Drought 2012 and aflatoxin: What you need to know

High temperatures and a lack of precipitation aren’t the only issues plaguing farmers this year – the drought also has led to an outbreak of a carcinogenic mycotoxin – aflatoxin.

Aflatoxin is produced by certain strains of the mold Aspergillus, which flourishes in hot and dry conditions such as those created by this summer’s drought. Ingesting excessive amounts of aflatoxin can cause chronic health problems, including liver damage or cancer, decreased milk and egg production, immune suppression and reduced reproductive efficiency. With confirmed reports of aflatoxin in more than eight states ranging from Texas to South Carolina, testing is more important than ever.

Obtaining a representative sample is critical when testing for aflatoxin, a task that is difficult in large containers such as hopper cars and barges. Since mycotoxin contamination typically is not evenly distributed throughout a load, it is difficult to get an accurate representation without a significant sample size. To obtain a representative sample, use the appropriate probe size for gathering the sample (which is dependent on the type of container used to transport the grain) and ensure the number of samples taken also is appropriate for the container. The Grain Inspection, Packers and Stockyards Administration (GIPSA) recommends following the guidelines below to obtain a representative sample:

Carrier Probe length Probes per compartment
Barges 12 feet 1
Hopper car 10—12 feet 1
Boxcar 6 feet 5
Truck 5—6 feet 7
Hopper-bottom car 6—10 feet 2
For more information, visit www.gipsa.usda.gov/fgis/insp_weigh/sampling.html

Once a representative sample of 3 to 5 lbs is obtained, blend the sample through a multichannel grain divider. Grind the sample to a fine consistency (e.g., 75 percent passes through a 20 mesh screen).

Neogen has several tests to detect aflatoxin. For a full list, click here.

Remember, unlike the fungi that produce them, mycotoxins are chemical substances that are not alive and therefore cannot be killed. There are no proven treatments to neutralize a mycotoxin while preserving the integrity of the contaminated commodity.

Many people often ask if black lights detect aflatoxin in corn. Studies have shown that this method produce unreliable results as the bright yellow-green fluorescence produced by a black light detects the presence of kojic acid, not aflatoxin. Kojic acid is a by-product of Aspergillus flavus, which can produce the acid without producing aflatoxin. The other major producer of aflatoxin, Aspergillus parasiticus, does not produce kojic acid, making the black light method an unreliable indicator of aflatoxin contamination.

The U.S. Food and Drug Administration has issued regulatory levels for aflatoxin as follows:

For Level Commodities
Humans 20 ppb All foods except milk
All animal species 20 ppb All feed (exceptions below)
Breeding cattle, breeding swine, mature poultry 100 ppb Corn
Finishing swine (>100 lbs) 200 ppb Corn
Finishing beef cattle 300 ppb Corn
Finishing beef cattle, swine, poultry 300 ppb Cottonseed meal

For a full list of aflatoxin testing products, click here.

Fora  list of other Neogen blog posts pertaining to aflatoxin click here. For other drought posts, click here.

For our weekly mycotoxin update,  click here.

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