Lawrence Berkeley National Laboratory (Berkeley Lab) has discovered two additional carcinogens in e-cigarette liquids.
In their recent study published in Environmental Science & Technology, researchers examined three types of e-liquids and two types of vaporizers (one-coil and two-coil) at various battery power levels. The researchers discovered that the first puff looks very different from the last puff in terms of emissions.
One example used was the emission of acrolein, a severe eye and respiratory irritant. With the single-coil e-cigarette operating at 3.8 volts, the first five puffs emitted .46 micrograms per puff of the chemical, but the last emitted 8.7 micrograms per puff.
“When you apply the same voltage to the double-coil e-cigarette you see a lot less emissions,” said Lara Gundel, co-author and Berkeley Lab researcher. “We think it has to do with lower temperatures at each of the coil surfaces.”
Berkeley Lab researcher and the study’s corresponding author Hugo Destaillats was careful to add that the findings do not mean that e-cigarettes are safe at lower temperatures. “We found there are emissions of toxic chemicals at any temperature at which you use the device,” he said. “And the higher the temperature, the more emissions.”
The Berkeley Lab researchers also focused specific testing on the one element that is common in all e-cigarette liquids: a combination of propylene glycol and glycerin, solvents used in varying proportions.
These two ingredients are used to make theater smoke, as well, and, according to Destaillats, the two chemicals are considered safe for food. But the lungs process chemicals very differently than the stomach.
“People are not drinking the liquids — they’re vaping them,” said co-author and Berkeley Lab researcher Mohamad Sleiman. “So what counts is the vapor.”
The researchers vaporized purely the two solvents to ensure the results were only from them, and not an added source. They detected “significant levels” of 31 different harmful chemical compounds, two of which are carcinogens that had never previously been reported in e-cigarette vapor: propylene oxide and glycidol.
“Understanding how these compounds are formed is very important,” Destaillats advised. “One reason is for regulatory purposes, and the second is, if you want to manufacture a less harmful e-cigarette, you have to understand what the main sources of these carcinogens are.”
Diacetyl, its close cousin 2,3-pentanedione, and acetoin have also been found in 92 percent of e-liquids.
Diacetyl, especially, has been under scrutiny in recent years because of its link to serious lung diseases such as bronchiolitis obliterans, better known as “popcorn lung” because of the popcorn flavoring factory workers that were diagnosed with the disease. Bronchiolitis obliterans is when the smallest airways of the lungs become permanently scarred and restricted, obliterating airflow. It’s only treatable by lung transplant.