Tralopyril poisoning due to respiratory exposure

Tralopyril is a metabolite of the pesticide chlorfenapyr. Direct toxicity by tralopyril has not been described. We report two cases of tralopyril poisoning via inhalation.
Two workers developed heat intolerance, diaphoresis, and weight loss after occupational inhalational exposure to tralopyril. Patient 1: The exposure was due to the absence of respiratory protection. Magnetic resonance imaging showed abnormal signals in the bilateral periventricular white matter, corpus callosum, basal ganglia, brainstem, and spinal cord. The patient’s blood tralopyril concentrations on days 1, 3, 5, 8, and 11 post-admission were 1.09 mg/L, 1.04 mg/L, 1.01 mg/L, 0.71 mg/L, and 0.313 mg/L, respectively. Haemoperfusion (HA330), haemoperfusion (HA380), and haemodiafiltration were performed on days 1–3, 5–8, and 9–10, respectively. Patient 2: The patient’s symptoms followed inappropriate use of respiratory protection. His blood tralopyril concentrations on days 1, 4, 5, and 6 were 0.592 mg/L, 0.482 mg/L, 0.370 mg/L, and 0.228 mg/L, respectively.
The patients presented with features typical of chlorfenapyr poisoning, which suggests that tralopyril is the main toxic metabolite of chlorfenapyr.
Tralopyril can be absorbed by inhalation, leading to delayed clinical symptoms and organ damage, including toxic encephalopathy and spinal cord damage.