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Thiamethoxam intoxication due to occupational inhalational exposure
  1. Toshinori Nishizawa1,2,
  2. Yoshinori Ikenaka3,4,
  3. Go Ichikawa5 and
  4. Tomohiro Taguchi6,7
  1. 1Department of General Internal Medicine, St. Luke's International Hospital, Tokyo, Japan
  2. 2Department of Global Health Promotion, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
  3. 3Translational Research Unit, Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
  4. 4Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
  5. 5Department of Pediatrics, Ustunomiya Cerebrospinal Center, Utsunomiya City, Japan
  6. 6Department of Community Based Medicine, Fujita Health University, Toyoake, Japan
  7. 7Department of General Internal Medicine, Toyota Regional Medical Center, Toyota, Japan
  1. Correspondence to Dr Toshinori Nishizawa; nishizawa.toshinori{at}


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.

  • General practice / family medicine
  • Exposures
  • Occupational and environmental medicine

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  • Contributors TN and TT cared for the patient and wrote the report. YI performed the concentration measurement. GI provided professional advice. All authors read and approved the final version of the report.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.