Pesticides have a high affinity to the cholinesterase enzyme in the human body. Which class is typically associated?

• A. Organophosphate
• B. Carbamate
• C. Pyrethroid
• D. Organochlorine

Answer: (A)

Pesticides that strongly inhibit acetylcholinesterase do so by organophosphates, which phosphorylate the enzyme’s active site and create persistent inhibition. This leads to accumulation of acetylcholine at cholinergic synapses and widespread overstimulation of both muscarinic and nicotinic receptors. Carbamates can also inhibit acetylcholinesterase, but their effect is reversible and shorter‑acting, so they don’t exhibit the same high‑affinity, long‑lasting inhibition. Pyrethroids and organochlorines affect other nervous system targets (sodium channels and GABA receptors, respectively) rather than primarily inhibiting acetylcholinesterase. So the class most associated with high-affinity cholinesterase inhibition is organophosphates.