Burns D M
Department of Medicine, University of California, San Diego Medical Center.
Clin Chest Med. 1991 Dec;12(4):631-42.
Tobacco use was widespread in the New World by the time of the first voyage of Columbus; however, it is only in the last century that the use of tobacco as cigarettes has been prevalent. The milder tobacco and more acidic smoke of cigarettes lead to the deeper inhalation of tobacco into the lung with resultant deposition and absorption of the addicting, toxic, and carcinogenic components of the smoke. More than 4000 individual constituents have been identified in cigarette smoke, and the relative concentrations of these constituents vary widely between brands of cigarettes. Tar yield, a measure of the total particulate matter of the smoke, varies markedly with the characteristics of the cigarette manufacture and with the pattern of inhalation. As a result, tar is not a good measure of the dose of toxic or carcinogenic agents received by the individual smoker. The particle size of cigarette smoke is in the range that will lead to deposition in the airways and alveoli of the lung, and many of the gas-phase constituents are absorbed across the alveolar capillary membrane. The irritant agents in the smoke cause acute and chronic changes in lung structure and function that may result in greater retention of carcinogens within the lung and increased vulnerability of the lung to the effects of these carcinogens. Carcinogens and other constituents of cigarette smoke are also absorbed into the blood and metabolized to active forms through microsomal enzyme systems induced by cigarette smoke. The cellular influx of neutrophils and alveolar macrophages that is part of the inflammatory response may be the precursor of the alveolar wall destruction that results in emphysema. The prevalence of smoking is not uniformly distributed across the population. Men began smoking in large numbers very early in the century, but women began to smoke in large number only at the time of the Second World War. Men born after 1930 have been less likely to take up smoking than their older counterparts. The prevalence of smoking is currently declining in both men and women.
在哥伦布首次航行到新大陆时，烟草的使用就已在那里广泛传播；然而，直到上个世纪，香烟形式的烟草使用才开始盛行。香烟中烟草较温和且烟雾更具酸性，这导致烟草更深入地吸入肺部，从而使烟雾中令人上瘾、有毒和致癌的成分得以沉积和吸收。在香烟烟雾中已鉴定出4000多种单独成分，而且这些成分的相对浓度在不同品牌香烟之间差异很大。焦油产量是烟雾中总颗粒物的一种衡量指标，它会因香烟制造的特点以及吸入方式而有显著变化。因此，焦油并非衡量个体吸烟者所接触到的有毒或致癌物质剂量的良好指标。香烟烟雾的颗粒大小处于会导致在肺部气道和肺泡中沉积的范围，并且许多气相成分会通过肺泡毛细血管膜被吸收。烟雾中的刺激性物质会引起肺部结构和功能的急性和慢性变化，这可能导致肺部内致癌物的滞留增加以及肺部对这些致癌物影响的易感性增强。香烟烟雾中的致癌物和其他成分也会被吸收进入血液，并通过香烟烟雾诱导的微粒体酶系统代谢为活性形式。作为炎症反应一部分的中性粒细胞和肺泡巨噬细胞的细胞内流可能是导致肺气肿的肺泡壁破坏的先兆。吸烟的流行在人群中分布并不均匀。男性在本世纪初就开始大量吸烟，但女性直到第二次世界大战时才开始大量吸烟。1930年以后出生的男性比他们的年长者吸烟的可能性更小。目前，男性和女性的吸烟率都在下降。
