Associate Certified Entomologist (ACE) Practice Exam

Which symptom is likely to occur due to organophosphate exposure?

1. Increased energy levels

2. Severe headaches

3. Continuous muscle contraction

4. Dry mouth

The correct answer is: Continuous muscle contraction

Continuous muscle contraction is a symptom often associated with organophosphate exposure due to their mechanism of action as acetylcholinesterase inhibitors. Organophosphates interfere with the normal breakdown of the neurotransmitter acetylcholine in the synaptic cleft. When acetylcholine is not properly degraded, it accumulates, leading to overstimulation of the muscles and resultant symptoms like continuous muscle contraction, also known as muscle twitching or spasms. This is a hallmark sign of organophosphate poisoning and is rooted in the disruption of the normal neuromuscular function. In contrast, increased energy levels would not be a typical symptom of organophosphate exposure; rather, it usually results in fatigue and weakness. Severe headaches may occur due to various reasons in toxic exposure scenarios but are not specific to organophosphates. Dry mouth can be seen in anticholinergic poisoning but not in the context of organophosphate exposure, where excessive cholinergic activity typically leads to the opposite effect, such as increased salivation.