Using Horse Manure In The Garden - Horse Wormer Concerns???

Here is a Cornell Research Paper on ivermectin.  I had a pile sit on a concrete pad for a year even after it was composted for a couple years on the farm.  Found live and fat earth worms in the pile.  My hot humid environment does tend to degrade the chemicals a lot faster.
I followed up with a bean sprout test and found the beans did great. no deformation.