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Corn Export Cargo Quality Report 2016/2017

Contents

  1. Export Cargo Quality Highlights
  2. Introduction
  3. Quality Test Results
  4. Moisture
  5. Chemical Composition
  6. Physical Factors
  7. Mycotoxins
  8. U.S. Corn Export System
  9. U.S. Corn Export Flow
  10. Impact of the Corn Market Channel on Quality
  11. U.S. Government Inspection and Grading
  12. Survey & Statistical Analysis Methods
  13. Survey Design and Sampling
  14. Statistical Analysis
  15. Testing Analysis Methods
  16. Moisture
  17. Chemical Composition
  18. Physical Factors
  19. Mycotoxin Testing
  20. U.S. Corn Grades And Requirements
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E. MYCOTOXINS

Mycotoxins are toxic compounds produced by fungi that occur naturally in grains. When consumed at elevated levels, mycotoxins may cause sickness in humans and animals. While several mycotoxins have been found in corn grain, aflatoxins and DON (deoxynivalenol or vomitoxin) are considered to be two of the important mycotoxins.
The U.S. grain merchandising industry implements strict safeguards for handling and marketing grain with elevated levels of mycotoxins. All stakeholders in the corn value chain – seed companies, corn growers, grain marketers, and grain handlers, as well as U.S. corn export customers – are interested in understanding how mycotoxin contamination is influenced by growing conditions and the subsequent storage, drying, handling, and transport of the grain as it moves through the U.S. corn export system.
As in the previous Export Cargo Reports, the 2016/2017 export samples were tested for aflatoxins and DON for this year’s report. The accumulation of six years of the Export Cargo Reports is allowing for the evaluation of year-to-year patterns of mycotoxin presence in corn at export points.

Assessing the Presence of Aflatoxins and 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. Details on the testing methodology employed in this study for the mycotoxins are in the “Testing Analysis Methods” section.

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 2016/2017 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.

Results: Aflatoxins

A total of 430 export samples were tested for aflatoxins for the 2016/2017 Export Cargo Report. Results of the 2016/2017 survey testing are as follows:

  • Of the 430 samples, 344 samples, or 80.0%, had no detectable levels of aflatoxins (below FGIS LCL of 5 ppb). This 80.0% is less than 2015/2016 (90%) and 2014/2015 (86%).
  • Aflatoxin levels greater than or equal to 5 ppb, but less than 10 ppb, were found in 71 samples, or 16.5% of the 430 samples tested in 2016/2017. This percentage (16.5%) is greater than 2015/2016 (8%) and 2014/2015 (12%).
  • Only 15 samples, or 3.5% of the 430 samples tested, in 2016/2017 had aflatoxin levels greater than or equal to 10 ppb, but below or equal to the FDA action level of 20 ppb. This 3.5% is greater than 2015/2016 (1%) and 2014/2015 (2%).
  • 100% of the samples tested in 2016/2017 were below or equal to the FDA action level of 20 ppb, which is the same as that reported in the 2015/2016 and 2014/2015 Export Cargo Report..

Similar to 2014/2015 and 2015/2016, 100% of the 2016/2017 export survey test results were below the U.S. Food and Drug Administration (FDA) action level of 20 ppb. However, there were greater incidences in 2016/2017 of sample test results greater than 5 ppb, but less than 10 ppb, than in 2015/2016 and 2014/2015. These results suggest more export lots surveyed in 2016/2017 (16.5%) were found with low levels (greater than 5 ppb, but less than 10 ppb) of aflatoxin contamination than in both 2014/2015 (12%) and 2015/2016 (8%).

Results: DON (Deoxynivalenol or Vomitoxin)

A total of 430 export samples were tested for DON for the 2016/2017 Export Cargo Report. Results of the testing are shown below:

  • DON levels of less than 0.5 ppm (the FGIS LCL for DON) were found in 248 samples, or 57.7% of the 430 samples tested. This 57.7% is less than both 2015/2016 (99%) and 2014/2015 (94%).
  • 182 samples, or 42.3% of the 430 samples tested, had DON levels greater than or equal to 0.5 ppm, but less than 2.0 ppm. This 42.3% is greater than 2015/2016 (1%) and 2014/2015 (6%).
  • No (0) samples, or 0.0% of the 430 samples tested, had DON levels greater than or equal to 2.0 ppm, but less than or equal to the FDA advisory level of 5 ppm. The maximum sample test result observed was 1.3 ppm. This 0.0% is the same as 2015/2016 (0%) and 2014/2015 (0%).
  • None (0) of the 430 2016/2017 export samples tested above the FDA advisory level of 5 ppm, which is the same as that reported in the 2015/2016 and 2014/2015 Export Reports.

Comparison of the 2016/2017 DON export survey results with the 2015/2016 and 2014/2015 DON export survey results indicate more DON incidents in the 2016/2017 export samples than in the samples from the two previous years. The 182 positive incidences (42.3% of the 430 samples surveyed were greater than or equal to 0.5 ppm) were considered to have low levels of contamination with a maximum sample test result of 1.3 ppm. All export survey samples were below or equal to the FDA advisory level of 5 ppm for all three marketing seasons.

