Ground Hidden Risk Affecting Millions
Chronic exposure to high levels of fluoride in groundwater poses a major public health risk, particularly in Africa and Asia. The World Health Organization (WHO) recommends a maximum concentration of 1.5 mg/L in drinking water, yet many communities across the globe unknowingly consume water that far exceeds this limit. A cutting-edge global study by researchers at the Swiss Federal Institute of Aquatic Science and Technology offers new insight into where this risk is most concentrated—and what can be done about it.
Global Fluoride Hazard Map The study, led by Joel Podgorski and Michael Berg, utilized machine learning and over 400,000 fluoride samples (10% of which exceeded the WHO guideline) to create a global fluoride hazard map. The analysis reveals major hotspots in:
Central Australia
Western North America
Eastern Brazil
Several regions across Africa and Asia
The interactive hazard map provides a vital tool for governments and organizations aiming to monitor water safety and target interventions.
Africa: A Key Region of Concern Africa stands out, with 14 of the top 20 countries at highest risk located on the continent. In 15% of Africa’s land area, there is more than a 50% chance that fluoride levels exceed the safe limit of 1.5 mg/L.
Top affected African countries include:
Kenya: 7.5 million at risk
Ethiopia: 9.6 million
DR Congo: 15 million
Tanzania: 6.9 million
Nigeria: 7.4 million
Why Fluoride Accumulates in Water Fluoride occurs naturally in rocks and soils, especially in regions with volcanic, geothermal, or igneous activity. High fluoride levels are often found in aquifers located in areas with:
High pH and alkalinity
Low calcium concentrations
Warm temperatures
Long groundwater residence times
Health Implications Fluoride is not an essential dietary nutrient. While low levels can prevent dental caries, excessive intake—especially >1.5 mg/L—can cause:
Dental fluorosis: discoloration and damage to teeth
Skeletal fluorosis: debilitating bone disease, particularly at >6 mg/day intake
Global Guidelines and Standards Although WHO’s guideline is 1.5 mg/L, countries often set their own standards based on regional exposure:
India: 1.0 mg/L
USA: 2.0 mg/L
Kenya: 1.5 mg/L
Population at Risk (Top 10 Countries) Estimated Population at Risk (Million)
1. India 49 (26–89)
2. China 22 (1–50)
3. DR Congo 15 (2–16)
4. Ethiopia 9.6 (4.0–13.8)
5. Pakistan 7.6 (2.3–14.5)
6. Kenya 7.5 (4.2–8.3)
7. Nigeria 7.4 (1–17)
8. Tanzania 6.9 (3.7–7.9)
9. Uganda 4.8 (0.9–8)
10. Yemen 4.3 (2.6–4.4)
What This Means for Tabasamu Mtoto’s Work These findings underline the urgent need for targeted fluoride mitigation strategies in school water systems especially in regions like Kenya. Our work in oral health education and water purification directly contributes to mitigating this silent crisis. Awareness, testing, and sustainable water treatment solutions must become core components of public health strategies in affected areas.
Authors
Joel Podgorski, Department of Water Resources and Drinking Water, Eawag
Michael Berg, Swiss Federal Institute of Aquatic Science and Technology
Stay tuned as we continue our on-ground interventions and spotlight fluoride risks in our upcoming school visits.