Abstract

Neonicotinoid is a new class of systemic insecticides that are selectively toxic to insects. However, cases of human toxicity have been reported. A man in his 60s, who worked as a pest control operator (which required the use of thiamethoxam), presented with fever and headache. We investigated the levels of thiamethoxam and clothianidin in the blood and urine. Our results suggested that chronic thiamethoxam intoxication was caused by occupational inhalation exposure and environmental pollution. After cessation of insecticide use, the patient remained asymptomatic but had persistent oral dysesthesia and postural finger tremor, even at undetectable levels of thiamethoxam and clothianidin. This case report is the first to describe human thiamethoxam intoxication after occupational inhalation exposure. When similar symptoms are encountered and a history of insecticide use is confirmed, clinicians should consider the diagnosis of neonicotinoid intoxication.