Scientists have figured out how much a pack of cigarettes a day affects your DNA

Cancer sticks.
Cancer sticks.
Image: Reuters/Aly Song
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The dangers of smoking tobacco are undeniable—it kills more than 480,000 in the US alone each year. Scientists have known for a while that smoking tobacco causes significant damage to the body; as well as causing or worsening respiratory and cardiovascular issues, smoking can trigger genetic mutations that can result in cancer. But the detailed mechanisms on how smoking wreaks damage on the body’s DNA have remained somewhat elusive.

There’s finally some clarity in a new study, which provides a comprehensive picture on the devastating impact of smoking. People who smoke a pack a day (20 cigarettes) for a year develop the following mutations every year:

  • 150 extra mutations in each lung cell
  • 97 in each larynx cell (voice box)
  • 23 in each mouth cell
  • 18 in each bladder cell
  • six in each liver cell.

Each mutation doesn’t necessarily pose an immediate danger (most mutations are relatively harmless). But the more mutations there are, the higher the risk that accumulating mutations occur in key genes that turn cells cancerous.

“You can really think of it as playing Russian roulette,” Ludmil Alexandrov, lead researcher and biologist at Los Alamos National Lab in New Mexico told the Guardian. “You can miss the right genes. But if you smoke you still play the game. It’s a very strong message for people not to start smoking. If you smoke even a little bit you’ll erode the genetic material of most of the cells in your body.”

Researchers compared 2,490 tissue samples from tobacco smokers and 1,063 from non-smokers to examine the mutational consequences of smoking. They study, detailed in the journal Science, was carried out by an international research team, including the Wellcome Trust Sanger Institute in England and the Los Alamos National Laboratory in New Mexico.

Lung cancer is the deadliest form of cancer in the US (more people die from lung cancer than any other type of cancer). It continues to be the leading cause of preventable death, causing nearly 6 million deaths per year worldwide.