Washington, May 28: A common e-cigarette flavouring has toxic chemicals similar to those found in tobacco smoke, which disrupts the lungs' antibacterial defence system, a study has found. "Our data suggest that when used in e-cigarettes cinnamaldehyde, like toxic aldehydes in cigarette smoke, significantly disrupts normal cell physiology in ways that may have implications for the development and exacerbation of the respiratory disease," said Phillip Clapp, at the University of North Carolina in the US.
"Our finding that cinnamaldehyde impairs normal airway cilia motility is significant because it demonstrates that a common, food-safe flavouring agent, in the context of e-cigarette use, is capable of dysregulating a critical anti-bacterial defence system in the lungs," said Clapp. Cinnamaldehyde is the chemical that gives cinnamon its characteristic flavour and odour.
Researchers performed their experiment by exposing human bronchial epithelial cell (HBEC) cultures to diluted cinnamon e-liquids and e-liquid aerosols from a third generation e-cigarette device. The frequency of movement of hair-like projections (cilia) that clear mucus and dirt from the lungs - that is, cilia beat frequency (CBF) - was measured over 120 minutes using a high-speed digital camera and a video analysis system.
The cinnamaldehyde content of each e-liquid was determined, and HBECs were then exposed to various concentrations of cinnamaldehyde to determine if cilia beat frequency changed as the dose increased. The researchers evaluated changes in mitochondria oxidation phosphorylation, the process by which cells generate the majority of their cellular energy.
Several different reactive aldehydes, a group of chemicals also found in cigarette smoke, cause lung inflammation, and increase susceptibility to bacterial and viral infections. In recent years, e-cigarettes have emerged as potentially safer alternatives to traditional cigarettes because they provide the sensation of smoking and the desired nicotine effect without burning tobacco.
"E-cigarette emissions contain chemicals that have not been evaluated for inhalation toxicities," said Clapp. "The inhalation of flavouring agents, which are frequently reactive aldehydes, poses a significant unknown in regards to the potential health risks of e-cigarette use as many of these chemicals are structurally similar to toxic aldehydes in cigarette smoke," he said.
"Moreover, aldehyde flavouring agents are often used in exceedingly high concentrations in e-cigarettes, which may lead to high exposure doses," he added. Researchers decided to conduct this experiment because many food additives "generally recognised as safe (GRAS)" by the US Food and Drug Administration (FDA) have been added to e-cigarettes without further study of their effects when inhaled. They became especially concerned after looking at the chemical structures of various e-cigarette flavouring agents that have chemical structures similar to those that are found in cigarette smoke with known toxicities.