Human Consumption of Clays in Africa Poses High Health Risks from Dioxins and Requires Policy Action

Abstract

This study investigates human exposure to unintentionally produced persistent organic pollutants (POPs) through geophagy involving edible clays and soil in Africa. The concentration of PCDD/Fs, PCBs, PCNs, PeCB, HCB, and HCBD were determined in 18 edible clay and termite mound soil samples from Nigeria and Botswana using HRGC–HRMS, GC–MS/MS, and GC–MS. PCDD/Fs were detected in all samples. Only two edible clays from Ogun State (0.03–0.04 pg WHO2022-TEQ/g) were below the European regulatory limit for minerals in feed additives (0.75 pg TEQ/g), while other clays ranged from 10.8 to 75.7 pg WHO2022-TEQ/g. Termite mound soils showed 1.8–1.9 pg WHO2022-TEQ/g. Consumption of some clay even exceeded European health guidelines over 200-fold. Other POPs contributed minimally to overall toxicity. Edible clay consumption is an important exposure pathway for PCDD/Fs, posing considerable health risks, particularly to pregnant women and infants. Urgent systematic monitoring, source control, and risk-based regulation are warranted.