In season three of Friends, my favorite sitcom in the world, Rachel Green tries to help her friend Chandler Bing quit smoking, first by physically removing cigarettes from his mouth, and then by giving him a hypnosis tape. Chandler, perpetually sarcastic, balances the tape on his arm like it’s a nicotine patch and watches in disgust as it slides off and hits the ground. It’s not the first time Chandler had tried to quit smoking: in season one, Phoebe Buffay offers him $7,000 (and actually pays up) to quit, which obviously only does the trick for two years. Whether you receive a generous cash bribe, listen to hypnosis tapes, chew nicotine gum, or use nicotine patches, there are many methods that people use to try to stop smoking.
In 2004, battery-powered electronic cigarettes (e-cigarettes) hit the commercial market – the devices heat up liquid and turn it into an aerosol vapor, or e-liquid, that can be inhaled. The contents typically consist of nlycerine, propylene glycol, flavoring (like mint or menthol), and varying (or nonexistent) levels of nicotine; we’ve even seen some 3D printed vaporizers for e-cigarettes. People who are trying to kick the habit can choose to take up vaping as a less toxic alternative, as the amount of nicotine in e-cigarettes is not nearly as harmful as it is in tobacco cigarettes…or so we thought. A recently published study by chemists at the University of Connecticut (UConn) has new evidence that e-cigarettes could be just as bad for us as real cigarettes.
UConn postdoctoral chemistry researcher and lead author of the study Karteek Kadimisetty said, “From the results of our study, we can conclude that e-cigarettes have as much potential to cause DNA damage as unfiltered regular cigarettes.”
The UConn team used a low-cost, 3D printed testing device to determine that e-cigarettes with nicotine-based liquid can cause just as much DNA damage as unfiltered tobacco cigarettes, and also that the vapor from non-nicotine cigarettes is as harmful to our DNA as filtered cigarettes, perhaps because of all the chemical additives in e-cigarette vapors. The National Institute of Environmental Health Sciences, from the National Institutes for Health, provided funding for the study.
Last year, the FDA tightened e-cigarette regulations amidst growing concern about their possible health impacts, including if they act as a gateway for future tobacco smokers. Scientists at UConn wanted to test out their newly developed electro-optical screening device and see if the chemicals in e-cigarettes were harmful to human DNA. The team believes that its small 3D printed screening device is the first of its kind that quickly detects DNA damage, or genotoxicity, in environmental samples in the field. DNA damage that causes cellular mutations can lead to a cancer diagnosis, so the work the UConn team is doing is pretty important.
“Some people use e-cigarettes heavily because they think there is no harm. We wanted to see exactly what might be happening to DNA, and we had the resources in our lab to do that,” said Kadimisetty.
The 3D printed device pushes liquid samples, with the help of micropumps, across several microwells that are embedded in a small carbon chip; these microwells are pre-loaded with reactive human metabolic enzymes and DNA. New metabolites that can cause DNA damage form as the samples fall into the microwells, and any reaction between the DNA and the metabolites generates light, which is captured by a camera. The scientists can tell within five minutes how much relative DNA damage is produced by a liquid sample by how intense this light in the microwell is. What’s really interesting about this 3D printed screening device is that during the testing, it converts chemicals into their metabolites, mimicking what actually happens in our bodies.
The UConn array offers an extremely fast-acting initial genotoxicity screening tool, and the essential carbon chip is disposable, and, thanks to recent advances in 3D printing technology, costs only one dollar to fabricate.
UConn chemistry professor James Rusling, the senior researcher on the study, said, “What we developed is very cheap to make, efficient, and can be used by almost anyone.”
Rusling’s lab specializes in developing efficient and affordable labs on a chip, and he explains that similar arrays could have the capacity to offer quick genotoxic screening for monitoring or testing fresh water supplies, during drug development, and even early detection of aggressive cancers.
The UConn research team extracted smoke from tobacco cigarettes and used an artificial inhalation technique to get vapor samples from e-cigarettes. The cigarettes were connected to a tube with a cotton plug, and a syringe at the other end replicated inhalation; the cotton captured the samples. They set the test at a research-supported ratio: 20 puffs of an e-cigarette roughly equaled smoking one tobacco cigarette. Samples were gathered at 20, 60, and 100 puffs, and instead of testing the hundreds of potentially harmful chemicals in e-cigarettes, the team targeted three carcinogenic chemicals found in tobacco cigarettes. The 3D printed device’s microwells were loaded with enzymes that would convert these chemicals into metabolites, and the test gave a genotoxicity reading only if the chemicals were found in the sample.
Kadimisetty was surprised by the results, which showed that the potential DNA damage from e-cigarettes increased with the number of puffs.
“I never expected the DNA damage from e-cigarettes to be equal to tobacco cigarettes. I was shocked the first time I saw the result, so I ran the controls again. I even diluted the samples,” Kadimisetty said. “But the trend was still there – something in the e-cigarettes was definitely causing damage to the DNA.”
The findings of the study, titled “Automated 3-D Printed Arrays to Evaluate Genotoxic Chemistry: E-Cigarettes and Water Samples,” were published in the ACS Sensors journal; co-authors include Kadimisetty, Rusling, and Spundana Malla, a scientist at Alliance Pharma and a former UConn PhD student. Kadimisetty explains that how much DNA damage e-cigarettes can cause depends on several factors, like the other additives present in the e-cigarette, how much vapor a person inhales, and whether nicotine or non-nicotine liquid is used.
However, not everyone agrees with UConn’s methodology: the National Health Service (NHS) in the UK, citing its Smokefree campaign, still says that e-cigarettes are better for smokers than tobacco cigarettes, since they don’t produce carbon monoxide or tar.
A spokesman for the United Kingdom Vaping Industry Association told Metro, “The public health research in the UK is very clear. Public Health England have found vaping is likely to be 95% less harmful than smoking. The Royal College of Physicians found that vaping did not exceed 5% of the harm from smoking. Earlier this year, Cancer Research UK stated that not only is vaping a safer alternative to tobacco, it’s long term harmful effects appear to be minimal. Though this study certainly warrants further research, the University [of Connecticut] admits that the device they used to measure toxicity is new and not as comprehensive as current techniques of measurement.”
Whether you agree with UConn or the UK Vaping Industry Association, maybe you shouldn’t throw out that nicotine gum just yet.
[Sources: UConn Today, Metro]