Evaluation of trace metal element contamination in kaolin and health risks associated with geophagy: A case study of Kimbanseke Commune, Democratic Republic of the Congo

Introduction In Kinshasa, kaolin consumption is a deeply rooted cultural practice, particularly among women. However, it represents a major exposure pathway for chemical contaminants, while the toxicological risks associated with trace metal elements (TMEs) remain poorly documented. Purpose This study evaluated health hazards associated with kaolin consumption. The overall objective was to assess health exposure risks among women in Kimbanseke to TMEs (lead, cadmium, and arsenic) resulting from geophagy. Specifically, the study aimed to (a) identify consumers and assess their level of exposure; (b) measure total concentrations of Pb, Cd, and As; (c) determine their in vitro bioaccessible fractions (gastric and intestinal phases) to calculate the Average Daily Dose (ADD), Hazard Quotient (HQ), and Hazard Index (HI); and (d) propose a decision-making tool. Methods A cross-sectional survey was conducted among 100 respondents in Kimbanseke. Physicochemical characterization was performed using X-ray fluorescence (XRF) to determine total metal concentrations. In vitro digestion simulation was conducted using a bioaccessibility model mimicking the gastric phase (pH 1.5) and intestinal phase (pH 7.0). Results XRF analyses revealed alarming total concentrations at Site 1 (Pb: 32.7 mg/kg; Cd: 11.1 mg/kg; As: 4.1 mg/kg) and Site 2 (Pb: 22.0 mg/kg; Cd: 1.8 mg/kg). These concentrations exceeded permissible limits set by WHO/FAO, notably the 2.0 mg/kg safety threshold for lead (Food and Agriculture Organization of the United Nations & World Health Organization, 2011) and 0.1 mg/kg for cadmium and arsenic. Bioaccessibility tests showed substantial release in the intestinal digestate (Pb: 0.90 mg/L; Cd: 0.16 mg/L; As: 0.13 mg/L). Risk assessment based on a daily consumption of 115 g over 15 years indicated potential health concern. However, inconsistencies were identified between reported bioaccessibility values and hazard indices, requiring recalculation for final risk classification. Conclusion Kaolin consumed in Kimbanseke contains TMEs above international guideline limits. The intestinal solubilization of metals indicates potential absorption and systemic toxicity. Public health intervention is required to regulate kaolin exploitation and raise awareness among consumers.