May 19 2014
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Why Thirdhand Smoke Looks to Be a First-Rate Problem

Data on thirdhand smoke—tobacco smoke left on surfaces, walls and floors—was first published in 2009. The data has raised significant concerns that the smoke can linger for months or longer, as well as combine with indoor air compounds to possibly form new carcinogens. In the last few months researchers from the California Thirdhand Smoke Consortium, funded by the University of California’s Tobacco-Related Disease Research Program (TDRP), have been presenting and publishing data that indicates that thirdhand smoke is linked to serious health risks in animals and humans—though more research is needed to better measure thirdhand smoke constituents and their health impact.

Consortium researchers published the first animal study on thirdhand smoke in January in the journal PLOS One, finding that mice exposed to thirdhand smoke developed a range of medical conditions, including liver damage and hyperactivity. Research published last year, as well as presented at the annual meeting of the American Chemical Society a few weeks ago, finds that thirdhand smoke likely causes damage to human DNA.

And last month several of the Consortium scholars presented their findings at a tobacco conference n California.

“The potential health risks of what we call thirdhand smoke are only now being studied. This is a new frontier,” said Georg Matt, a Consortium member and psychology professor of at San Diego State University who focuses on policies to protect nonsmokers. “We don’t yet know the degree of risk, but we are already finding that indoor smoking leaves a nearly indelible imprint. We need to find out what risk this pollution poses.”

Neil Benowitz, PhD, the consortium’s principal investigator, as well as the vice chair of the University of California San Francisco’s (UCSF) Department of Biopharmaceutical Sciences and co-leader of the Center for Tobacco Control Research and Education at UCSF, said risks to infants and toddlers are of particular concern because young children crawl on rugs and carpets and often put their hands in their mouths. They are also more likely than adults to have contact with pollutants that cling to surfaces in the home.

“An infant’s developing brain is very susceptible to low levels of toxins, and immature immune systems are particularly vulnerable to persistent pollutants,” said Benowitz. The Consortium researchers also worry that children and adults with respiratory diseases such as asthma are at high risk from thirdhand smoke.

“Tackling thirdhand smoke is tough because it’s pushing the technological sensitivity of measurements of pollutants,” he said Benowitz. Consortium researchers—who have been invited to apply for an additional three years of funding from the TDRP—are looking at the issue from many angles, including developing biomarkers to measure levels of pollutants, assess their persistence in the indoor environment and determine how much they are absorbed by the body.

"The effort requires many skills, like environmental chemistry, toxicology, pharmacology and the ability to track and measure the pollutants over time,” said Benowitz.

Manuela Martins-Green, a professor of cell biology at UCSF and the lead researcher of the animal study on thirdhand smoke effects, said the findings of damage to organs and other health consequences “provides a basis for studies on the toxic effects of third-hand smoke in humans and may be able to inform potential regulatory policies aimed at preventing involuntary exposure to thirdhand smoke.”

Benowitz said the Consortium is also looking at how to educate the public about potential concerns. “We hope to study remediation and create a document that tells people how to clean up a house where someone has smoked,” as well as help develop policy statements for issues such as dealing with multi-family housing where tenants are often exposed to the smoke of others.    

Next up, the Consortium will be looking at casinos to help create measurements techniques for the impact of thirdhand smoke.

Tags: Pediatrics, Research, Tobacco, Tobacco Control