Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China.
Environ Health Perspect. 2020 Mar;128(3):36001. doi: 10.1289/EHP5686. Epub 2020 Mar 18.
Electronic cigarettes (e-cigarettes) have become popular, in part because they are perceived as a safer alternative to tobacco cigarettes. An increasing number of studies, however, have found toxic metals/metalloids in e-cigarette emissions.
We summarized the evidence on metal/metalloid levels in e-cigarette liquid (e-liquid), aerosols, and biosamples of e-cigarette users across e-cigarette device systems to evaluate metal/metalloid exposure levels for e-cigarette users and the potential implications on health outcomes.
We searched PubMed/TOXLINE, Embase®, and Web of Science for studies on metals/metalloids in e-liquid, e-cigarette aerosols, and biosamples of e-cigarette users. For metal/metalloid levels in e-liquid and aerosol samples, we collected the mean and standard deviation (SD) if these values were reported, derived mean and SD by using automated software to infer them if data were reported in a figure, or calculated the overall mean (mean ± SD) if data were reported only for separate groups. Metal/metalloid levels in e-liquids and aerosols were converted and reported in micrograms per kilogram and nanograms per puff, respectively, for easy comparison.
We identified 24 studies on metals/metalloids in e-liquid, e-cigarette aerosols, and human biosamples of e-cigarette users. Metal/metalloid levels, including aluminum, antimony, arsenic, cadmium, cobalt, chromium, copper, iron, lead, manganese, nickel, selenium, tin, and zinc, were present in e-cigarette samples in the studies reviewed. Twelve studies reported metal/metalloid levels in e-liquids (bottles, cartridges, open wick, and tank), 12 studies reported metal/metalloid levels in e-cigarette aerosols (from cig-a-like and tank devices), and 4 studies reported metal/metalloid levels in human biosamples (urine, saliva, serum, and blood) of e-cigarette users. Metal/metalloid levels showed substantial heterogeneity depending on sample type, source of e-liquid, and device type. Metal/metalloid levels in e-liquid from cartridges or tank/open wicks were higher than those from bottles, possibly due to coil contact. Most metal/metalloid levels found in biosamples of e-cigarette users were similar or higher than levels found in biosamples of conventional cigarette users, and even higher than those found in biosamples of cigar users.
E-cigarettes are a potential source of exposure to metals/metalloids. Differences in collection methods and puffing regimes likely contribute to the variability in metal/metalloid levels across studies, making comparison across studies difficult. Standardized protocols for the quantification of metal/metalloid levels from e-cigarette samples are needed. https://doi.org/10.1289/EHP5686.
电子烟作为一种烟草替代品，由于其被认为更为安全，因此受到广泛欢迎。然而，越来越多的研究发现电子烟的排放物中含有有毒金属/类金属。
本研究旨在总结电子烟液体（e-liquid）、气溶胶和电子烟使用者生物样本中金属/类金属水平的证据，以评估电子烟使用者的金属/类金属暴露水平及其对健康结果的潜在影响。
我们检索了 PubMed/TOXLINE、Embase®和 Web of Science 中关于电子烟液体、电子烟气溶胶和电子烟使用者生物样本中金属/类金属的研究。对于电子烟液体和气溶胶样本中的金属/类金属水平，如果这些值有报告，则收集平均值和标准差（SD）；如果数据以图形形式报告，则使用自动软件推断平均值和标准差；如果仅为单独的组报告数据，则计算总体平均值（平均值±SD）。为了便于比较，将电子烟液体和气溶胶中的金属/类金属水平分别转换并报告为每千克微克和每口纳克。
我们共检索到 24 项关于电子烟液体、电子烟气溶胶和电子烟使用者生物样本中金属/类金属的研究。在综述的研究中，电子烟样本中存在铝、锑、砷、镉、钴、铬、铜、铁、铅、锰、镍、硒、锡和锌等金属/类金属。12 项研究报告了电子烟液体（瓶、盒、开放式 Wick 和罐）中的金属/类金属水平，12 项研究报告了电子烟气溶胶（来自 cig-a-like 和罐式装置）中的金属/类金属水平，4 项研究报告了电子烟使用者生物样本（尿液、唾液、血清和血液）中的金属/类金属水平。金属/类金属水平因样本类型、电子烟液体来源和装置类型而异，存在显著异质性。从盒式或罐式/开放式 Wick 中提取的电子烟液体中的金属/类金属水平高于从瓶式电子烟液体中的水平，这可能是由于线圈接触所致。在电子烟使用者的生物样本中发现的大多数金属/类金属水平与在传统香烟使用者的生物样本中发现的水平相似或更高，甚至高于在雪茄烟使用者的生物样本中发现的水平。
电子烟是金属/类金属暴露的潜在来源。收集方法和抽吸模式的差异可能导致不同研究中金属/类金属水平的差异，使得跨研究比较变得困难。需要标准化的协议来定量电子烟样本中的金属/类金属水平。
