Not GP but (former) chemist, and I share the same sentiment. Paraquat scares me. Note its direct chemical similarity to MPP+ [0], both sporting that methylpyrid

Not GP but (former) chemist, and I share the same sentiment. Paraquat scares me. Note its direct chemical similarity to MPP+ [0], both sporting that methylpyridinium moeity (the CH3N+ in the ring). In fact the only real difference is paraquat is a two-for-one on neurotoxic functional group. Glyphosate gets a bad rap in large part due to similarity to organophosphates (P-O-C), which are usually quite toxic, but it is in fact a phosphonate, with a direct P-C bond. I forget the exact mechanism, but it makes a difference. Also glyphosate readily hydrolyzes, while paraquat is a "brick" that resists breakdown and is prone to bioaccumulation. The mechanism of action is identical: methylpyridinium promotes the production of reactive oxygen species which wreak havoc on cellular machinery. In fact MPP is a "quat" and was briefly used as an herbicide. The chloride of MPP+ was sold under the trade name Cyperquat. > As an herbicide, paraquat acts by inhibiting photosynthesis. In light-exposed plants, it accepts electrons from photosystem I (more specifically ferredoxin, which is presented with electrons from PS I) and transfers them to molecular oxygen. In this manner, destructive reactive oxygen species (ROS) are produced. > MPP+ exhibits its toxicity mainly by promoting the formation of reactive free radicals in the mitochondria of dopaminergic neurons in the substantia nigra.[9][10] MPP+ can siphon electrons from the mitochondrial electron transport chain at complex I and be reduced, in the process forming radical reactive oxygen species which go on to cause further, generalized cellular damage. [0] - https://en.m.wikipedia.org/wiki/MPP%2B https://en.m.wikipedia.org/wiki/MPP%2B