Congratulations to the Graduate Students Conducting Research on Thirdhand Smoke

We at the Thirdhand Smoke Resource Center wanted to take a moment to recognize two graduate students who were mentored by Thirdhand Smoke Consortium researchers on their thesis and dissertation. The first is Fajer AlEnezi, a Master’s student from San Diego State University (SDSU) who was mentored by Christopher Harrison, PhD, a bioanalytical chemist at SDSU. The second is Henry Jay Colby VI, PhD, who earned his doctorate from Drexel University. He was mentored by Peter DeCarlo, PhD, an associate professor at Johns Hopkins University Whiting School of Engineering. Below is a snapshot of their projects.

a black graduation cap has a no smoking icon and the words "go smokefree 2024" on it. Papers fly in background

Detecting thirdhand smoke, the toxic chemical residue left behind after someone smokes, currently requires complex machines, can take weeks to complete, and is expensive. However, AlEnezi thinks there could be a faster and less expensive way to test for thirdhand smoke residue. She envisions a test that would be similar to a COVID test that you can buy at a pharmacy. The person testing for thirdhand smoke would wipe a surface, put the wipe on the stick, and wait for the test to indicate if nicotine is present. To determine if this type of test would be possible, AlEnezi first had to find the best way to detect nicotine in human DNA. She used small segments of single-stranded DNA to find which strands stuck to nicotine the most. Now that this first step has been accomplished, her research can be used to develop an accessible and accurate thirdhand smoke test stick. 

E-cigarettes are becoming increasingly popular, and scientists continue to work to better understand their impact on public health, including the chemical residue they leave behind. For his dissertation Colby studied if e-cigarettes create a chemical residue on surfaces that can off-gas into the air like conventional thirdhand smoke. He released puffs of vapor from e-cigarettes into stainless steel chambers and measured the air quality during and after releasing the vapor. He found the aerosols in the vapor stuck to the chambers, creating a residue, and some of the nicotine in the residue off-gassed back into the air. In some of the chambers, Colby added ammonium sulfate particles to see how nicotine would react. The nicotine replaced the ammonium in the particles and released it as ammonia gas into the air. This study emphasizes how chemicals in e-cigarettes can create new pollutants that have the potential to harm public health.

Read AlEnezi’s thesis here.

Read Colby’s dissertation here.

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