Dr. Janna Schurer

Background: Dental fuorosis is caused by prolonged exposure to excessive fuoride during the period of permanent tooth formation and is characterized by tooth discoloration, pitting, and loss of shape. Communities living near Lake Kivu in Western Rwanda exhibit a high prevalence of dental fuorosis; however, data on prevalence and risk factors are scarce. Methods: This cross sectional, quantitative study used a One Health approach to investigate dental fuorosis preva lence among people and livestock and to measure fuoride content in the environment. In 2018, oral health examina tions were conducted to assess the prevalence of fuorosis in children (aged 9 to 15 years), cattle and goats residing on Gihaya Island (Rwanda, East Africa). All children and cattle/goats meeting basic eligibility criteria (e.g., island resi dence) were invited to participate. Presence and severity of dental fuorosis was categorized according to the Dean’s Fluorosis Index. Samples of local foods, water, soil and grass were collected from communal sources and individual households and analyzed for fuoride content using standard laboratory techniques. Descriptive and binomial analy ses (Fisher Exact Test) were used to assess this dataset. Results: Overall, 186 children and 85 livestock owners (providing data of 125 livestock -23 cattle and 102 goats) participated. Dental fuorosis was recorded in 90.7% of children and 76% of livestock. Moderate to severe fuorosis was observed in 77% children while goats and cattle most often exhibited mild or absent/questionable severity, respectively. Water from Lake Kivu (used primarily for human cooking water and livestock drinking water) contained fuoride levels that were consistently higher than the maximum threshold (1.5 mg/L) recommended by the World Health Organization. Other sources (borehole and rainwater) were within safe limits. All food, soil and grass samples contained fuoride. The highest levels were observed in porridge (0.5 mg/g) and small fshes (1.05 mg/g). Conclusions: Altogether, dental fuorosis was highly prevalent among children and goats on Gihaya Island with vari ous food and water sources contributing a cumulative exposure to fuoride. An immediate and coordinated response across human, animal and water professionals is needed to reduce fuoride exposure within safe limits for island residents