Assessing the Presence of Aflatoxins and Deoxynivalenol (DON)
To assess the effect of these conditions on aflatoxin and DON development, this report summarizes the results from official U.S. Department of Agriculture (USDA) Federal Grain Inspection Service (FGIS) aflatoxin tests and from independent DON tests for all the export samples collected as part of this survey. All (100%) of the samples (430) collected for this report were tested for aflatoxin and DON development.
A threshold established by USDA FGIS as the “Lower Conformance Level” (LCL) was used to determine whether or not a detectable level of the mycotoxin appeared in the sample. The LCLs for the FGIS-approved analytical kits used for this 2017/2018 report were 5 parts per billion (ppb) for aflatoxins and 0.5 parts per million (ppm) for DON. The FGIS LCL was the same as the lower Limit of Detection (LOD) of 5 ppb and higher than the lower LOD of 0.3 ppm specified for the aflatoxin and DON kits, respectively, used for testing the export samples collected for this survey. Details on the testing methodology employed in this study for the mycotoxins are in the “Testing Analysis Methods” section.
A total of 430 export samples were tested for aflatoxins for the 2017/2018 Export Cargo Report. Results of the 2017/2018 survey testing are as follows:
- Of the 430 samples, 401 samples, or 93.3%, had no detectable levels of aflatoxins (below the FGIS LCL of 5 ppb). This 93.3% is greater than 2016/2017 (80%) and 2015/2016 (90%).
- Aflatoxin levels greater than or equal to 5 ppb, but less than 10 ppb, were found in 25 samples, or 5.8% of the 430 samples tested in 2017/2018. This percentage (5.8%) is less than 2016/2017 (17%) and 2015/2016 (8%).
- Only 4 samples, or 0.9% of the 430 samples tested, in 2017/2018 had aflatoxin levels greater than or equal to 10 ppb, but below or equal to the FDA action level of 20 ppb. This 0.9% is less than 2016/2017 (3%) and 2015/2016 (1%).
- None (0) of the samples tested in 2017/2018 were above the FDA action level of 20 ppb, which is the same as that reported in the 2016/2017 and 2015/2016 Export Cargo Reports.
Similar to 2016/2017 and 2015/2016, 100% of the 2017/2018 export survey sample test results were below the U.S. Food and Drug Administration (FDA) action level of 20 ppb. In addition, the percentage of sample test results below the LCL was significantly greater in 2017/2018 (93.3%) than in 2016/2017 and 2015/2016. As a result, there were fewer incidences (6.7%) in 2017/2018 of sample test results greater than or equal to 5 ppb than in either 2016/2017 (20%) or 2015/2016 (9%). These results suggest that aflatoxin contamination level among lots in the export market was minimal and possibly the lowest in recent crop years. The high percentage of samples that tested below the LCL is probably indicative of the weather conditions during the 2017 growing season that were not conducive for mold growth and aflatoxin formation.
Results: Deoxynivalenol (DON) or Vomitoxin
A total of 430 export samples were tested for DON for the 2017/2018 Export Cargo Report. Results of the testing are shown below:
- DON levels less than 0.5 ppm (the FGIS LCL for DON) were found in 381 samples, or 88.6% of the 430 samples tested. This 88.6% is significantly greater than 2016/2017 (58%), but less than 2015/2016 (99%).
- 47 samples, or 10.9% of the 430 samples tested in 2017/2018, had DON levels greater than or equal to 0.5 ppm, but less than 2.0 ppm. This 10.9% is significantly less than 2016/2017 (42%), but greater than 2015/2016 (1%).
- 2 samples, or 0.5% of the 430 samples tested in 2017/2018, had DON levels greater than or equal to 2.0 ppm, but less than or equal to the FDA advisory level of 5 ppm. This 0.5% for 2017/2018 is only slightly greater than 2016/2017 (0.0%) and 2015/2016 (0.0%).
- None (0) of the 356 export samples tested in 2017/2018 were above the FDA advisory level of 5 ppm, which is the same as that reported in the 2016/2017 and 2015/2016 Export Reports.
Comparison of the 2017/2018 survey results with the 2016/2017 and 2015/2016 survey results indicate there were significantly more DON sample test results below the LCL in 2017/2018 (88.6%) than in 2016/2017 (58%), but slightly fewer than in 2015/2016 (99%). All export survey samples were below or equal to the FDA advisory level of 5 ppm for all three marketing seasons. The large percentage of sample test results below the LCL in 2017/2018 is indicative of weather conditions that were not conducive for mold growth and DON formation.