Multi-mycotoxin Contamination in Maize from Niger State, Nigeria: Occurrence, Dietary Exposure and Health Risk Assessment

This study investigated fungal contamination and the occurrence of multiple mycotoxins in maize consumed in Niger State, Nigeria, and evaluated the associated health risks. A total of 240 maize samples (white and yellow varieties) were collected from markets and storage facilities across four distinct microclimatic zones. Fungal isolation was carried out using dilution plating, while mycotoxins were quantified using a combination of HPLC (aflatoxins, deoxynivalenol, nivalenol, cyclopiazonic acid) and ELISA (fumonisins, ochratoxin A, zearalenone) methods. The predominant fungi were Aspergillus species, particularly A. flavus and A. parasiticus , followed by Fusarium and Penicillium . Aflatoxins were present in all maize samples, with concentrations ranging from 0.003 to 682.9 µg/kg. Fumonisins and OTA were also widespread, detected in over 70% of samples, with fumonisin levels frequently exceeding EU maximum limits. Other mycotoxins (CPA, DON, NIV, ZEN) occurred at lower frequencies. Co-contamination was common, with up to five toxins detected simultaneously. Dietary exposure modeling based on local maize consumption indicated that fumonisins posed the highest intake risk, exceeding tolerable daily intake (TDI) values, while MOE calculations for aflatoxins and OTA were consistently < 10,000, suggesting significant health concern. The estimated hepatocellular carcinoma (HCC) burden associated with maize consumption was substantial, particularly among populations with high hepatitis B virus prevalence. The widespread maize consumption and frequent mycotoxin contamination pose a major food safety threat with public and trade implications. These findings emphasize the need for improved control measures, including better storage practices and regular surveillance, to mitigate risks associated with maize in Nigeria.