以下是不抽烟的另一个理由。
Smoking can permanently damage your genetic material, according to a new study.
根据一项新的研究，吸烟会永久损害你的遗传物质。
Researchers at the Hebrew SeniorLife Institute for Aging Research say smoking leaves a long-term "footprint" on a person's DNA or deoxyribonucleic acid. The researchers have ties to Harvard Medical School in the American state of Massachusetts.
希伯来高级生命老龄化研究所的研究人员表示，吸烟会在人类DNA中留下长期的印记。这些研究人员同美国马萨诸塞州哈佛医学院存在联系。
DNA is the genetic material of which all living things are formed. Health problems, like heart disease and cancer, are believed to be at least partly a result of damage to a person's DNA.
DNA是形成所有生物的遗传物质。心脏病和癌症等健康问题被认为是人类DNA损伤导致的部分结果。
The changes in the genes are a result of a natural process called "DNA methylation." It changes how the DNA works or operates, and possibly affects the body's natural defenses against disease.
基因变化是一种被称之为“DNA甲基化”的自然过程的产物。它改变了基因是如何作用的，并可能影响人体对疾病的自然抵抗能力。
Roby Joehanes is the first author of a report on the study. He said the researchers found ‘compelling evidence' that smoking has a long-lasting influence on our ‘molecular machinery.'
Roby Joehanes是这项研究中的一份报告的第一作者。他说，研究人员发现了吸烟对我们的“分子机器”存在持久影响的有力证据。
"The encouraging news is that once you stop smoking, the majority of DNA methylation signals return to never smoker levels after five years, which means your body is trying to heal itself of the harmful impacts of tobacco smoking," he said.
他说，“令人鼓舞的消息是，一旦你停止吸烟，过五年后，大部分DNA甲基化的迹象会回到不吸烟者的水平。这意味着身体在试图治愈吸烟对自身造成的不利影响。”
However, cigarette smoking can still have an influence on people's health more than 30 years after they stopped smoking, he said.
然而他表示，吸烟者在停止吸烟后仍然对健康具有30年以上的影响。
The researchers studied blood samples from 16,000 people, smokers and non-smokers alike. They found that for most, DNA damage resulting from smoking slowly disappeared five years after people quit smoking.
研究人员研究了1.6万人的血样，其中有吸烟者也有不吸烟者。他们发现，对大多数人来说，吸烟对DNA造成的损害在人们停止吸烟5年后慢慢消失。
But some of the damage appeared to be permanent.
但是有些损害似乎是永久性的。
Researchers said in the study, the smokers experienced changes to more than 7,000 genes. That is about one-third of known human genes.
研究人员表示，在这项研究中，吸烟者有7千种以上的基因发生了变化，这大约是已知人类基因的1/3。
DNA methylation is one of the ways genes are expressed, or show up, in the body. It affects which genes ‘turn on' and that can lead to the development of smoking-related diseases, said Dr. Stephanie J. London. She works at the U. S. National Institutes of Health and was another author of the study.
DNA甲基化是人体基因表达的机制之一。它会影响基因的“启动”，而这会导致患上吸烟相关的疾病，Stephanie J. London博士做出上述表示。她就职于美国国立卫生研究院，也是这项研究的另一位作者。
"Equally important is our finding that even after someone stops smoking, we still see the effects of smoking on their DNA," she said.
她说，“同样重要的是，我们发现有人即使停止吸烟，我们仍然能看到吸烟对其DNA造成的影响。”
Smoking is the leading cause of preventable health disorders. It kills an estimated 480,000 Americans every year, according to the Centers for Disease Control and Prevention.
吸烟是可预防疾病的主要原因。美国疾病控制和预防中心表示，吸烟每年估计会导致48万美国人死亡。
Smoking is believed to cause more than 6 million deaths worldwide each year, mostly through cancer, heart disease and lung disease.
据认为吸烟每年会导致全球范围内超过6百万人死亡，其中多数是通过癌症、心脏疾病和肺部疾病。
Campaigns to get people to give up smoking have seen some success in the United States. Smoking levels have dropped. Now only an estimated 15 percent of the adult population smokes.
戒烟宣传活动在美国已经取得了一些成功。吸烟水平有所下降。目前估计只有15%的成年人吸烟。
The study was published in the American Heart Association journal, Circulation: Cardiovascular Genetics.
该研究发表在美国心脏病协会的杂志《循环：心血管遗传学》上。
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