When I was young my grandma told me an interesting rule of thumb from her childhood in the old country:
If there are no bugs in the grain after it has been stored for a while, don't eat it.
The rationale was that if bugs didn't want to eat it (they didn't have tightly sealed packaging at that time), it was probably chemically contaminated.
If there are no bugs in the grain after it has been stored for a while, don't eat it.
The rationale was that if bugs didn't want to eat it (they didn't have tightly sealed packaging at that time), it was probably chemically contaminated.