Agree with Dave's statement that illegal pesticides have been used in a marijuana farm for profit. Also, draw a comparison between marijuana farms and tobacco producers when it comes to using chemicals that may negatively impact consumers' health.
You are spot on Dave.  They have already been caught using illegal pesticides more than once.   Consider this, you have a legal pot farm that is indoors and the size of a football stadium; so you are growing about $5-10million at any given time...what are the chances you will not be ensuring no pests or other maladies occur by spraying the crap out of it.  Do you think Tobacco producers took your health into consideration when they started putting chemicals in their products....no they care about their bottom line.