As electronic cigarettes (e-cigarettes) become increasingly popular smoking devices, there is an increased risk for unintended exposure to e-cigarette liquids through improper disposal resulting in leaching into the environment, third hand vapor exposure through air, or embryonic exposure through maternal vaping. Thus, the safety of e-cigarettes for wildlife and developing embryos need to be thoroughly investigated. We examined perturbations in zebrafish embryonic development after exposures to two cinnamon flavored vaping liquids (with 12 mg/ml nicotine and without nicotine) for e-cigarettes from two different vendors, as well as the flavoring chemical cinnamaldehyde. We focused on the effects of the vaping liquids on hatching success and bone, cartilage and blood vessel development in 3-4 days old transgenic zebrafish larvae. We found that exposures to both of the vaping liquids perturbed the development of the cleithrum and craniofacial cartilage. Exposure to the liquids further caused non-overlapping and partially or completely missing intersegmental vessels. Hatching success was also reduced. Exposure to pure cinnamaldehyde replicated the effects of the vaping liquids with an 50% effect concentration (EC₅₀) of 34-41 µM. Quantification of the amount of cinnamaldehyde in the vaping liquids by mass spectrometry revealed EC₅₀s around 10-40 times lower than for pure cinnamaldehyde, suggesting that additional compounds or metabolites present in the vaping liquids mediate toxicity. Presence of nicotine in one of the vaping liquids decreased its EC₅₀s about two fold compared to the liquid without nicotine. Exposure to the humectants propylene glycol and vegetable glycerin did not affect the vascular, cartilage or bone development in zebrafish embryos. In conclusion, our study shows that exposure to cinnamaldehyde containing vaping liquids causes severe tissue-specific defects in developing embryos.

随着电子烟（e-香烟）成为越来越受欢迎的吸烟装置，通过不当处置导致泄漏到环境中、通过空气接触第三手蒸气或通过母亲吸电子烟导致胚胎接触电子烟液体的风险增加. 因此，需要彻底调查电子烟对野生动物和胚胎发育的安全性。我们检查了斑马鱼胚胎发育在暴露于来自两个不同供应商的电子烟的两种肉桂味电子烟液体（含 12 毫克/毫升尼古丁和不含尼古丁）以及调味化学肉桂醛后的扰动。我们专注于雾化液体对 3-4 天大的转基因斑马鱼幼虫孵化成功和骨骼、软骨和血管发育的影响。我们发现暴露于两种电子烟液体会扰乱睑板和颅面软骨的发育。暴露于液体进一步导致不重叠和部分或完全丢失节间血管。孵化成功率也降低了。暴露于纯肉桂醛中以 50% 的效果浓度（EC₅₀ ) 的 34-41 µM。通过质谱法对电子烟液中肉桂醛的量进行量化显示，EC ₅₀ s 比纯肉桂醛低约 10-40 倍，这表明电子烟液中存在的其他化合物或代谢物介导了毒性。与不含尼古丁的液体相比，其中一种电子烟液体中尼古丁的存在使其 EC ₅₀ s降低了约两倍。接触保湿剂丙二醇和植物甘油不会影响斑马鱼胚胎的血管、软骨或骨骼发育。总之，我们的研究表明，暴露于含有肉桂醛的电子烟液体会导致发育中的胚胎出现严重的组织特异性缺陷。