Ward Laboratories, Inc analyzes aflatoxin by the Neogen Veratox Quantitative test. Aflatoxins are toxic and carcinogenic substances produced by certain strains of the molds Aspergillus flavus and Aspergillus parasiticus. There are four principle aflatoxins; B1, B2, G1, and G2. Aflatoxin B1 is the most frequently encountered of the group and the most toxic. Corn is the crop generally affected in the Great Plains. The toxicity of aflatoxins to animals range from acute death to chronic disease and interference with reproductive efficiency. Aflatoxins can cause liver damage or cancer, decreased milk and egg production, and immune suppression.
The aflatoxin test is a quantitative test. We charge $24.20 per test. Presently we analyze samples on Friday. We will analyze on any other day when we have accumulated more than 6 samples before Friday.
UN-L IANR has a NebGuide "Grain Molds and Mycotoxins in Corn". This publication should be available from your local Cooperative Extension office. This publication gives some other web sites for obtaining information on corn grain molds. Also, UN-L Cooperative Extension Newsletter, "Crop Watch" has an article on aflatoxins.
Drought stress from pollination to grain fill makes the corn crop vulnerable to Aspergillus mold infection. The greatest infection occurs when day temperature is above 95F and night temperature is above 80F. Excessive high temperature from mid-silk to dough stage is the most critical time of infection. Adequate moisture from rainfall and/or irrigation during this time prevents Aspergillus mold infection. Harvest the corn grain as soon as possible. When harvesting corn grain, turn up the air to blow out damaged and infected kernels. Other factors that may reduce aflatoxin in corn for future years are.
1) Conserve moisture
2) Plant early
3) Avoid excessive planting
4) Use adequate nitrogen
5) Avoid stress
6) Avoid kernel damage (insect control)
7) “Grow grain sorghum”
I believe the aflatoxin test that we run is pretty accurate. Getting a good consistent sample is the biggest problem. I would encourage harvesting some corn grain with a combine to collect a sample. Mold infected lightweight kernels would be blown over during harvest and not in the sample.
FDA tolerance levels for aflatoxin are shown below.

FDA Tolerance Target
0.5 ppb milk
20 ppb dairy
100 ppb mature breeding cattle, swine and poultry
200 ppb finishing swine
300 ppb finishing beef

From NebGuide G00-1408-A.