What group of insecticides interferes with the nervous system of humans?

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

Answer: (A)

Organophosphates interfere with human nervous system signaling by irreversibly inhibiting acetylcholinesterase, the enzyme that normally breaks down acetylcholine in synapses. When this enzyme is blocked, acetylcholine builds up, causing continuous stimulation of nerves throughout the body. That widespread cholinergic overstimulation produces strong symptoms such as excessive salivation, sweating, urination, diarrhea, constricted pupils, muscle twitching, weakness, and potentially dangerous breathing difficulties. Because the inhibition is long-lasting, exposure can lead to a rapid, severe cholinergic crisis if not treated promptly.

Other insecticide groups differ in how they affect nerves. Pyrethroids disrupt nerve impulses by keeping sodium channels open, which can cause irritability or tremors in humans but are typically much less dangerous overall. Carbamates also inhibit acetylcholinesterase but do so reversibly, so their effects wear off more quickly than organophosphates. Neonicotinoids target nicotinic acetylcholine receptors primarily in insects, with far lower impact on human receptors, making them less likely to cause the same kind of nervous-system disruption seen with organophosphates.