Dr. Mary Tere Salas
Coordinator of the Investigation Area of the Salt Fluoridation Program of Costa Rica
Costa Rica has confirmed the success of the salt fluoridation program as a preventive measure with high coverage, control and low cost for the reduction of caries. Counting on the initiative of a group of dentists, under the direction and coordination of Dr. Ricardo González, together with the Ministry of Health and with support from the W. K. Kellogg Foundation, the Salt Fluoridation Program of Costa Rica started in 1987, making it the first country in America and the third in the world - after Switzerland and France - to apply this measure on a national level. The previous experience of water supply fluoridation in the whole urban area, which was applied from 1975 to 1980, didn't achieve the results expected, due to technical, economic and operational problems.
The main barrier to the fluoridation of public water supply in Costa Rica comes from the supply system itself: many national systems of aqueducts, managed by different entities. Furthermore, many rural communities still use well-water. As a result, control and dosage of the fluoride in the water supply in the various systems of aqueducts would end up representing a great economic expense way over the country's possibilities, which would make the whole program unfeasible.
In 1992, less than three years after the official start-up of the plan, it was possible to observe a reduction in the prevalence of caries in 48% of the children who used the fluoridated salt.
To get to know the habits of society and to establish application strategies: the first steps to turn fluoride into an indispensable ingredient in Costa Rica
At the beginning, in 1984, the first concern was to evaluate the oral health status of the population. It was verified caries prevalence in 7 to 13 year-old children, who showed a DMF too high for this age group - DMF was 9.13 and 11.30 to 12 to 13 year-old children respectively. In the same year, an analysis on salt consumption concluded that Costa Ricans had an average of 10g of salt per person per day.
In 1985 diagnostic researches kept on observing the average fluoride concentration in schoolchildren urine and in the water. Results confirmed the presence of 0.34mgF/l in school children and water carried a concentration of 0.2mgF/l. These results were consistent to set up a salt fluoridation program.
Some regions such as Cantones de Tierra Blanca and Llan Grande de la Provincia de Cartago showed higher levels of fluoride in the water, what made researchers choose for the sale of regular salt in these areas, supported by a specific campaign on the non-consumption of fluoridated salt.
The experience of other countries in this kind of measure, in Switzerland for instance, was not feasible at first for Costa Rica. In other countries, salt is totally refined, while most part of the salt in Costa Rica can be considered raw, with still 3% of humidity. Besides, the salt used by the population contained high degrees of impurities, such as dust, plants residues and even bacteria. Only after 1985, due to the project's set up, did the process of quality control start.
Only three companies were selected to take part in the national program - Coonaprosal (National Cooperative of Salt Products), Cooprosal (National Cooperative of Salt Producers), and Sal Diamante SA. Once tests of quality control and iodine addition were concluded, it was started the process of adding a solution of potassium fluoride directly to the dry salt. The mixture was carried out in a kind of mixer with individual blades, which was imported from the Netherlands. This first process led to an increase of humidity in the product that was not consistent with the rules specs (2% of humidity). Considering this, the alternative was to mix dry potassium fluoride, instead of the solution. Although the fluoride had to be ground to avoid salt hardening, the alternative was successful when mixing time was established to 20 minutes.
With this stage completed, the Costa Rican Institute of Investigation and Education on Nutrition and Health - INCINSA, the Pan-American Health Organization and the W. K. Kellogg Foundation, all coordinated with the Ministry of Health, decided to set up salt fluoridation definitely. The lack of rules or decrees that regulated the salt program concentrated all the success of the project in the hands of the participating organizations. Salt companies had a special role in this process of improving Costa Ricans oral health status, by taking upon all the additional costs in the set up of labs, in the hiring of personnel and in the improvement in the process and quality of salt production.
Only in 1989 were quality standards defined, specially physic-chemical characteristics, besides the addition of some 250mgF/Kg of salt. The determination of this dose was based on national studies on fluoride concentration in urine and water, on salt consumption per person and on other countries experience.
It was also decided to use sodium fluoride, which costs less than potassium fluoride, in a previous mixture with iodine. The result was a surprising improvement in the mixture process and in the dosage of fluoride within the limits established by the salt companies. In 1991, after all these good results, three more companies joined the program to manufacture mixers with national technology - one less barrier to the establishment of fluoridation programs not only in Costa Rica but in other countries unable to import high cost equipment.
Six years after the project's start up, results in the society surpassed expectations.
In 1992, six years after the salt fluoridation project started, it was accomplished the first evaluating study on the impact of slat fluoridation on school children. The result showed a significant caries decrease, mainly in 3 year-old children, who had consumed fluoridated salt since the age of 1 year old.
Although educational and preventive measures can not be disdained - they have showed no changes in the last five years - we can safely assert that we owe to salt fluoridation all the encouraging results. These data show the success of salt fluoridation as a feasible public health program, which is already being applied not only in Costa Rica but also in Brazil, Mexico, Uruguay, Jamaica, Colombia, Peru and France.
The table shows the success of the program with 3 to 5 year-old children. There was a decrease in caries prevalence of 48% and 36% respectively.
The total of 5 year-old children free of caries in 1988 was 11.1%, increasing to 20.9% in 1992.
As to 12 year-old children, analysis showed a decrease of 34% between 1988 and 1992.
The objective of this study is not only to evaluate the reduction of caries prevalence but also to contribute with important information on the determination and accommodation of fluoride dosage in the salt and to encourage other Latin-American and Caribbean countries to start similar programs.
Data from this study will also be published in the next issue of the Revista Fluoruracion al Dia, which is the official organ of Costa Rica Fluoridation Program.
Work and Research Staff:
Dr. Ricardo González, Present Coordination
Dr. Francisco Bianchini, Technical Advisor
Jesús Gomez, Engineer, Coordinator of Dromatology
Dr. Gerardo Díaz, Coordinator of Microbiology
Dr. Jorge González, Coordinator of Informatics
Dr. Ivania Solórzano, Investigation
Clinica Dental, 100 MTS Notre Iglesia do Guadalupe
San José - Costa Rica