Risk assessment of aflatoxin in Iowa corn post-harvest using an event tree analysis: A case study

Mycotoxins are secondary metabolites produced by fungi found in corn and are anticipated to increase globally due to enhanced weather extremes and climate change. Aflatoxin (AFL) is of concern due to its harmful effects on human and animal health. AFL can move through complex grain supply chains in the United States, including multiple stakeholders from farms, grain elevators, grain and ethanol processors, and feed mills, before reaching end users, putting numerous entities at risk. Since corn is an essential food and feed product, risk management of AFL must be considered. This case study aimed to (1) calculate the probabilities of pivotal events with AFL in corn at Food Safety Modernization Act-regulated entities using an event tree analysis (ETA) and (2) propose recommendations based on factors identified through the ETA for AFL risk management. The ETA was based on historical AFL prevalence data in Iowa above a 20-part per billion (ppb) threshold (2.30%). Results showed four single-point failures in feed safety systems, where countermeasures did not function as designed. Failure is defined as the type 2 error of corn being infected with AFL <20 ppb, when it is >20 ppb, and the overall system fails to detect this with contaminated corn reaching end users. The success rate is defined as detecting the corn samples correctly >20 ppb. The average success rate was 50.14%, and the failure rate was 49.86%. It was concluded that risk-informed decisions are a critical component of effective AFL monitoring in corn, with timely intervention strategies needed to minimize the overall effects on end users.