In the city of Moanda, where one of the world’s largest manganese (Mn) deposits is located, the soils are very rich in manganese, which promotes the transfer of Mn from the soil to the various organs of fruits and vegetables that are grown near the manganese plateaus. Cassava is widely cultivated and consumed daily by the population of this region of Gabon. These cassava leaves pose a moderate but not negligible risk to the people who consume them daily. This study was conducted to assess the health risks to the population of this region who regularly consume cassava leaves. Manganese (Mn) concentrations in cassava leaves were measured at four sites in Moanda (La Gare, Leyima, L’Alliance, and L’Oasis), which have relatively high levels in the soil. The results show high concentrations of manganese in cassava leaves, concentrations above regulatory limits with a maximum of 48200 µg.kg-1. The risk factor calculation indicates that these concentrations represent a moderate but not negligible risk factor for the health of the inhabitants of Moanda who regularly consume cassava leaves.