MDARD Michigan Core Pesticide Applicator Practice Exam

Which pesticide group is known for its irreversible inhibition of cholinesterase?

1. Carbamates

2. Organophosphates

3. Neonicotinoids

4. Herbicides

The correct answer is: Organophosphates

The group of pesticides known for its irreversible inhibition of cholinesterase is the organophosphates. Organophosphates work by binding to the enzyme acetylcholinesterase, which is critical for the normal functioning of the nervous system. This binding is permanent, leading to the accumulation of acetylcholine in the synapses, causing overstimulation of the nervous system and potentially resulting in toxicity in humans and animals. In contrast, carbamates also inhibit cholinesterase, but their inhibition is reversible; the effects can be alleviated once the compound is broken down and the enzyme can return to functioning normally. Neonicotinoids, on the other hand, act primarily on the nervous system by mimicking the neurotransmitter acetylcholine but do not inhibit cholinesterase. Herbicides generally focus on plant growth processes and do not directly act on cholinesterase. Thus, organophosphates stand out as the type of pesticide with irreversible effects on cholinesterase, which is critical for understanding their potential risks and implications for safety.