Insights into the Impact of Extreme Flood Events on Aflatoxin Contamination in Maize from Thessaly, Greece

Maize is highly vulnerable to aflatoxin contamination, constituting a serious food safety and public health concern. This study explored the relationship of extreme flood events in September 2020 (Storm Ianos) and September 2023 (Storm Daniel) in the Thessaly region, Greece, which occurred post-harvest, and aflatoxin contamination patterns in maize harvests of both the flood years and the following years (2021 and 2024). A total of 573 maize samples collected between 2019 and 2024 were analyzed using an enzyme-linked immunosorbent assay (ELISA). A 10 μg/kg cutoff was used (the ELISA upper limit of quantification); results > 10 ppb were classified as elevated concentrations. Overall, aflatoxins were detected in 47.8% of samples, with 14.0% having concentrations exceeding 10 μg/kg. The 2021 harvest year exhibited an exceedance rate of 28.75% (23/80), while the 2024 harvest showed a rate of 14.68%, 37/252. Exceedance rates during flood years were comparatively low; however, the maize harvested in the years following the flood events demonstrated a two-fold increase in the detection rate (60.2% vs. 30.7%) and a significant increase in exceedance percentages (18.07% vs. 8.30%) relative to non-flood years in the preceding period. While drought and heat remain the primary field risk factors for aflatoxin production, the correlational findings suggest that extreme floods may indirectly influence aflatoxin risk by increasing kernel damage, prolonging grain moisture, and disrupting post-harvest handling and storage, underscoring the need for continuous monitoring and robust mitigation strategies in flood-prone agricultural regions.