Health risk assessment of food borne mycotoxigenic fungi and mycotoxins in staple foods in rural northern Namibia

Cooperating countries: Namibia and Austria

Coordinating institution: University of Namibia (Namibia), Prof. Jane Misihairabgwi, jmisihairabgwi@unam.na

Partner institution: University of Natural Resources and Life Sciences, Vienna (Austria)

Project duration: 1 June 2021 - 31 May 2023

Budget: EUR 19.250

Abstract:

Cereal grains and legumes are important staple foods in rural subsistence farming households in Namibia. Owing to subtropical climatic conditions favoring fungal growth, and lack of necessary agricultural expertise regarding pre- and postharvest crop management, fungal infestation of these staple foods and subsequent mycotoxin contamination is a prominent food safety challenge in these communities. Traditional and conventional practices for food processing and storage do not guarantee protection against fungal infestation, resulting in food losses, and consumption of mycotoxin contaminated food. Food and nutrition security is threatened, while chronic consumption of mycotoxin contaminated food poses human health risks. Human exposure to mycotoxins, which are secondary fungal metabolites, may result in acute mycotoxicosis or chronic exposure effects like esophageal and liver cancer, immune system suppression, adverse effects on female reproduction and growth impairment in children. Monitoring of mycotoxin exposure and assessment of health risks in low socio-economic rural communities where dietary diversity is limited and frequency of consumption of mycotoxin prone foods is high, is necessary. The project is mainly aimed at assessing the magnitude of mycotoxigenic fungal infestation of staple foods, mycotoxin contamination and associated health risks. Specifically, the project will focus on surveillance field studies, mycological and liquid chromatography-tandem mass spectroscopy analysis to determine the magnitude of contamination of mycotoxigenic fungi and mycotoxins in the staple foods, and development of community specific viable and sustainable postharvest mycotoxin reduction strategies. The magnitude of human exposure to multiple mycotoxins will be determined using urinary biomarkers and probable daily intake deterministic methods.

Summary: 

Cereal grains and legumes serve as staple foods for many rural subsistence farming households in Namibia. However, due to the country's subtropical climate, which fosters fungal growth, and the limited agricultural expertise in pre- and postharvest management, fungal infestation and mycotoxin contamination pose significant food safety challenges. Traditional food processing and storage practices have proven inadequate in preventing fungal growth, leading to food losses and increased consumption of contaminated food. This, in turn, threatens food and nutrition security while exposing communities to severe health risks.

This project was conducted to assess the extent of mycotoxigenic fungal infestation in staple foods, evaluate mycotoxin contamination levels, and determine associated health risks in affected communities. Surveillance field studies were carried out in selected rural regions, where household food samples were collected for analysis. Mycological studies and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to quantify the presence and levels of mycotoxins in staple foods such as maize, millet, sorghum, and legumes. The findings revealed widespread fungal contamination, with several mycotoxins exceeding safe regulatory limits.

To assess human exposure, urinary biomarker analysis was conducted, along with a deterministic estimation of probable daily intake. Results indicated that individuals in these communities were exposed to multiple mycotoxins at levels that could pose long-term health risks. Chronic exposure was linked to potential adverse effects, including immune suppression, liver damage, esophageal cancer, reproductive health complications, and growth impairment in children. Recognizing the urgent need for intervention, the project also explored postharvest strategies tailored to local communities. Community-specific, sustainable approaches were proposed to mitigate mycotoxin contamination, focusing on improved drying techniques, proper storage conditions, and affordable biological or chemical detoxification methods. Capacity-building initiatives were also recommended to enhance awareness and empower farmers with knowledge on effective food safety practices.

The study underscored the importance of continued monitoring and intervention in mycotoxinprone regions. It provided valuable insights into food safety challenges faced by rural households and emphasized the need for policy-driven solutions to mitigate mycotoxin exposure and safeguard public health.