Research Shows that Thirdhand Smoke Specific Compound “NNA” is Toxic to Human Lung Cells

A recent study from Lawrence Berkley National Laboratory in California investigated chemical compounds specific to thirdhand smoke pollution to study their harmful effects on human cells. They focused on the tobacco-specific compounds in thirdhand smoke that are known to cause cancer.

July 13, 2022

By Avery Crosley

Compared to chemicals in mainstream smoke and secondhand smoke, NNA [1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal] is known to be a unique compound of thirdhand smoke residue. Traces of NNA can be found in urine or blood samples from those exposed to thirdhand smoke—making it a specific measure of thirdhand smoke exposure. NNA is one of many tobacco-specific nitrosamines—a group of carcinogenic, or cancer-causing, compounds found in tobacco products. People can be exposed to NNA by touching surfaces polluted by thirdhand smoke or inhaling dust contaminated with thirdhand smoke residue.

After the scientists exposed human lung cells to NNA at various doses, they found that NNA is toxic to human DNA. The researchers discovered that when human lung cells are exposed to NNA, cellular transcription and replication are altered, leading to elevated risk of cancer. Furthermore, exposure to NNA can induce double-strand-DNA breaks, where both strands of a DNA duplex are severed. These results prove that NNA is one of the constituents of thirdhand smoke exposure that causes negative health effects.

In an interview with the lead author, Dr. Bo Hang emphasized the importance of understanding what NNA does to humans at the cellular level. He also mentioned that previous animal studies had shown similar results, and that this study demonstrated similar effects on human DNA. Dr. Hang said that it is challenging to do a study like this one because there are so many compounds in the thirdhand smoke mixture and that it is important to isolate the compound you are researching. He stressed the need for further research and an established understanding of health risks associated with thirdhand smoke exposure.

Previous studies report that THS exposure can cause genomic instability and is linked with an increased risk of cancer. The study found that when human lung cells are exposed to NNA, cellular transcription and replication are negatively affected. Cellular replication and transcription stress are linked with an elevated risk of cancer. The results conclude that NNA is toxic to genes and is linked to thirdhand smoke exposure-induced negative health effects. These outcomes are important because they add to our understanding of the negative health consequences of thirdhand smoke exposure. Cleaning up thirdhand smoke polluted spaces and comprehensive smoking bans are essential for protecting everyone, specifically infants, from the continued formation of thirdhand smoke reservoirs.

Click here to read the research study.

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