Study Says Menthol Vaping Products Generate More Toxic Particles That Affect Lung Function

Today’s news, April 12: According to foreign media reports, researchers at the University of Pittsburgh Respiratory Research Institute reported today that adding menthol flavoring to e-cigarettee-liquid produces more vapor particles and is associated with worsened lung function in users.

Using a specially designed robotic system to simulate human breathing and puffing behavior, the researchers showed that commercially available e-cigarette e-liquids containing menthol generate more toxic microparticles than e-liquids without menthol. A secondary analysis of patient records from a group of e-cigarette users showed that, compared with non-menthol users, menthol e-cigarette users breathed more shallowly and had poorer lung function, regardless of age, sex, race, pack-years of smoking, nicotine use, or use of cannabis-containing vaping products.

Kambez H. Benam, Ph.D., senior author of the study and associate professor in the Division of Pulmonary, Allergy and Critical Care Medicine at the University of Pittsburgh School of Medicine, said:

Many people, especially young people, mistakenly believe that e-cigarettes are safe, but even nicotine-free e-cigarette mixtures contain many compounds that may damage the lungs. Just because something is safe to eat in food does not mean it is safe to inhale.

To keep young people away from e-cigarettes and curb preventable deaths, the U.S. Food and Drug Administration continues to pressure cigarette manufacturers to eliminate menthol from combustible tobacco products such as regular cigarettes and cigars. But the global market for vaping products continues to expand, and mint and menthol flavors remained very popular among the 2.5 million young people who reported using e-cigarettes in 2022.

Because traditional toxicity testing involving animals or live cells grown on flat surfaces may take weeks or months to generate high-quality, clinically relevant data, regulators are struggling to keep up with product safety testing in a timely manner.

Traditional methods have other limitations as well. Mice and rats, the main animals used to test the safety and biological effects of aerosol products, have nasal anatomies that are very different from humans, making them unable to actively breathe through the mouth the way a person does when taking a puff. Cell systems used for toxicity testing are either directly exposed to e-liquid or subjected to continuous aerosol spraying that does not account for human breathing patterns.

To improve preclinical testing of how mixed e-cigarette liquids and added flavorings affect vapor composition and health outcomes, the researchers developed a biologically inspired e-cigarette robot. By accurately simulating temperature, humidity, puff volume, and puff duration, the machine can mimic both healthy and diseased breathing patterns and reliably predict vaping-related lung toxicity.

The system can measure the size and number of aerosol particles produced, as well as how these parameters change depending on liquid composition. The aerosol’s effects can then be tested on engineered lung-on-a-chip devices, quickly generating high-quality data that can be used to infer potential toxicity.

In their previous research, Benam and his team found that vitamin E acetate, a common additive in cannabinoid-containing e-cigarette liquids, generates more toxic small particles that can travel deep into the lungs and lodge in the narrowest airways and in the lining of the trachea and bronchi.

Although large-scale clinical studies will still be needed in the future, this new study suggests that menthol additives may be just as dangerous as vitamin E acetate, which has been closely linked to lung injury associated with e-cigarette and vaping product use.

“The main message we want to communicate is aimed at people who have never smoked before, especially young people,” Benam said. “For those trying to quit conventional tobacco products, switching to e-cigarettes may be a better and safer option. But before trying e-cigarettes, it is important to fully understand both their risks and benefits.”

Other authors of the study include Dr. Divay Chandra and Dr. Rachel Bogdanoff of the University of Pittsburgh, and Dr. Russell Bowler of National Jewish Health in Denver.