San José, Costa Rica, since 1956

Irazú Dental Woes Linked to Excess Flouride

Many people associate fluoride with toothpaste, mouthwash and dental hygiene. While public health officials have long cheered small levels of fluoride as an excellent way to fight cavities and prevent tooth decay, on the slopes of Irazú Volcano, in the eastern Central Valley province of Cartago, children are experiencing the consequences of too much fluoride, and they are not pretty.

Studies suggest naturally occurring fluoride in the drinking water of communities around the southern flank of Irazú Volcano has been causing dental problems for children in the area for years.

In 1995, almost 45% of children in this area had mild, moderate or severe dental fluorosis – an irreversible condition that strikes only children – according to a study performed by the Costa Rican Institute of Investigation and Education in Nutrition and Health (INCIENSA). Only 5-7% of the children are currently believed to have moderate or serious symptoms, however.

Dental fluorosis begins as almost imperceptible lines on teeth in its mild stages, can progress into white tooth stains that food will turn yellow or brown in its moderate stages, and in severe cases, the disease can fracture tooth enamel, explained Mary Tere Salas, an orthodontist and coordinator of the NationalOralHealthReferenceCenter at INCIENSA.

She described the condition as more damaging to appearances than health, and explained that consequently, it can affect children’s self-esteem.

Only children suffer ill effects from overexposure because excess fluoride affects the formation of enamel during the years when the permanent teeth are formed, from birth until approximately 8 years of age, according to Salas. After the tooth enamel is formed, fluoride can no longer damage it and is believed to in fact strengthen it against decay.

In the United States, where the use of fluoride appears to be more controversial than in Costa Rica, the American Dental Association (ADA) has promoted fluoridated drinking water for more than 50 years. This campaign, however, has been altered recently to exclude infants. According to the ADA Web site,, “fluoride intake above optimal amounts (for infants) creates a risk for enamel fluorosis in teeth during their development before they erupt through the gums.”

The U.S. Food and Drug Administration (FDA) last year allowed bottled water manufacturers to print on their labels that fluoridated water helps prevent tooth decay. The FDA, however, points out that the claim is not intended for water for infants.

Meanwhile, some environmental and public health groups in the United States are challenging the long-held belief that even small amounts of fluoride are beneficial, saying that ingesting fluoride runs a gambit of risks. The Environmental Working Group, a private U.S. environmental organization, cites a NationalAcademy of the Sciences report finding that fluoride could potentially affect the thyroid gland, and a Harvard study linking fluoridated water to an often fatal form of bone cancer.

While in the United States fluoride is commonly added to cities’ water supplies, in Costa Rica it is added to the salt.

In 1987, Costa Rica began adding fluoride to salt as recommended by the World Health Organization (WHO), turning the country into the first in the American continent and the third in the world to implement this cavity-reduction strategy, according to Salas.

Since the program began, tooth decay in 12-year-olds has dropped from an average of nine affected teeth per child to 2.5 teeth in 1999, the government orthodontist said.

When the fluoridated salt program was launched, communities experiencing fluorosis, namely those near the Irazú Volcano, were provided non-fluoridated salt. It is now the only type available in stores in those areas, Salas explained. Non-fluoridated salt is not available anywhere else in the country.

INCIENSA also began visiting local schools for meetings with parents and students to inform them about flourosis, as well as handing out flyers and building road signs advertising the use of non-fluoridated salt in the area.

Even without fluoridated salt, area residents continue to be afflicted by mostly mild manifestations of the disease.

INCIENSA’s OralHealthReferenceCenter has determined that the neighboring Cartago communities of Tierra Blanca, Llano Grande, Pacayas, San Rafael, Cot, Potrero Cerrado and Santa Rosa, all at the flanks of Irazú Volcano and where most of the country’s fluorosis cases are concentrated, have naturally occurring high levels of fluoride in their rivers and drinking water.

A study performed last year by a student from the University of Utrecht in The Netherlands, Gerke Floor, and the NationalUniversity’s Volcanological and Seismological Observatory of Costa Rica (OVSICORI), attempts to determine possible sources of fluoride contamination.

The study concludes that the high fluoride content in the area’s drinking water is likely connected to the nearby volcano.

“Volcanoes are like factories, they produce substances like arsenic,” said OVSICORI chemist María Martínez, who participated in the study.

According to Floor’s research, the fluoride levels in the area’s water sources could come from the interaction of volcanic gases with ground waters inside the active volcano or from volcanic rocks.

Moderate cases of fluorosis have also been noted throughout the country in the northwestern province of Guanacaste, the Northern Zone, the Caribbean and the Southern Zone, according to Salas.

Excess fluoride has not been found in the water in these areas, she explained, so for the time being most of these cases are considered to be the result of migration.

However, in Liberia, Guanacaste, INCIENSA plans to perform further studies into the cause of the severe fluorosis identified in two schools in the provincial capital.

Additionally, a new study examining fluoride concentrations in the urine of Irazú area children is slated for completion soon.


Comments are closed.