1,1-Difluoroethane (DFE) is a halogenated hydrocarbon that is commonly used as a propellant in air duster products. Herein, the pharmacology of DFE was reviewed, and questions relevant to medicolegal investigations were addressed. Particular emphasis was given to detection time in biological specimens and the range, onset and duration of effects. DFE may be abused as an inhalant and is rapidly absorbed through the lungs. Onset of central nervous system (CNS) depressant effects is within seconds and the duration may only last minutes. The effects may lead to impairment of human performance, including confusion, lethargy, impaired judgment, loss of motor coordination and loss of consciousness. Death may result even after the first use. With heavy use or in combination with other CNS depressants, extended periods of drowsiness or loss of consciousness may be observed with an increased risk of a fatal event. A majority of impaired driving investigations where DFE was identified included a collision demonstrating the significant impact its use may have on traffic safety. When DFE is identified alone, without other drugs that cause CNS impairment, the effects may not be observable minutes after the crash, making identification of its use difficult. Although concentrations dissipate rapidly, DFE has been detected in blood specimens collected up to 3 hours after the driving incident. Two studies on passive exposure presented herein demonstrated that it is unlikely to detect DFE above concentrations of ∼2.6 µg/mL in blood or urine due to even extreme unintentional exposure. Alternative specimens such as brain, lung and tracheal air should be considered in some postmortem investigations. DFE has been identified in blood specimens from postmortem cases at concentrations from 0.14 to 460 µg/mL and in impaired driving cases from 0.16 to 140 µg/mL.

中文翻译：

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毒理学家和病理学家的 1,1-二氟乙烷法医方面

1,1-二氟乙烷 (DFE) 是一种卤代烃，通常用作空气除尘产品中的推进剂。本文回顾了 DFE 的药理学，并解决了与法医调查相关的问题。特别强调了生物样本的检测时间以及影响的范围、开始和持续时间。DFE 可能被滥用为吸入剂，并通过肺部迅速吸收。中枢神经系统 (CNS) 抑制作用在几秒钟内开始出现，持续时间可能仅持续几分钟。这些影响可能导致人类表现受损，包括混乱、嗜睡、判断力受损、运动协调丧失和意识丧失。即使在第一次使用后也可能导致死亡。大量使用或与其他中枢神经系统抑制剂联合使用，长时间的嗜睡或意识丧失可能会增加致命事件的风险。大多数发现 DFE 的受损驾驶调查都包括一次碰撞，证明其使用可能对交通安全产生重大影响。当单独识别 DFE 时，没有其他导致 CNS 损伤的药物，其影响可能在碰撞后数分钟内无法观察到，因此难以识别其使用情况。尽管浓度迅速消散，但在驾驶事故发生后 3 小时内采集的血液样本中仍检测到 DFE。本文介绍的两项关于被动暴露的研究表明，即使是极端的无意暴露，也不太可能在血液或尿液中检测到浓度高于 2.6 µg/mL 的 DFE。替代标本，例如大脑，在一些死后检查中应考虑肺和气管空气。DFE 在死后病例的血液样本中的浓度为 0.14 至 460 µg/mL，在驾驶受损病例中的浓度为 0.16 至 140 µg/mL。