Non-authoritarian solution is to have certification. It will be up to consumer to buy only food certified by PureFood.
Besides, my tomatoes are certified safe by Nutr-Alert and SafeCo. SafeCo even lets me doctor the lab results myself, for a little extra! I'm still in negotiation with PureFood, but I'm sure this little speedbump will be ironed out before you know it. Iron is good for you, anyway; they don't even test for that.