Determining future aflatoxin contamination risk scenarios for corn in Southern Georgia, USA using spatio-temporal modelling and future climate simulations

Ruth Kerry,Brian Scully,Brenda V. Ortiz,Naresh Magan,Ben Ingram,Esther Garcia-Cela

doi:10.1038/s41598-021-92557-6

Abstract

Aflatoxins (AFs) are produced by fungi in crops and can cause liver cancer. Permitted levels are legislated and batches of grain are rejected based on average concentrations. Corn grown in Southern Georgia (GA), USA, which experiences drought during the mid-silk growth period in June, is particularly susceptible to infection by Aspergillus section Flavi species which produce AFs. Previous studies showed strong association between AFs and June weather. Risk factors were developed: June maximum temperatures > 33 °C and June rainfall < 50 mm, the 30-year normals for the region. Future climate data were estimated for each year (2000–2100) and county in southern GA using the RCP 4.5 and RCP 8.5 emissions scenarios. The number of counties with June maximum temperatures > 33 °C and rainfall < 50 mm increased and then plateaued for both emissions scenarios. The percentage of years thresholds were exceeded was greater for RCP 8.5 than RCP 4.5. The spatial distribution of high-risk counties changed over time. Results suggest corn growth distribution should be changed or adaptation strategies employed like planting resistant varieties, irrigating and planting earlier. There were significantly more counties exceeding thresholds in 2010–2040 compared to 2000–2030 suggesting that adaptation strategies should be employed as soon as possible.

Highlights

Climate change threatens future food security due to the probable increase in temperature and changes in precipitation patterns which could affect the distribution of where different crops may be viably g rown[1,2]
The United States Food and Drug Administration (FDA) has a limit of 20 ppb total AFs in corn, peanuts, cottonseed and other feed/feed ingredients intended for animal consumption, for immature animals
Several studies of ripening corn and stored corn have investigated the impact of climate-related abiotic factors on AFs or aflatoxin B1 (AFB1) contamination[8,22,23,24]

Summary

Introduction

Climate change threatens future food security due to the probable increase in temperature and changes in precipitation patterns which could affect the distribution of where different crops may be viably g rown[1,2]. Salvacion et al.[27] evaluated the influence of weather variables in different growth stages based on exceedance of the FDA 20 ppb threshold and it was found that drought conditions in the month of June were by far the most significant Based on this finding, Kerry et al.[15] used thresholds in June maximum temperatures (TMax) and June rainfall (RF) above and below climate normals, respectively to identify years and counties with different levels of contamination risk. Kerry et al.[15] used thresholds in June maximum temperatures (TMax) and June rainfall (RF) above and below climate normals, respectively to identify years and counties with different levels of contamination risk Their approach was validated by comparing the AFs concentrations for the different risk zones which were found to be significantly different and reflected the order of risk identified. In another study, weather variables were shown to explain 50-76% of the variation in AFs c oncentrations[28]

Objectives

Methods

Results

Conclusion