The phrase “chemical marker” describes a chemical compound that indicates the presence of a specific toxicant, pollutant, or risk. Many thirdhand smoke scientists use well-known chemicals only found in tobacco smoke, such as nicotine and NNK, as chemical markers of thirdhand smoke in dust and on surfaces. However, thirdhand smoke contains many other hazardous chemicals. William Richardot at San Diego State University led a study to find other chemicals that might serve as chemical markers of thirdhand smoke.
Richardot used a process called non-targeted analysis to discover chemicals in thirdhand smoke. Unlike targeted analysis, which is a method to measure the amount of a single “targeted” chemical in a sample, non-targeted analysis looks for every known chemical.
“You don’t know what else is there,” said Richardot about thirdhand smoke residue. “We’re trying to look at all the chemical compounds in a sample.”
Because thirdhand smoke settles in dust, Richardot used dust samples from the homes of both people who do and do not smoke.
In the laboratory, Richardot said he found “1000’s of chemicals” in the dust samples. It took him months to confirm that he identified the chemicals correctly, he said.
Of these 1000’s of chemical compounds, Richardot selected the ones that were more abundant in the homes of people who smoked. These compounds could possibly act as chemical markers of thirdhand smoke.
Richardot’s results show the importance of non-targeted analysis to discover which chemical compounds are unique to thirdhand smoke and could possibly serve as novel chemical markers. Non-targeted analysis draws attention to the many of the lesser-known hazardous compounds that are in thirdhand smoke or novel chemicals that are created as tobacco smoke ages. Such analyses also provide guidance for future research studies that can include Richardot’s identified compounds in their targeted analyses of thirdhand smoke.
Looking ahead, Richardot hopes to keep finding new chemical markers that shed light on specific health outcomes or the different properties of chemicals in thirdhand smoke.
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