"This raises an important question, which is, who was using that wheat that the FDA considers unfit for human consumption? I worry that my dog is eating a lot of vomitoxin."

From Wikipedia:

Vomitoxin is not a known carcinogen as with aflatoxin. Large amounts of grain with vomitoxin would have to be consumed to pose a health risk to humans.

Companion animals: Dogs and cats are restricted to 5 ppm and of grains and grain byproducts and the grains are not to exceed 40% percent of the diet.