電子たばこで肺病発症率が１．３倍に、紙巻きたばこは２．６倍

【ワシントンＡＦＰ＝時事】電子たばこの使用により、ぜんそく、気管支炎、肺気腫、慢性閉塞性肺疾患（COPD）などの慢性肺疾患発症リスクが著しく増加するとの研究結果が16日、医学誌「アメリカンジャーナル・オブ・プリベンティブ・メディシン」に発表された。ただ、発症率でみると、電子たばこは紙巻きたばこよりも害が少ないことも分かったという。（写真は資料写真）
　米カリフォルニア大学サンフランシスコ校（ＵＣＳＦ）の研究チームは、電子たばこと紙巻きたばこの利用と、２０１３～１６年の米成人３万２０００人以上の肺疾患に関する公開データを調べた。
　この結果、電子たばこの利用者および過去に利用経験がある人は、一度もたばこを吸ったことがない人に比べ慢性肺疾患の発症率が１．３倍だったことが分かった。一方、紙巻きたばこの喫煙者の発症率は２．６倍、電子たばこと紙巻きたばこの両方を利用している人の発症率は３倍だった。
　論文の主執筆者であるＵＣＳＦのスタントン・グランツ教授（医学）は「電子たばこはそれ自体が有害であり、従来のたばことは異なる影響がある」と説明した。
　今回の論文では、電子たばこによる害に対する生物学的説明はされていない。生物学的説明については、電子たばこが免疫系を抑制し、肺内のストレス関連タンパク質濃度を上昇させることを動物と人間の実験で明らかにした過去の研究を引用している。
　電子たばこを推奨する人々は、電子たばこは紙巻きたばこに比べ害が少ないため喫煙者にとって代替物となると主張している。だが、グランツ氏によると、調査の参加者の大半は紙巻きたばこと電子たばこの両方を利用していたという。
　「紙巻きたばこから電子たばこへ切り替えることで肺病リスクを減少させることが可能だが、実行する人はほとんどいない」とグランツ氏は指摘する。「大半の人は、紙巻きたばこに加え電子たばこも吸うようになる。これにより、肺病発症リスクが著しく増加する」 【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2019/12/18-10:07）

E-cigarette use significantly increases the risk of developing chronic lung diseases like asthma, bronchitis, emphysema and chronic obstructive pulmonary disease, according to a long term study published Monday that also found vaping was less harmful than smoking.
The results of the research, published in the American Journal of Preventive Medicine, are unrelated to the recent outbreak of an acute lung disease that has killed more than 50 people and has been linked to a substance commonly added to vaping products containing THC, the psychoactive component of cannabis.
Scientists at UC San Francisco examined publicly available data that tracked e-cigarette and tobacco habits as well as new lung disease diagnoses in over 32,000 American adults from 2013 to 2016.
They found that current and former e-cigarette users were 1.3 times more likely to develop chronic lung disease, while tobacco smokers increased their risk by a factor of 2.6.
For people who both smoked and vaped, the risks of developing lung disease more than tripled.
What we found is that for e-cigarette users, the odds of developing lung disease increased by about a third, even after controlling for their tobacco use and their clinical and demographic information, said senior author Stanton Glantz, a UCSF professor of medicine.
We concluded that e-cigarettes are harmful on their own, and the effects are independent of smoking conventional tobacco, he added.
The paper did not offer a new biological explanation for how vaping causes such harm, but cited earlier physiological studies in both animals and humans that have found that e-cigarettes suppress the immune system and increase the levels of stress-related proteins in the lung.
- Dual users -
There have been several earlier population studies that found an association between e-cigarette use and lung disease at a single point in time, but it was impossible to determine whether the illnesses were caused by e-cigarettes or if people with lung disease were more likely to vape.
The authors of the new study wrote that by starting with people who had no prior history of lung disease and then taking account of their use of e-cigarettes and smoking, they could identify a stronger causal link.
Vaping advocates contend that e-cigarettes offer people addicted to smoking a less harmful alternative, but according to Gantz, most of the participants in the nationally representative sample both smoked and vaped.
Switching from conventional cigarettes to e-cigarettes exclusively could reduce the risk of lung disease, but very few people do it, he said. For most smokers, they simply add e-cigarettes and become dual users, significantly increasing their risk of developing lung disease above just smoking.