Health risk assessment to fluoride in groundwater of Moutourwa Health District in Northern Cameroon: a multi-pathway exposure analysis

Fluoride contamination in groundwater is a global health concern, particularly in areas where communities rely on untreated groundwater for drinking and domestic use. This study assessed fluoride concentrations in different groundwater sources and evaluated non-carcinogenic health risks through multiple pathways in Moutourwa Health District, Northern Cameroon. A total of 34 groundwater samples were collected from boreholes, wells and supply networks. Fluoride concentrations were measured using HACH DR/3900 spectrophotometer. Hazard Quotient and Hazard Index were used to assess health risks in infants, children, adolescents, and adults. Results showed that fluoride concentrations ranged from 3.18 to 4.75 mg/L, all samples largely exceeding WHO guidelines and local threshold. Hazard Index (HI) values ranged from 3.578 to 4.769, exceeding the safe threshold of 1 across all age groups. Infants (0–2 years) are the most vulnerable age group (HI: 4.769–4.958), followed by children (HI: 3.833–3.985), adolescents (HI: 3.579–3.721), and adults (HI: 3.578–3.720). Dermal exposure contributes less than 0.5% of total risk, confirming that ingestion is the dominant pathway. These findings would be useful in future monitoring of groundwater in Moutourwa Health District and in Northern Cameroon.