Relationship between Urinary N-Desmethyl-Acetamiprid and Typical Symptoms including Neurological Findings: A Prevalence Case-Control Study

Neonicotinoid insecticides are nicotinic acetylcholine receptor agonists used worldwide. Their environmental health effects including neurotoxicity are of concern. We previously determined a metabolite of acetamiprid, N-desmethyl-acetamiprid in the urine of a patient, who exhibited some typical symptoms including neurological findings. We sought to investigate the association between urinary N-desmethyl-acetamiprid and the symptoms by a prevalence case-control study. Spot urine samples were collected from 35 symptomatic patients of unknown origin and 50 non-symptomatic volunteers (non-symptomatic group, NSG, 4–87 year-old). Patients with recent memory loss, finger tremor, and more than five of six symptoms (headache, general fatigue, palpitation/chest pain, abdominal pain, muscle pain/weakness/spasm, and cough) were in the typical symptomatic group (TSG, n = 19, 5–69 year-old); the rest were in the atypical symptomatic group (ASG, n = 16, 5–78 year-old). N-desmethyl-acetamiprid and six neonicotinoids in the urine were quantified by liquid chromatography-tandem mass spectrometry. The detection of N-desmethyl-acetamiprid was the most frequent and highest in TSG (47.4%, 6.0 ppb (frequency, maximum)), followed by in ASG (12.5%, 4.4 ppb) and in NSG (6.0%, 2.2 ppb), however acetamiprid was not detected. Thiamethoxam was detected in TSG (31.6%, 1.4 ppb), in ASG (6.3%, 1.9 ppb), but not in NSG. Nitenpyram was detected in TSG (10.5%, 1.2 ppb), in ASG (6.3%, not quantified) and in NSG (2.0%, not quantified). Clothianidin was only detected in ASG (6.3%, not quantified), and in NSG (2.0%, 1.6 ppb). Thiacloprid was detected in ASG (6.3%, 0.1 ppb). The cases in TSG with detection of N-desmethyl-acetamiprid and thiamethoxam were aged 5 to 62 years and 13 to 62 years, respectively. Detection of N-desmethyl-acetamiprid was associated with increased prevalence of the symptoms (odds ratio: 14, 95% confidence interval: 3.5–57). Urinary N-desmethyl-acetamiprid can be used as a biomarker for environmental exposure to acetamiprid. Further multi-centered clinical research in larger patients groups with more metabolites analysis is needed.

新烟碱类杀虫剂（Neonicotinoid insecticides）是全球广泛应用的烟碱型乙酰胆碱受体（nicotinic acetylcholine receptor）激动剂，其对环境与健康的影响（包括神经毒性）备受关注。此前我们曾在1名出现包括神经系统异常在内的典型症状的患者尿液中，检出啶虫脒（acetamiprid）的代谢物N-去甲基啶虫脒（N-desmethyl-acetamiprid）。本研究旨在通过现患病例对照研究，探讨尿液中N-去甲基啶虫脒与相关症状之间的关联。本研究收集了35名病因不明的症状患者与50名无症状志愿者的即时尿样：无症状组（non-symptomatic group, NSG）的年龄范围为4~87岁。同时出现近期记忆减退、手指震颤，且满足6项症状（头痛、全身乏力、心悸/胸痛、腹痛、肌肉疼痛/无力/痉挛及咳嗽）中5项及以上的患者被归入典型症状组（typical symptomatic group, TSG，n=19，年龄范围5~69岁）；其余患者则被归入非典型症状组（atypical symptomatic group, ASG，n=16，年龄范围5~78岁）。本研究采用液相色谱-串联质谱法（liquid chromatography-tandem mass spectrometry）对尿液中的N-去甲基啶虫脒与6种新烟碱类杀虫剂进行定量检测。N-去甲基啶虫脒的检出率与最高检出浓度在典型症状组中最高：检出率为47.4%，最高浓度达6.0 ppb，其次为非典型症状组（12.5%，4.4 ppb）与无症状组（6.0%，2.2 ppb）；但本研究未检出啶虫脒。噻虫嗪（Thiamethoxam）在典型症状组中的检出率为31.6%，最高浓度1.4 ppb；非典型症状组检出率6.3%，最高浓度1.9 ppb；无症状组未检出噻虫嗪。烯啶虫胺（Nitenpyram）在典型症状组中的检出率为10.5%，最高浓度1.2 ppb；非典型症状组检出率6.3%，未定量；无症状组检出率2.0%，未定量。噻虫胺（Clothianidin）仅在非典型症状组（检出率6.3%，未定量）与无症状组（检出率2.0%，最高浓度1.6 ppb）中检出。噻虫啉（Thiacloprid）在非典型症状组中的检出率为6.3%，最高浓度0.1 ppb。典型症状组中检出N-去甲基啶虫脒与噻虫嗪的患者年龄分别为5~62岁与13~62岁。尿液中检出N-去甲基啶虫脒与症状发生率升高显著相关（优势比OR=14，95%置信区间CI=3.5~57）。尿液中的N-去甲基啶虫脒可作为啶虫脒环境暴露的生物标志物。未来需开展更大样本量患者队列的多中心临床研究，并增加更多代谢物的检测分析。