電子たばこは有害化学物質曝露を減らし禁煙を支援（Nicotine e-cigarettes reduce harmful chemical exposure, help smokers quit）

2026-05-20

2026-05-19 ペンシルベニア州立大学（Penn State）

米ペンシルベニア州立大学の研究チームは、ニコチン入り電子たばこ（e-cigarettes）が、従来の紙巻きたばこ喫煙者において有害化学物質への曝露を減少させ、禁煙支援にも役立つ可能性を示した。研究では、紙巻きたばこから電子たばこへ切り替えた喫煙者を対象に、生体内の有害化学物質指標や禁煙継続状況を分析した。その結果、発がん性物質や有毒化学物質への曝露レベルが低下し、一部参加者では禁煙成功率向上も確認された。研究チームは、電子たばこが完全に安全ではないものの、燃焼を伴う従来喫煙より有害物質生成が少ない点を指摘している。一方で、若年層への普及やニコチン依存継続リスクには注意が必要であり、長期的健康影響についてはさらなる検証が必要だとしている。成果は、禁煙支援政策やたばこ害低減（harm reduction）戦略に関する議論へ重要な科学的知見を提供するものとされる。

＜関連情報＞

紙巻きタバコからポッド型電子タバコに切り替えた後の有害物質への曝露無作為化臨床試験 Toxicant Exposures After Switching From Cigarettes to a Pod-Based Electronic Cigarette A Randomized Clinical Trial

Jessica M. Yingst, DrPH; Nicolle M. Krebs, MS; Sitasnu Dahal, DrPH, RN;et al
JAMA Network Open Published:May 19, 2026
DOI:10.1001/jamanetworkopen.2026.13292

Visual Abstract.

Key Points

Question What are the short-term effects of switching from cigarettes to a pod-based salt nicotine electronic cigarette (EC) among adults who smoke cigarettes daily?

Findings In this randomized clinical trial of 104 participants, switching from cigarettes to a 5% nicotine EC for 6 weeks was associated with reduced levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, a tobacco-specific lung carcinogen biomarker, compared with the 0% nicotine EC. The difference was not statistically significant when controlling for several key baseline variables

Meaning These findings suggest that EC nicotine delivery plays an important role in facilitating reduction in toxicant exposure from cigarettes.

Abstract

Importance Electronic cigarettes (EC) have been shown to expose users to fewer tobacco-related toxicants compared with combustible cigarettes. The current generation of ECs has rapidly shifted toward pod-based nicotine salt formulation ECs, and more research is needed to understand the impacts of using these EC products among those who smoke.

Objective To determine the short-term effects of switching from cigarettes to a pod-based 5% nicotine EC, compared with a 0% nicotine EC.

Design, Setting, and Participants This double-blind, parallel-arm, randomized, placebo-controlled trial with follow-up at 6 weeks (randomized phase) and 10 weeks (postrandomized phase) was conducted at a single-site academic medical center in Pennsylvania from April 22, 2022, to December 12, 2023. Participants included adults who smoked more than 4 cigarettes per day (CPD) and expressed interest in switching completely to an EC. Data were analyzed from August 23, 2024, to December 1, 2025.

Interventions Participants were allocated 1:1 to the standardized research EC (SREC) with 5% nicotine or 0% nicotine for 6 weeks.

Main Outcomes and Measures The primary outcome was concentration of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in urine corrected for creatinine level at 6 weeks. Secondary outcomes included exhaled carbon monoxide (CO), cotinine level, CPD, CO-verified cigarette abstinence, and levels of volatile organic compounds.

Results A total of 104 participants (52 per group) were randomized, of whom 68 (65.4%) were female, with a mean (SD) age of 50.9 (10.0) years. At 6 weeks, the 5% SREC group did not have significantly lower NNAL levels (mean difference [MD], −116.6 [95% CI, −245.4 to 12.2] pg/mg; P = .08). However, a greater proportion of participants in the 5% SREC group were abstinent from cigarettes (19 of 52 [36.5%] vs 6 of 52 [11.5%]; P = .005), compared with the 0% SREC group. The 5% SREC group had greater cotinine levels (MD, 2367.8 [95% CI, 407.5-4328.2] ng/mg; P = .02); however, there were no differences in CPD (MD, −0.9 [95% CI, −3.9 to 2.1] CPD; P = .55) or exhaled CO levels (MD, −5.1 [95% CI, −12.9 to 2.6] ppm; P = .19) between groups. Levels of cyanoethyl mercapturic acid (CYMA) (MD, −49.0 [95% CI, −90.4 to −7.6] ng/mg; P = .02) and 3-hydroxypropyl mercapturic acid (3HPMA) (MD, −290.8 [95% CI, −514.0 to −67.6] ng/mg; P = .01), biomarkers of acrylonitrile (a carcinogen) and acrolein (a cardiac toxicant) exposure (both of which are respiratory toxicants), were lower in the 5% SREC group compared with the 0% SREC group.

Conclusions and Relevance In this randomized clinical trial of adults who smoke, switching from cigarettes to a 5% SREC vs a 0% SREC resulted in reduced exposure to some toxicants delivered by cigarette smoking and an increased rate of smoking cessation. ECs that deliver nicotine like a cigarette may have an important role in reducing the harmful toxicant exposure caused by cigarette smoking.

Trial Registration ClinicalTrials.gov Identifier: NCT03625986