Is Vaping with Additives Safe?

By Maria Herrera
October 10, 2016

Little has revolutionized the cannabis industry in the past few years more profoundly than the vape pen, but questions are surfacing about whether additives and compounds commonly found in vape oils pose health hazards to humans.

Vape oils often contain many seemingly-benign compounds—such as propylene glycol, polyethylene glycol (PEG), and vegetable glycerin—which are commonly used as carriers of flavors in cannabis concentrates, and to make the oils thinner and easier to vape. In some cases, the compound’s own sweet taste makes them perfect companions to cannabis extracts. Until now, however, most safety testing has assumed that the substances would be consumed, not inhaled. In assessing related potential risks, scientists evaluate what happens to these compounds when they are combusted (i.e.vaped), taking into account factors such as number of puffs, puff volume, duration and, importantly, temperature.

New research from Lawrence Berkeley National Laboratory (Berkeley Lab) published in July traced the source of harmful chemicals in many e-cigarettes to propylene glycol and glycerin. Published in Environmental Science & Technology, the study found that the thermal decomposition of these substances found in many vape pens and e-cigarettes, leads to emissions of as many as 31 harmful toxic chemicals, including acrolein and formaldehyde.

Propylene glycol—according to the Agency for Toxic Substances and Disease Registry—is used to maintain moisture in medicines, cosmetics, and food products. It’s also a solvent for food colors and flavors, and used in the paint and plastics industries. It is the stuff at concerts and theatrical production that makes up artificial smoke.

Dr. Jahan Marcu, author of “The Hidden Dangers of Propylene Glycol,” which appeared in Project CBD’s website, questions the safety of these compounds. As Chief Scientist for Americans for Safe Access—a membership-based organization working to ensure safe and legal access to cannabis for therapeutic uses and research—Dr. Marcu has stated that a thermal breakdown product of propylene glycol is formaldehyde, which is considered a “Group 1 carcinogen” (carcinogenic to humans) by the International Agency for Research on Cancer.

Among some of the other important findings in the study is the fact that not all puffs are created equal: Emissions of formaldehyde, acetaldehyde, and acrolein—all either carcinogens or respiratory irritants—increased with usage as buildup collects around the heating element of a vape pen.

Another additive commonly found in vape oils is polyethylene glycol (PEG). Composed of repeating ethylene glycol molecules, PEG is a chemical compound widely used in cosmetics such as moisturizer creams, laxatives and toothpaste as thickeners, solvents, and softeners.

The Toxic Free Foundation—a database of compounds such as polyethylene—reports that impurities have been systematically found in various PEG compound. These impurities include ethylene oxide; 1,4-dioxane; polycyclic aromatic compounds; and heavy metals such as lead, iron, cobalt, nickel, cadmium, and arsenic – many of which are linked to cancer. Ethylene oxide, for example, is highly toxic even in small doses, and was used as a component in World War I nerve gas.

While the Food and Drug Administration (FDA) has designated propylene glycol as “generally recognized as safe” (GRAS) for use in food, the FDA designation assumed that the compound would be eaten, not inhaled. It might also be worth noting that other FDA ‘GRAS’ substances have been found to cause illnesses and even deaths, including artificial coloring Red #3. Banned from cosmetics in 1990 after studies found it caused cancer in animals, it can still been found in foods such as chewing gum, popsicles and yogurts).

Patient advocates such as Dr. Marcu would like to see proper labeling of vape pens listing any ingredients that may have been added to the cannabis extract, as well as an explanation about how to correctly used them, such as what temperature to store the oils and how long to hold the vape button.

One manufacturer is proactively addressing the issue of additives. Temple Extracts, a California-based vape producer, uses pesticide-free, organically-grown cannabis, and processes their cannabis oils without PEG, propylene glycol or other additives. “We feel very strongly that creating pure oils should be the standard, not the exception,” according to Michael Straus, one of Temple’s principal consultants, and a long-time organic foods / sustainable agriculture expert.

“Not all vape pens are cut with these agents,” Marcu added in a phone interview. “There are tons of products (in the general marketplace) that are safe, and we should be able to do the same with cannabis.”

Ultimately, it falls upon the consumer to ask the right questions, and to seek products that are manufactured with integrity and get as close to pure as possible.


Maria Herrera is a freelance journalist and the Communications Director at the Nevada County Cannabis Alliance. She can be reached at
References: (1) Correlation of volatile carbonyl yields emitted by e-cigarettes with the temperature of the heating coil and the perceived sensorial quality of the generated vapours. Int J Hyg Environ Health. 2016 May;219(3):268-77. doi: 10.1016/j.ijheh.2016.01.004. Epub 2016 Jan 25. Author information 1European Commission, Joint Research Centre, Institute for Health and Consumer Protection, 21027 Ispra, VA, Italy. Electronic address: 2European Commission, Joint Research Centre, Institute for Health and Consumer Protection, 21027 Ispra, VA, Italy. (2) Emissions from Electronic Cigarettes: Key Parameters Affecting the Release of Harmful Chemicals Mohamad Sleiman†‡§, Jennifer M. Logue†, V. Nahuel Montesinos∥, Marion L. Russell†, Marta I. Litter∥⊥, Lara A. Gundel†, and Hugo Destaillats*† † Indoor Environment Group, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS70-108B, Berkeley, California 94720, United States ‡ Institut de Chimie de Clermont-Ferrand (ICCF), Université Clermont Auvergne, Sigma-Clermont, BP 10448, F-63000 Clermont-Ferrand, France ICCF, UMR 6296, CNRS, F-63178 Aubière, France ∥ División Química de la Remediación Ambiental, CNEA-CONICET, Avenida Gral. Paz, (1650) San Martín, Buenos Aires, Argentina ⊥ Instituto de Investigación e Ingeniería Ambiental, Universidad de General San Martín, Campus Miguelete, Av. 25 de Mayo y Francia, (1650) San Martín, Buenos Aires, Argentina Environ. Sci. Technol., Article ASAP, DOI: 10.1021/acs.est.6b01741, Publication Date (Web): July 27, 2016 Copyright © 2016 American Chemical Society (3) (4)