Background: General

The levels at which the fungi produce mycotoxins are influenced by the fungus type and the environmental conditions under which the corn is produced and stored. Because of these differences, mycotoxin production varies across the U.S. corn-producing areas and across years. In some years, the growing conditions across the corn-producing regions might not produce elevated levels of any mycotoxins. In other years, the environmental conditions in a particular area might be conducive to production of a particular mycotoxin to levels that impact the corn’s use for human and livestock consumption. Humans and livestock are sensitive to mycotoxins at varying levels. As a result, the FDA has issued action levels for aflatoxins and advisory levels for DON by intended use.

Action levels specify precise limits of contamination above which the agency is prepared to take regulatory action. Action levels are a signal to the industry that FDA believes it has scientific data to support regulatory and/or court action if a toxin or contaminant is present at levels exceeding the action level, if the agency chooses to do so. If imports or domestic feedsupplements are analyzed in accordance with valid methods and found to exceed applicable action levels, they are considered adulterated and may be seized and removed from interstate commerce by FDA.

Advisory levels provide guidance to the industry concerning levels of a substance present in food or feed that are believed by the agency to provide an adequate margin of safety to protect human and animal health. While FDA reserves the right to take regulatory enforcement action, enforcement is not the fundamental purpose of an advisory level.

A source of additional information is the National Grain and Feed Association (NGFA) guidance document titled “FDA Mycotoxin Regulatory Guidance” found at http://www.ngfa.org/wp-content/uploads/NGFAComplianceGuide-FDARegulatoryGuidanceforMycotoxins8-2011.pdf.

Background: Aflatoxins

The most important type of mycotoxin associated with corn grain is aflatoxins. There are several types of aflatoxins produced by different species of Aspergillus, with the most prominent species being Aspergillus (A.) flavus. Growth of the fungus and aflatoxin contamination of grain can occur in the field prior to harvest or in storage. However, contamination prior to harvest is considered to cause most of the problems associated with aflatoxin. A. flavus grows well in hot, dry environmental conditions or where drought occurs over an extended period of time. It can be a serious problem in the southern United States, where hot and dry conditions are more common. The fungus usually attacks only a few kernels on the ear and often penetrates kernels through wounds produced by insects. Under drought conditions, it also grows down silks into individual kernels.

There are four types of aflatoxin naturally found in foods – aflatoxins B1, B2, G1, and G2. These four aflatoxins are commonly referred to as “aflatoxins” or “total aflatoxins.” Aflatoxin B1 is the most commonly found aflatoxin in food and feed and is also the most toxic. Research has shown that B1 is a potent, naturally-occurring carcinogen in animals, with a strong link to human cancer incidence. Additionally, dairy cattle will metabolize aflatoxin to a different form of aflatoxin called aflatoxin M1, which may accumulate in milk.

Aflatoxins express toxicity in humans and animals primarily by attacking the liver. The toxicity can occur from short-term consumption of very high doses of aflatoxin-contaminated grain or long-term ingestion of low levels of aflatoxins, possibly resulting in death in poultry, the most sensitive of the animal species. Livestock may experience reduced feed efficiency or reproduction, and both human and animal immune systems may be suppressed as a result of ingesting aflatoxins.

The FDA has established action levels for aflatoxin M1 in milk intended for human consumption and aflatoxins in human food, grain, and livestock feed products (see table below).

The FDA has established additional policies and legal provisions concerning the blending of corn with levels of aflatoxins exceeding these threshold levels.In general, the FDA currently does not permit the blending of corn containing aflatoxins with uncontaminated corn to reduce the aflatoxin content of the resulting mixture to levels acceptable for use as human food or animal feed.

Corn exported from the United States must be tested for aflatoxins according to federal law. Unless the contract exempts this requirement, testing must be conducted by FGIS. Corn above the FDA action level of 20 ppb cannot be exported unless other strict conditions are met. This results in relatively low levels of aflatoxins in exported grain.

Background: DON (Deoxynivalenol) or Vomitoxin

DON is another mycotoxin of concern to some importers of corn grain. It is produced by a certain species of Fusarium, the most important of which is Fusarium graminearum (Gibberella zeae) which also causes Gibberella ear rot (or red ear rot). Gibberella zeae can develop when cool or moderate and wet weather occurs at flowering. The fungus grows down the silks into the ear, and in addition to producing DON, it produces conspicuous red discoloration of kernels on the ear. The fungus can also continue to grow and rot ears when corn is left standing in the field. Mycotoxin contamination of corn caused by Gibberella zeae is often associated with excessive postponement of harvest and/or storage of high-moisture corn.

DON is mostly a concern with monogastric animals where it may cause irritation of the mouth and throat. As a result, animals may eventually refuse to eat the DON-contaminated corn and may have low weight gain, diarrhea, lethargy, and intestinal hemorrhaging. It may cause suppression of the immune system resulting in susceptibility to a number of infectious diseases.

The FDA has issued advisory levels for DON. For products containing corn, the advisory levels are:

  • 5 ppm in grains and grain co-products for swine, not to exceed 20% of their diet;
  • 10 ppm in grains and grain co-products for chickens and cattle, not to exceed 50% of their diet; and
  • 5 ppm in grains and grain co-products for all other animals, not to exceed 40% of their diet.

FGIS is not required to test for DON on corn bound for export markets, but it will perform either a qualitative or quantitative test for DON at the buyer’s request.