Scientists have discovered that so-called thirdhand smoke – the residue that clings to surfaces after tobacco was smoked in the space – causes genetic damage in human cells, according to a study published in the journal Mutagenesis.

Humans can be exposed to thirdhand smoke through inhalation, ingestion or skin contact.

“Tobacco-specific nitrosamines – chemical compounds in thirdhand smoke – are among the most potent carcinogens there are,” said the study co-author, Lara Gundel, a scientist from Lawrence Berkeley National Laboratory in the United States. “They stay on surfaces, and when those surfaces are clothing or carpets, the danger to children is especially serious.”

Thirdhand smoke is particularly insidious because it is extremely difficult to eradicate. Studies have found that it can still be detected in dust and surfaces more than two months after someone smoked in an area. Common cleaning methods such as vacuuming, wiping and ventilation are not effective in lowering nicotine contamination.

Using two common in vitro tests, the researchers found that thirdhand smoke can cause both DNA strand breaks and oxidative DNA damage, which can lead to gene mutation.

Genotoxicity describes the property of chemical agents that damages the genetic information within a cell, causing mutations. It is associated with the development of diseases and is a critical mechanism responsible for many types of cancer caused by smoking and secondhand smoke exposure.

The new study also suggests that thirdhand smoke could become more harmful over time.

To generate the samples, the researchers put paper strips in two smoking chambers: acute samples were exposed to five cigarettes smoked in about 20 minutes, and chronic samples were exposed to cigarette smoke for 258 hours over 196 days.

The researchers exposed the human cells by first extracting the compounds from the paper with a culture medium then using the medium to culture the human cells for 24 hours. The concentrations of the compounds were then measured.

The researchers found that the concentrations of more than half of the compounds studied were higher in the chronic samples than in the acute samples. They also found higher levels of DNA damage caused by the chronic samples.

“The cumulative effect of thirdhand smoke is quite significant,” Gundel said. “The findings suggest the materials could be getting more toxic with time.”

“Ultimately, knowledge of the mechanisms by which thirdhand smoke exposure increases the chance of disease development in exposed individuals should lead to new strategies for prevention,” the researchers conclude.

Source: Environment News Services