I worked for a landscape company that used paraquat, the year was about 1985. I remember that the tank that was used to hold this stuff (in mixed form) was on the lot. I didn't know what was in it but I put my head and had a whiff. Someone came running up and said 'what are you doing!!???" if I hadn't cleaned the tank out you would be dead, there was paraquat in there half hour ago!!!
I started to get scared at the thought that death could have had me at the moment. Paraquat is bad stuff.
But good to kill weeds!!!
I once smoked some weed that rumoured to have had paraquat sprayed on it, it made me sick as a dog.
The mind is like a parachute, it only functions when it is open.