Teacher Association act as recorders for the dental examiners it gives each parent first-hand information concerning the dental-health problem. Her observations are carried into the meetings of the Parent-Teacher Association with effectiveness. This can be the beginning of a drive to tell the people about the dental-health problem in the community. If there is no PTA, influential mothers should be drafted as recorders.

The dental examinations should be as extensive as possible, covering broad age groups. In all of these undertakings there is an important emphasis on the dental needs of children, but the long-range basic dental examinations should include representative groups at ages 20, 30, 40, 50, and 60.

The figures obtained from analysis of these examinations will provide a baseline against which future information can be compared. Of greater importance is the fact that it will be possible to tell the home folks the facts about the immediate dental-health problem in the community. When presented to the community in this way, dental-health statistics will begin to have the same significant impact on the people as information relating to VD, TB, cancer, cardiovascular-renal diseases, and infant and maternal mortality.

Standardized dental examination procedures can be arranged by the State dental director consulting with representatives of the State dental society, so that comparisons of dental findings from various communities will have a high degree of validity.

THE DENTAL PROBLEM AND EXPECTED BENEFITS FROM FLUORIDE

White children

Figure 1 combines Dean's graph (7) and (8) with Charlotte (N. C.) (9) data, all pertaining to children in the 12 to 14 age group. Using this information it is possible to demonstrate the fluorine-dental caries relationship in a practical way. Using Aurora as an example of what can be expected at around 1 to 1.20 parts of fluorine to a million parts of water, one can round off the figures and show that Charlotte white children (per 100) have 5 times as many teeth missing (60 to 11.4) almost 5 times as many teeth requiring extraction (17 to 3.5), twice as many teeth that have untreated caries (353 to 166.7), and more than 4 times as many teeth filled (418 to 99.4). For Charlotte white children age 12 and 14 there are 418 teeth filled and 60 extracted or a total of 478 teeth treated per 100 children. If the dental-caries experience at Charlotte for the 12- and 14 year-olds should be reduced to that observed at Aurora, then it should be possible to predict that after 14 to 15 years of fluoridation, with the same amount of services available, there will be few if any teeth with untreated dental caries and the few necessary extractions will have been fully taken care of, with a surplus of 197 services available for other age patients.

The data for Waukegan, Ill., and Charlotte, N. C., are particularly interesting because of the remarkable degree of similarity in findings and because the data represents the findings of Dean and his coworkers for Waukegan in the 1939-41 period, while the Charlotte data are derived from dental examinations by members of the Charlotte Dental Society and the speaker. Waukegan and

Charlotte will be cited in that order: Teeth extracted 69.5 and 60, extraction required 16.5 and 17, untreated decayed teeth 363.1 and 353, and teeth filled 361 and 418. Total dental-caries experience per 100 children: Waukegan, 810; Charlotte, 848.

Negro children

The importance of water fluoridation as a dental public health measure is brought into full relief when we examine the graphic analysis of the dental caries experience of Charlotte (N. C.) Negro children in the 12 and 14 age groups. The most striking figure is the number of teeth filled 29 per 100 children, or only 4 percent of the teeth attacked by decay; (Charlotte white children in the same age groups have almost 50 percent of their defective teeth filled.) Eighty-three percent of the teeth (605 per 100 children) have untreated dental decay.

REPORTS FROM STUDY AREAS

The data in the following tables give factual support to the benefits predicted from the fluoridation of community water supplies.

TABLE 2.-The effect of fluoridated water on the number of caries-free children

1 Control city: (a) Percent children with caries-free deciduous cuspids, 1st and 2d molars; (b) no def-DMF deciduous or permanent teeth; (c) no def deciduous teeth; (d) no DMF permanent teeth; (e) water supply contained 0.30 p. p. m. F prior to fluoridation.

If the Charlotte Negro children derive the same benefits from fluoridated water as observed for white children at Aurora, Ill., then 14 to 15 years after continuous fluoridation at Charlotte we may expect that caries experience for the 12- and 14-year-olds will be around 300 teeth per 100 children instead of the present 725, or a probable reduction of around 55 percent. Even if there is no increase in available services, the 29 teeth filled will represent corrections of around 10 percent of the defects, as contrasted with the present 4 percent. On the other hand, untreated dental caries will be reduced proportionately from 605 to around 231 teeth (allowing 40 teeth for extraction), or a reduction of 60 percent. Here then is the most striking expectation: a 60-percent reduction in the number of teeth with untreated dental decay, without any increase in the amount of available dental services.

NUMBER OF CARIES-FREE CHILDREN INCREASES

Table 2 shows how fluoridated water has influenced the number of children who have no dental decay. At Newburgh, N. Y., (10) after 60 months, there has been a 170-percent increase in the number of 5- and 6-year-old children who have no decay of the primary cuspids and first and second primary molars. At Brantford, Ontario, Canada, (11) after 77 months, there has been an increase of 208 percent in the number of children without decay of the primary and permanent teeth for the 5 to 16 age group. At Sheboygan, Wis., (12) and (13) after 65 months, kindergarten children without decay of the primary teeth increased 134 percent, while 12- to 14-year-old children without decay of the permanent teeth increased 23 percent.

The significant increase in the number of children with no caries experience of the primary and/or the permanent teeth in the early study areas should be considered as of a preliminary nature, with the expectation that greater benefits will be presented in subsequent reports.

PRIMARY (FOUNDATION) TEETH HAVE LESS DECAY

Table 3 represents a summary of some of the findings for the primary teeth. While there may not be unanimity in the method of estimating caries experience, it remains that where fluoridation has been in progress long enough the results show definite reductions in dental caries. For the 5-year-olds, for example, there were the following improvements: Grand Rapids (17) 38.9 percent less caries, Newburgh (18) 59.9 percent less, Brantford (11) 54 percent less, Sheboygan (12) 53.7 percent less for the 5- to 6-year-olds, and 48 percent less for the 5-year-olds at Madison (16). The increases noted at Charlotte (19) are due to our method of examination recording. Only the primary teeth present at the time of the examination are accounted for, hence it may be assumed that with fewer teeth lost because of extraction the number present at the time of the later examination is greater. The findings for the primary teeth of the 5-yearolds at Brantford after 77 months of fluoridation may very likely represent the maximum improvement.

FLUORIDATION BENEFITS PERMANENT TEETH

Reports on the reduction of caries experience for the permanent teeth have been collected in table 4. While the results are not in specific agreement, it is impressive that all reports indicate definite reductions, with the youngest age groups exhibiting the greatest benefits. Only the Brantford reports provide specific information for a group of 6-year-olds who had been consumers of fluoridated water since birth. Hence, most of the other reports are of a preliminary nature. It should be noted here, too, that preliminary definitive results will not be forthcoming until a group of 12- to 14-year-old children, who since birth have been continuous residents in one of the fluoride study areas, can be compared with a similar age group in a control city. To this we might add that an equally interesting comparison will be with the findings for the 12-14 age group in the study area during the prefluoridation period. Hence, the more extensive comparisons will not be available until around 1959-60. If the older age groups are to be included, and they should be, then more complete results will not be available until some time in the 1960-80 period. There are some who want to wait until that time before they give their approval, but in many instances they will have given it long before that-for fluoridation is no longer a mere proposal. These benefits noted here make fluoridation a fact.