Third-Hand Smoke: Old Smoke, New Concerns.

While the effects of active smoking and second-hand smoke (SHS) are well documented, the concept of third-hand smoke (THS) is a relatively new phenomenon in the environmental and public health field. This notion was coined in 2009 (Winickoff et al. in Pediatrics 123(1):e74-e79, 2009) but was not really brought to light until the New York Times published an article on the topic (Rabin in A new cigarette hazard: 'third-hand smoke'. The New York Times, http://www.nytimes.com/2009/01/03/health/research/03smoke.html?_r=0 , 2009). Research on THS is fairly new and currently only limited animal studies have been performed that explore the health impacts associated with an individual THS-specific component. The public at large has a limited understanding of this new concept. As such, attitudes and beliefs surrounding THS exposure are still immature. Future research must be conducted to facilitate hazard identification, exposure and risk assessment to address its health impact on susceptible populations and to differentiate THS versus active smoking and SHS. In addition, policies and laws concerning tobacco smoke will need to be reviewed, possibly revised with the role of THS considered as an indispensable component of a broader tobacco control strategy.