Aflatoxin: What is it, and why worry?

Doug Jardine

Professor

Kansas State University

Aflatoxin facts

• Aflatoxins are metabolic products produced by the fungus Aspergillus flavus and several other species of Aspergillus

• They are most often found in corn, peanuts, cottonseed, brazil nuts and fishmeal

• Symptoms of mycotoxicoses

– Pregnant cows, calves, young pigs and sheep fed long term low dosages develop: • intestinal bleeding,

• debilitation

• reduced growth

• nausea

• refusal to feed

• spontaneous abortions

• susceptibility to other diseases

Aflatoxin facts

– Poultry

• Reduced production performance, egg production and egg weight

• Poor carcass quality

• Immunosuppression

• Increased mortality

• Increased leg problems

• Pale bird syndrome

Aflatoxin facts

• The toxin accumulates in the liver and often causes liver cancer

Aflatoxin facts

When is it a problem?

• Aspergillus is most serious in years when high temperatures and droughty conditions stress plants

• Insect damage can also predispose the kernels to fungal penetration

What does it look like?

• Aspergillus forms on the ears late in the season as an olive green mold

• Feeding damage from insects provide additional points of entry for the fungus

2011 aflatoxin situation

• Kansas Grain Inspection Service – Wichita – Received close to 4,000 samples, mostly from

insurance adjusters (400 would be normal)

– 75% tested over the 20 ppb human use limit

– 15% were over 100 ppb

– Only a handful were over the 300 ppb non-usage limit

• Highest reported level from southeast Kansas was ~1,200 ppb

What is the current situation?

• Similar weather is making for similar problems

• Field incidence of Aspergillus is similar to 2011 levels • Early reports indicate that most samples are below

100 ppb

• Much of the dryland corn is being chopped for silage or baled for hay

Testing for Aflatoxin

• Black light tests

• Thin layer chromatography

• Rapid one step assays

What is a black light test?

• A black light test is used for detection by placing cracked corn kernels under short wave ultraviolet light

• Aspergillus produces a by-product known as kojic acid which fluoresces bright greenish-yellow under UV light

• Since kojic acid and aflatoxin are produced independently of each other by the fungus, it is a poor test for aflatoxin presence

– e.g. kojic acid may be present, but not aflatoxin or aflatoxin may be present, but not kojic acid

Black light test

Thin layer chromatography

• Requires highly specialized and expensive equipment and is used mostly in research labs

Rapid One Step Assays

• Fast Aflatoxin Quantitative Tests – Results in 3 to 10

minutes

– Uses 50% ethanol or methanol for extraction

– Reads from 0 to 150 ppb

• Suppliers include Charms, Neogen, Envirologix, VICAM

Sampling method is critical for accuracy

• Aflatoxin tends to be localized within a lot of grain so composite sampling should be done

Sampling

• Procedure 1

– The best procedure is to take periodic samples from a moving grain stream and combine them into a sample of at least 10 pounds

Sampling

• Procedure 2

– Sample with a probe through a storage unit (five perimeter samples and one center sample for each 6 feet of bin height)

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6 6 6

Sampling

For best accuracy, grain trucks should have samples taken from multiple locations within the load.

What to do with contaminated grain

• Uses are based on level of contamination

Since aflatoxin levels concentrate by 3-4 fold in distiller grains, ethanol plants generally will not except contaminated grain.

• Keep in mind these are guidelines. Most buyers will have guidelines far more stringent than the FDA guidelines

– E.g. One pet food manufacturer indicated they would not accept corn over 8 ppb

– Human food processors are likely to be even more stringent

FDA Regulatory Guidance for Toxins and Contaminants

• The Food and Drug Administration has issued regulatory guidance for two toxins and contaminants that may be present in raw grains and finished feed: Aflatoxin and deoxynivalenol (vomitoxin).

http://www.ngfa.org/files/misc/Guidance_for_Toxins.pdf

What can be done with contaminated grain that is outside FDA guidelines

• FDA Blending Policy: Importantly, with respect to aflatoxin, FDA currently generally does not permit corn containing aflatoxin to be blended with uncontaminated corn to reduce the aflatoxin content of the resulting mixture to levels acceptable for use as human food or animal feed. However, on occasion FDA has relaxed its “no-blending” policy in response to widespread outbreaks of aflatoxin or in response to state-specific requests to address local outbreaks.

What constitutes blending • FDA technically does not consider mixing of corn containing a level

of aflatoxin up to the action level considered to be “acceptable” for a given species to be a violation of its “no-blending” policy.

• For example, since corn containing aflatoxin of up to 300 ppb that is intended to be fed to mature beef cattle does not violate FDA’s action level, technically any corn containing less than 300 ppb can be mixed and fed to that species without violating the “no-blending” policy.

• But mixing corn containing up to 200 ppb with uncontaminated corn (less than 20 ppb) so as to reduce the level of aflatoxin in the resulting mixture to 50 ppb so it could be fed to laying hens constitutes a violation of the “no-blending” policy since a 100 ppb action level applies to mature poultry.

Ammoniation

• Detoxification Policy for Aflatoxin: Currently, there is no FDA- approved nor sanctioned method for “detoxifying” – through ammoniation or other means -- corn that contains aflatoxin.

• Ammoniation is for detoxifying cottonseed only

Other considerations

1. Clean bins and grain handling equipment

– remove fines from the corn before storing

2. Regulate grain moisture

– Moldy corn should be dried to 15% moisture or less

– For long term storage dry to 13-14% moisture

Other considerations

3. Cool grain to 35-40 F as soon as feasible

– In spring warm grain to 50-60 F to prevent condensation.

4. Control storage insects

5. Check grain every 2 weeks in storage – Check for temperature, crusting, hot spots, moisture,

and mold. Take corrective measures as needed.

Thank You

Questions?