Fluorosis, caused by excess fluoride intake, affects millions of people around the world. As part of our City Health and Wellbeing (CHeW) initiative, we are working with local communities and Indian doctors to identify options to manage fluorosis risk in Nakuru, Kenya. In focus groups, we found that stakeholders in Nakuru identified excess fluoride in drinking water as an important concern. A combination of water supply management and community sampling is helping better understand the scale of the problem, and the solutions.

We are also collaborating with medical professionals from Ramaiah Medical College and Hospital in Bengaluru, India, who are experienced in diagnosing and reducing fluorosis risk. The transfer of knowledge from Ramaiah College to practitioners, health officials and communities will be a major step forward in addressing the issue in Nakuru.

Health impacts related to fluoride

Fluoride is often considered beneficial for dental health and for protection against caries, and in many countries fluoride is added to municipal drinking water supplies as a cost-effective public health policy. According to WHO standards, a guideline level of fluoride in drinking water is 1.5 milligrams per litre (WHO 2017). Long-term exposure to high levels of fluoride – i.e. above 6 milligrams per day – can lead to harmful health effects such as dental caries and skeletal fluorosis. Teeth can become brittle, leading to superficial porosity (Gevera et al., 2018) and teeth can become stained and pitted (see photo).

In skeletal fluorosis, fluoride accumulates progressively in the bone over many years. Early symptoms include stiffness and pain in the joints. Severe skeletal fluorosis is associated with osteosclerosis, calcification of tendons and ligaments, and bone deformities.

The doctors at Ramaiah Medical Centre were concerned about the poor state of school children’s teeth in the local village of Kaiwara, as well as high numbers of children with genu valgum, commonly known as “knock-knee” as shown in the photo below.

Doctors initially assumed that poor dental hygiene and consumption of betel leaf were contributing to the children’s tooth decay, but found instead that they actually cleaned their teeth twice a day and did not chew betel. People can be exposed to raised levels of fluoride from multiple sources, for example drinking water, beverages, food grown in fluoride-rich water, toothpaste, and mouthwash. Based on testing of the drinking water, and urine sampling, the doctor’s conclusion was that water-borne fluorosis was endemic in Kaiwara, and was the probable cause.

What did the Ramaiah doctors do?

The doctors set about raising awareness of the problem. Firstly, they spoke with school children in the village about the causes and prevention of fluorosis, including providing dietary advice. Following this, they met with the Kaiwara Grama Pamchayath (the head community leader pictured in the photo below) and then with other local leaders, women’s groups (see photo) and youth groups. Because there is no alternative source of water with acceptable fluoride levels in the village, the doctors proposed to the villagers the solution of using reverse osmosis (RO) technology to de-fluoridate the water supply.

The overwhelming majority of heads of family – 89.8% – accepted that de-fluoridation of water in the village was necessary, and of these 99.4% were willing to pay for processed water.

The Gram Panchayath granted a plot of government land to build the infrastructure required to install the 40 000 litre RO plant provided by India’s Council of Scientific and Industrial Research. The five-rupee per month charge for the processed water paid by the villagers covered:

• electricity and water charges for running the RO plant
• maintenance charges for the RO plant
• salaries for the watchman, water distributor, plant operator and electrician
• maintenance and petrol for running the transport vehicle.

Outcomes and ways forward

The project faced a number of challenges, including irregular electricity supply, and maintenance of the RO unit. Despite these challenges, further urine sampling after the treatment plant was completed confirmed that this intervention in lowering fluoride levels below WHO limits, had been successful.

SEI is now taking the approach learned in India to Nakuru, the fourth biggest city in Kenya, with a population of around 500 000. It is located on the Central Rift Valley, an area which has one of the world’s highest levels of fluoride in groundwater.

The Nakuru Water and Sanitation Services Company (NAWASSCO), supplies surface water to a fraction of the population, with the rest using groundwater from approximately 24 boreholes across the city. While there is a lack of data on fluoride levels for the city specifically, water samples taken all over Nakuru county record levels between 0.5 and 72 milligrams per litre (a mean of 11.08 mg/L). It is not unsurprising then to find high levels of fluorosis in the area. A small study of two healthcare facilities found that in a sample of 173 patients, 83% had the disease. Higher rates were found in the younger population group compared with the older population group, which tallies with the study in Kaiwara (Isaac et al., 2010, Arvind 2012).

Next steps

The CHeW initiative has already conducted a literature review that covered fluoride occurrence in water, the benefits and risks of fluoride exposure, risk assessment methods, and research on water supply and fluoride specifically in Nakuru. The next stage of the study is to involve communities and stakeholders in further citizen science approaches to co-identify pathways of fluoride exposure, conduct water analysis, and engage with other stakeholders (municipal authorities, water providers, other utility companies, researchers and NGOs) to develop measures to tackle the problem. We also propose a more detailed epidemiological assessment of the extent of fluorosis in Nakuru involving 1500 citizens. Furthermore, groundwater sampling and mapping of utility supplies and access points, including boreholes, can help determine where and to what extent local people are exposed to high levels of fluoride.

The optimum solutions for reducing the burden of risk to Nakuru’s population will likely combine water supply alternatives (e.g. switching from groundwater to surface water) and de-fluoridation of groundwater. But for solutions to be implemented successfully, local people and stakeholders must be involved in the process.