Organophosphates and carbamates inhibit cholinesterase and can poison which organisms?

• A. Insects only
• B. Insects, fish, birds, humans, and other mammals
• C. Plants
• D. Bacteria

Answer: (B)

Organophosphates and carbamates are cholinesterase inhibitors. By blocking acetylcholinesterase, they prevent the breakdown of acetylcholine, causing its buildup at nerve junctions. This leads to excessive and prolonged nerve stimulation, which animals rely on for muscle control and other vital functions. Because many organisms—from insects to other vertebrates—use acetylcholine signaling for their nervous systems, these chemicals can cause poisoning not only in target insects but also in fish, birds, and mammals, including humans, if exposure occurs. Plants don’t have the same nervous systems, and bacteria don’t rely on acetylcholine in the way animals do, so the same mechanism doesn’t translate to those organisms. That broad potential impact is why the statement including insects, fish, birds, humans, and other mammals is the best answer.