Thirdhand Smoke

The toxicity and public health devastation caused by both directly smoking cigarettes and inhaling secondhand tobacco smoke are well established and generally accepted.  The role of thirdhand smoke is currently under study and its harmful role to our health is just coming into focus.

Definitions:

• Firsthand Smoke = Directly inhaling smoke while smoking a cigarette, cigar, etc.
• Secondhand Smoke = Not smoking but inhaling the smoke left by others who are currently present or have recently been smoking at your current location.
• Thirdhand Smoke = The result of residual nicotine and other chemicals left on indoor surfaces by tobacco smoke.  This residue reacts with common indoor pollutants to create a toxic mix including cancer-causing compounds.  It is gradually released back into the air as a gas or travels in the air on dust particles.

You cannot see thirdhand smoke.  The visible smoke disappeared a long time ago.   However, you certainly can smell it.  For example, if you travel in a car whose regular driver smokes, not only do you smell it in the car, but the thirdhand smoke gets on you and people can smell it on you even after you leave the car.

On one hand, you may think that if there is so little of it you can’t even see it, how can it be harmful (besides stinking)?  The factor that magnifies its toxicity is the duration of exposure.  Exposure to secondhand smoke may occur over a course of hours, but thirdhand smoke exposure could last for years if it affects your house or workplace.

Evidence so far has shown thirdhand smoke:

• causes significant DNA damage in human cell lines
• causes oxidative based lesions has been confirmed in skin wounds of mice models
• causes metabolomic changes in human reproductive cell lines
• negatively impacts body weight in both male and female mice
• induces persistent changes to immunological parameters in peripheral blood in mice
• is genotoxic at realistic experimental doses
• may cause some other forms of cellular damage

Thirdhand Smoke: New Evidence, Challenges, and Future Directions

Adverse Health Effects of Thirdhand Smoke: From Cell to Animal Models

Arnold Solof, MD