Chemical of the Week – Ronnel

Ronnel is an organophosphate insecticide that’s fallen out of mainstream use but still lurks in agricultural settings, veterinary applications, and older pest control stockpiles where it can ambush unsuspecting responders who aren’t expecting to encounter a cholinesterase inhibitor. This white to tan crystalline solid was once widely used for livestock pest control (particularly cattle grubs and flies), but like its more notorious cousins in the organophosphate family, ronnel works by shutting down acetylcholinesterase, the enzyme that keeps your nervous system functioning properly. The good news is that ronnel is less acutely toxic than many other organophosphates; the bad news is that “less toxic” still means it can cause the full spectrum of cholinergic crisis symptoms including excessive salivation, sweating, muscle twitching, respiratory distress, and potentially death at sufficient doses. The real trap with ronnel is complacency: responders familiar with modern, less toxic pesticides might not recognize the signs of organophosphate poisoning or understand the need for atropine and pralidoxime (2-PAM) in severe exposures. Whether you’re dealing with an agricultural spill, exposure at a veterinary facility, discovery of old pesticide stocks, or a suspected poisoning, treat ronnel with the same respect you’d give any organophosphate: use appropriate PPE including respiratory protection, decontaminate thoroughly, monitor for delayed symptom onset, and ensure medical responders know they’re dealing with a cholinesterase inhibitor that may require specific antidotes. Don’t let ronnel’s relative obscurity or lower toxicity compared to parathion fool you into casual handling.

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