E-cig evidence mounts

A new study has found no evidence that vapor from a commercially-available electronic cigarette promotes the development of cancer in laboratory cells, whereas smoke from a reference tobacco cigarette was found to be positive for cancer-promoting activity, even at very low concentrations.

“These results add to growing weight of evidence that e-cigarettes are likely to be significantly safer than conventional cigarettes,” said Damian Breheny, lead author and adverse outcome pathway manager at British American Tobacco.

Scientists at BAT used a test called the Bhas 42 assay to compare tobacco and nicotine products. The Bhas 42 cell transformation assay assesses the carcinogenic potential of chemicals by looking for changes in a line of cells that are characteristic of tumor development.

Bhas 42 was used to compare the tumor promoter activity of vapor from a Vype ePen, one of BAT’s commercially available electronic cigarettes, and smoke from a reference cigarette (3R4F), by exposing cells to the total particulate matter collected from the vapor or smoke.

Results showed that cigarette smoke was positive for cancer-promoting activity at concentrations as low as 6μg/mL, whereas the test electronic cigarette vapor was not observed to have any in vitro cancer promoter activity at concentrations up to 120μg/mL.

The Bhas 42 assay is part of a suite of in vitro tests being developed by BAT to compare the relative biological effects of electronic cigarettes and tobacco-heating products with those of traditional cigarettes.

“This is the first study to use the Bhas assay to compare tobacco and nicotine products, and it demonstrates the potential for its future application as part of a product assessment framework,” said Breheny.

Assessment of tobacco and nicotine products has traditionally involved genotoxicity tests, which evaluate initial DNA damage that can lead to cancer. Such tests indicate that electronic cigarette vapor, in contrast to cigarette smoke, does not cause mutations and DNA damage. Using the Bhas 42 assay allows for increased understanding of potential carcinogenic risk.

Previous research conducted by BAT has shown that Vype ePen vapor contains about 95 percent less toxicants – in terms of the nine harmful components the World Health Organization recommends should be reduced in cigarette smoke (Chem. Res. Toxicol, DOI: 10.1021/acs.chemrestox.6b00188) – than does cigarette smoke from a reference cigarette.