A case of human poisoning with a flufenoxuron-containing insecticide

Flufenoxuron is a recently introduced insecticide. The compound is known to exert its insecticidal activity by inhibiting chitin synthesis in insects. However, its toxic effects on humans are unknown.

A 72-year-old woman was brought to the emergency department by ambulance. The person accompanying her brought an empty 100-mL bottle of an insecticide (Cascade), which was found at the scene. The active ingredient of the product is flufenoxuron and the other components include surfactants and solvents. A detailed composition obtained from the manufacturer was flufenoxuron, ethoxylated nonylphenol phosphate, polyoxyethylene nonylphenol, N-methyl-2-pyrrolidone, and cyclohexanone. Upon arrival at the intensive care unit (ICU), her arterial pH was 7.093, her bicarbonate level was 7.4 mEq/L, and the anion gap was 33.8 mEq/L. Her lactic acid concentration was 16.5 mmol/L. Lactic acidosis was not considered to be a consequence of circulatory shock, because there was no clinical sign of shock other than lactic acidosis, and cardiac output was never below 4.5 L/min. Her acid-base status began to improve and returned to near normal on the next day.

It can be hypothesized that the toxicity of the product includes inhibition of the oxygen utilization mechanism at the cellular level. The product is composed of a number of components, similar to many other herbicide products. It is not possible to identify which of the ingredients was specifically responsible for the toxic effects in this case.