How harmful are e-cigarettes: here's what you need to know

​Using e-cigarettes is substantially less harmful to individual health than inhaling smoke from combustible tobacco such as cigarettes and cigars. But while e-cigarettes contain far fewer toxins than combustible cigarettes, they are not free of toxins and still deliver harmful chemicals.

The basic technology behind e-cigarettes is consistent but there is an enormous variability within the product category and there is no typical e-cigarette. The products have different ingredients and different hardware, and deliver highly variable amounts of nicotine and potentially toxic chemicals. This variation makes it difficult to make overall public health recommendations about e-cigarettes and is a driver for the need for regulation. Consumers need to consistently know what they are getting — particularly from a product designed to deliver chemicals by frequent inhalation.

There is substantial confusion about the health effects of e-cigarettes. A recent 2015 study found that among adult smokers, 30.8% thought e-cigarettes were about as harmful as cigarettes, 4.3% thought they were more harmful, 28.9% didn’t know and only 36% thought they were less harmful.

Among all age groups, e-cigarettes are most commonly used by those who also use other tobacco products, such as combustible cigarettes. This pattern is commonly referred to as “dual use” or “poly tobacco use.”

Among adult users, dual use is a troubling pattern because it suggests that some e-cigarette use may be supplementing smoking instead of replacing it. Because there is no safe level of smoking, there are concerns that this behavior represses efforts to completely quit smoking (i.e., people choose to “cut down” instead of quitting smoking entirely). This issue is somewhat complicated because some individuals who use e-cigarettes to quit may experience a period of dual use as they change products.

Among youth, the data are more difficult to interpret. Dual use may indicate that kids who use other nicotine products are also more likely to use e-cigarettes due to shared character traits — like sensation seeking and openness to risk (the “shared liability” theory) — and/or the fact that initial e-cigarette use is a cause of subsequent use of other nicotine products (the “gateway” theory).

A 2018 report from the National Academies of Sciences, Engineering, and Medicine addressed this issue and concluded that there is “substantial evidence that e-cigarette use increases risk of ever using combustible tobacco cigarettes among youth and young adults,” suggesting that e-cigarette use itself is a risk factor, not just a correlation with smoking.

Addiction, brain development and chemicals

Nicotine is an addictive substance, but its level of addictiveness can vary substantially depending on its mode of delivery. Nicotine delivered by tobacco combustion is the most addictive form. The rise in the popularity of e-cigarettes that can deliver levels of nicotine similar to combustible cigarettes is causing concern about the potential risk for addiction.

Exposure to nicotine among youth is particularly dangerous since it has been shown to have an effect on key brain receptors, making young people more susceptible to nicotine addiction. There is some evidence that the effect of nicotine on developing brains may result in nicotine addiction and greater vulnerability to addiction to other drugs as well.

Because many e-cigarettes contain nicotine, which can alter nerve cell functioning in developing organisms, especially during fetal development, they should not be used by youth or pregnant women.

Pregnant women who use nicotine are at a greater risk of stillbirth and preterm delivery.

While e-cigarettes contain far fewer toxins than combustible cigarettes, they are not free of toxins and still deliver harmful chemicals. At least 60 chemical compounds have been found in e-liquids, and more are present in the aerosol produced by e-cigarettes.

Exposure to aerosol from e-cigarettes may expose non-users to nicotine, but research indicates that secondhand aerosol results in substantially lower exposure to toxicants and carcinogens than secondhand cigarette smoke. However, exposure among vulnerable populations, including pregnant women and children, could still be dangerous.

Researchers have identified several substances which are either harmful or potentially harmful to e-cigarette users, including delivery solvents and propylene glycol, which can cause dry mouth and upper respiratory infections.

E-cigarette flavours — even those approved for ingestion — have not been studied for toxicity if inhaled over long periods of time. Many e-cigarette flavourings contain chemicals that are known to be respiratory irritants, and research has found that some flavours are potentially more toxic than others. For example, researchers found that exposure to increased cinnamon flavouring caused significant cell death, compared with other flavours.

Additionally, mixing multiple flavors can be more toxic to cells than exposure to just one flavor at a time. The repercussions of long-term exposure to the chemicals found in e-liquids and produced by e-cigarettes are not yet known, since products have not been on the market long enough to conclusively study their effects.

* This info is part of an article that first appeared on the Truth Initiative's website.