Is E-Liquid Safe?

The rise in popularity of e-cigarettes is happening concurrently with the boom in medical and recreational marijuana, and it isn’t without some spillovers from one into the other. Without delving into the complexities of the emerging vapor pen industry, there’s a good deal of misinformation going on about one particular facet of the portable vaporizer industry: What is in the e-liquid? Is it safe to vaporize?

Many people can already answer at least part of that question. Dispensaries have been selling their supercritical-CO₂-extracted oil mixed with glycerin (also known as glycerol, vegetable glycerin or VG) in syringes for use in vape pens for some time now. Glycerin makes cannabis oil less viscous so it flows neatly out of the syringe. The syringe, in turn, makes the oil easier to administer right into a wick-and-coil atomizer (with the exposed coil normally used for dabs) or even for e-liquid atomizers (the ones with the bar in the middle). You can tell when dabs have been mixed with glycerin if they taste sweet; glycerin is known as a sugar alcohol because of this property.

If you’re going to consume anything out of a vape pen, make sure the e-liquid is made with ingredients regulated by the U.S. Pharmacopeia Convention (USP), which describes itself as “a scientific nonprofit organization that sets standards for the identity, strength, quality, and purity of medicines, food ingredients, and dietary supplements manufactured, distributed and consumed worldwide.”

E-liquid for nicotine vaporizers often contains propylene glycol or PG, which is generally recognized as safe by the CDC. PG only becomes toxic at large doses, which is almost impossible to achieve from vaping alone. It’s used in many pharmaceutical products and some drink and foods, as well as in non-toxic antifreeze for boats and RV’s. Some countries in Europe pulled Fireball Whisky off the shelves because of its level of propylene glycol, but the FDA’s limit for PG in America is higher.

Polyethylene glycol (PEG) has somewhat fallen into disuse for nicotine e-liquids over claims about its safety. Some medicines and many household products contain PEG, and it’s regulated by the FDA.

Some e-liquid mixtures contain ethylene glycol (EG). While quite similar in structure to PG, it breaks down into toxic by-products when metabolized in the body. Normal antifreeze contains EG and is a hazardous substance that should not be ingested.

USP grade glycerin, PG and PEG can be purchased at pharmacies or online easily. Lower quality products are not meant for consumption because non-pharmaceutical grade PG and PEG can contain small amounts of the toxic ethylene glycol. The FDA has regulated these ingredients for oral and topical use, but what about inhaling vapors and possible combustion products?

A study done by researchers from Poland and New York published in April 2014 set out to answer just that question. They “measured in vapors from 10 commercially available nicotine solutions” and found that PG produced more toxic by-products, called carbonyl compounds, than glycerin. Lower voltage also produced a cleaner vapor. PEG based e-liquids decomposed the least, and the authors suggested PEG might be the safest option.

So is e-liquid safe? For the most part, just make sure it’s made with USP ingredients with no ethylene glycol.