The chief medical officer of the United Kingdom, Chris Witty, recently concluded that it would be good policy to add the chemical fluoride to local drinking water. In fact, the practice is employed in many nations to varying degrees, but it is not without its detractors. This is because fluoride toxicity causes fluorosis, a disease afflicting millions of people around the world.
What is fluorosis?
Fluorosis, or chronic intoxication with fluorine, can result in changes in the skeleton and ossification of tendons and ligaments. Exposure to fluoride in optimum amounts, however, is believed to be beneficial to the teeth in preventing decay. Most commonly, mild chronic exposure causes mottling of tooth enamel in children, with bones left unaffected. In more severe chronic exposure, bone calcium is replaced by fluorine, which leads to bones becoming soft and crumbly.
There are early warning signs of the condition, but over time symptoms include stiffness, inability to move the spine, and even neurologic issues due to compression of nerves.
Fluorosis is largely caused by consumption of water containing high levels of fluoride. The element occurs naturally in rocks and sediment, and from there it enters bordering water. Elevated inorganic fluoride is often seen in regions with geothermal or volcanic activity. Additionally, industrial activity can also contribute fluoride to the environment.
Fluorosis is a global concern endemic in at least 25 countries.
This is largely attributed to fluoride-rich rock belts; one of which stretches from Syria through Jordan, Egypt, Libya, Algeria, Morocco, Sudan, and Kenya. Another stretches from Turkey through Iraq, Iran, Afghanistan, India, northern Thailand, and China. There are similar belts in the Americas and Japan.
Regions of concern
Asia is the worse afflicted continent, with fluorosis being particularly widespread in China and India.
A general survey identified cases of fluorosis in more than 7100 Chinese villages, across 1000 counties. It is estimated that there are currently over 21 million patients with dental fluorosis and over 10 million patients with skeletal fluorosis in China. As well as the usual ingestion via naturally fluoridated drinking water, in China, inhalation from fluoridated coal smoke used in cooking is also a contributor.
As of 2014, fluoride prevalence was reported in 230 districts in 19 Indian states, with more than 14000 homes in the at risk areas still lacking safe drinking water. The population at risk is officially estimated to be around 11.7 million, while NGOs warn that the threat is more likely impacting 60 million people nationwide.
Endemic fluorosis in severe forms is exclusively found in areas of the world with high levels of natural fluoride in local water. The reason artificial fluoridation of drinking water is performed at all is that it has been linked to significant reductions in the population-wide prevalence of tooth decay.
At the optimal levels, fluoride in water is believed to protect the enamel of teeth from acids due to the way it interacts with phosphate and calcium. For the same reason, it is added to fluoride toothpaste.
However, the levels of fluoride needed to provide this health benefit are relatively low. Due to the way fluoride is present in groundwater at different concentrations depending on localised geology, a lot of drinking water contains the right amount of fluoride to protect teeth without upticks in indicators of fluorosis. As we have seen, in other areas there is far too much fluoride, and fluorosis has become a serious problem.
In many countries, fluoride levels in water are far lower. In such cases, health authorities sometimes choose to artificially add fluoride to water supplies in tiny amounts. Given the risks involved, this is a precise process requiring constant monitoring of water; one that, nonetheless, is a source of contention.
The majority of developed nations do not fluoridate their water. Globally, there are reportedly 24 countries with water fluoridation programs.
Of these, there are 11 countries where less than 20% of the population consumes artificially fluoridated water: Argentina, Guatemala, Panama, Papa New Guinea, Peru, Serbia, Spain, South Korea, the United Kingdom, and Vietnam.
There are 10 countries in the world where more than 50% of the population drink fluoridated water. They are Australia, Brunei, Chile, Guyana, the Irish Republic, Malaysia, New Zealand, the United States, and notably Hong Kong and Singapore, where 100% of the national population consumes artificially fluoridated water.
In total, roughly 5% of the world’s population drinks artificially fluoridated water.
In Western Europe, only 3% of the population consumes artificially fluoridated water. Various methods of fluoride delivery have been employed in the prevention of tooth decay for 70 years in Europe, including fluoride toothpaste, fluoridated salt, and water.
The debate on the safety of these practices continues, though science groups reporting to the European Union have assessed, and continue to assess, ongoing risk factors. They have concluded so far that risk of fluorosis in Europe appears very low. Where it does appear at all, it is almost exclusively the mild, purely aesthetic dental form that speckles teeth.