How does smoking alter DNA?
Deoxyribonucleic acid (DNA) is the molecular basis of heredity located in the cell nuclei. DNA is the material that makes up a person’s genes, which is necessary for the construction, organization, and function of living cells, tissues, organs, and organisms. Many of humans’ most basic traits are influenced by DNA to varying degrees, such as height, weight, types of intellectual and athletic skills, and personality traits.
Additionally, DNA can influence the susceptibility to develop certain diseases, including addiction and cancer. No heritability from DNA is one-to-one. In other words, even where DNA plays a large role in the inheritance of a particular trait, such as eye and skin color, it is never 100%. DNA essentially sets boundaries between two extremes, but where a trait ultimately falls within those boundaries, in large part will be determined by one’s environment.
Environmental influences therefore still alter any particular trait. Given that even traits that are “hardwired” into DNA can change, when we talk about the traits that are less hardwired (such as the susceptibility to developing cancer or addiction), DNA is less of an influence than environment.
The term environment requires some discussion. Most people think of environment in terms of inheritance as the immediate surroundings. These may be family, geography, community, culture, and nationality. But environment also includes physical characteristics, from microscopic changes surrounding a cell to macroscopic changes such as air and water quality, and diet. Scientists are increasingly interested in how tobacco affects the micro-environment of the cell. They want to know what causes the DNA to change (or mutate) as a result of that environmental change. It is this idea that leads scientists to study all types of diet and air and water qualities in order to understand better how they impact the body and the cells more directly.
Smoking’s impact on DNA is reciprocal. In other words, there are genetic factors that influence one’s response to tobacco and tobacco in turn influences one’s genes by altering them through genetic mutation. This impact is threefold:
1. Individuals can be genetically more susceptible to becoming addicted to tobacco.
2. Individuals can be genetically more susceptible to the various diseases tobacco causes.
3. Tobacco itself can directly alter DNA and cause the cell to mutate.
Three separate studies have identified a genetic link between the susceptibility to become addicted and increasing the likelihood of developing lung cancer by up to 80%. These genetic variations involve a region on chromosome 15, which codes for the nicotine receptors. Possessing a single copy of the mutation increases the risk of developing lung cancer by 30%.
Possessing two copies increases the risk by 80%. Several studies have concluded that smoking damages the DNA in the cells, causing carcinogenic changes that contribute to the risk of developing cancer. Over 19 primary carcinogens have been identified in tobacco smoke. .
