Environmental Health Program, Saudi Arabia.
Environmental Health Program, Saudi Arabia.
Chemosphere. 2020 Jun;249:126153. doi: 10.1016/j.chemosphere.2020.126153. Epub 2020 Feb 7.
In this study, we determined DNA damage and chromosome breakage (indicators of genotoxicity) and cell viability (an indicator of cytotoxicity) in human lymphoblastoid TK6 and Chinese hamster ovary (CHO) cells treated with 33 e-liquids using in vitro single cell gel (comet), micronucleus (MN), and trypan blue assays, respectively. We also measured the contents of nicotine, five phthalate esters, and DL-menthol in the e-liquids to examine their effects on DNA damage, chromosome breakage, and cell viability. Our chemical analyses showed that: (1) six e-liquids had nicotine ≥2-fold higher than the manufacture's label claim (2-3.5 mg); (2) both dimethyl- and dibutyl-phthalate levels were >0.1 μg/g, i.e., their threshold limits as additives in cosmetics; and (3) the DL-menthol contents ranged from 0.0003 to 85757.2 μg/g, with those of two e-liquids being >1 mg/g, the threshold limit for trigging sensory irritation. Though all the e-liquids induced DNA damage in TK6 cells, 20 resulted in cell viabilities ≤75%, indicating cytotoxicity, yet the inverse relationship between cell viability and DNA damage (r = -0.628, p = 0.003) might reflect their role as pro-apoptotic and DNA damage inducers. Fifteen e-liquids induced MN% in TK6 cells ≥3-fold that of untreated cells. Some of the increase in %MN might be false due to high cytotoxicity, yet six brands showed acceptable cell viabilities (59-71%), indicating chromosome damage. DNA damage and %MN increased when the TK6 cells were exposed to metabolic activation. The CHO cells were less sensitive to the genotoxic effects of the e-liquids than the TK6 cells. DL-menthol was found to be associated with decreased cell viability and increased DNA damage, even at low levels. We cannot dismiss the presence of other ingredients in e-liquids with cytotoxic/genotoxic properties since out of the 63 different flavors, 47 induced DNA damage (≥3-folds), and 26 reduced cell viability (≤75%) in TK6 cells.
在这项研究中，我们使用体外单细胞凝胶（彗星）、微核（MN）和台盼蓝测定法，分别测定了 33 种电子烟液处理的人淋巴母细胞 TK6 和中国仓鼠卵巢（CHO）细胞中的 DNA 损伤和染色体断裂（遗传毒性的指标）以及细胞活力（细胞毒性的指标）。我们还测量了电子烟液中的尼古丁、五种邻苯二甲酸酯和 DL-薄荷醇含量，以检查它们对 DNA 损伤、染色体断裂和细胞活力的影响。我们的化学分析表明：（1）6 种电子烟液中的尼古丁含量是制造商标签声称的 2 至 3.5 倍；（2）二甲基和邻苯二甲酸二丁酯的含量均>0.1μg/g，即它们作为化妆品添加剂的阈值；（3）DL-薄荷醇含量范围为 0.0003 至 85757.2μg/g，其中两种电子烟液的含量>1mg/g，这是引发感官刺激的阈值。尽管所有电子烟液均诱导 TK6 细胞的 DNA 损伤，但有 20 种导致细胞活力≤75%，表明具有细胞毒性，但细胞活力与 DNA 损伤之间的负相关关系（r=-0.628，p=0.003）可能反映了它们作为促凋亡和 DNA 损伤诱导剂的作用。15 种电子烟液诱导 TK6 细胞的 MN%增加≥3 倍于未经处理的细胞。由于高细胞毒性，某些 MN%的增加可能是假阳性的，但 6 个品牌显示出可接受的细胞活力（59-71%），表明染色体损伤。当 TK6 细胞暴露于代谢激活时，DNA 损伤和%MN 增加。与 TK6 细胞相比，CHO 细胞对电子烟液的遗传毒性作用不太敏感。发现 DL-薄荷醇与细胞活力降低和 DNA 损伤增加有关，即使在低水平也是如此。由于在 63 种不同的口味中，有 47 种诱导 DNA 损伤（≥3 倍），26 种降低 TK6 细胞活力（≤75%），因此我们不能排除电子烟液中存在具有细胞毒性/遗传毒性的其他成分。
