Transient facial sensory symptoms following exposure to synthetic pyrethroids: a clinical and electrophysiological assessment.

Amongst twenty-three workers exposed to synthetic pyrethroids, ninteen had experienced one or more episodes of abnormal facial sensation, developing between thirty min and three hr after exposure and persisting for thirty min to eight hr. There were no abnormal neurological signs and electrophysiological studies were normal in the arms and legs. It is concluded that the symptoms are most likely to be due to transient lowering of the threshold of sensory nerve fibres or sensory nerve endings following exposure of the facial skin to pyrethroids, similar to the phenomena that have been described following exposure of animal nerves to pyrethroids.