i personally wouldnt want to smoke anything that was treated in anyway with a chemical spray, even if it was directly on the plant, within a week of harvest...
ever watch "1000 ways to die"? maybe you could get on an episode wouldnt risk it. i got poisoned about 15 years ago. spent a month in the hospital and almost died. it was caused by a non poisonous substance getting heated up and turning into a deadly toxin used for chem warfare in ww1. anyway, burning chemicals can turn something harmless into something deadly even if it isnt poison out of the bottle.