Carbonyl Compounds Produced by Vaporizing Cannabis Oil Thinning Agents

J Altern Complement Med. 2017 Nov;23(11):879-884. doi: 10.1089/acm.2016.0337. Epub 2017 Mar 29.


Objective: Cannabis use has increased in the United States, particularly the use of vaporized cannabis oil, which is often mixed with thinning agents for use in vaporizing devices. E-cigarette research shows that heated thinning agents produce potentially harmful carbonyls; however, similar studies have not been conducted (1) with agents that are commonly used in the cannabis industry and (2) at temperatures that are appropriate for cannabis oil vaporization. The goal of this study was to determine whether thinning agents used in the cannabis industry produce potentially harmful carbonyls when heated to a temperature that is appropriate for cannabis oil vaporization.

Design: Four thinning agents (propylene glycol [PG], vegetable glycerin [VG], polyethylene glycol 400 [PEG 400], and medium chain triglycerides [MCT]) were heated to 230°C and the resulting vapors were tested for acetaldehyde, acrolein, and formaldehyde. Each agent was tested three times.

Setting/location: Testing was conducted in a smoking laboratory.

Outcome measures: Carbonyl levels were measured in micrograms per puff block.

Results: Analyses showed that PEG 400 produced significantly higher levels of acetaldehyde and formaldehyde than PG, MCT, and VG. Formaldehyde production was also significantly greater in PG compared with MCT and VG. Acrolein production did not differ significantly across the agents.

Conclusions: PG and PEG 400 produced high levels of acetaldehyde and formaldehyde when heated to 230°C. Formaldehyde production from PEG 400 isolate was particularly high, with one inhalation accounting for 1.12% of the daily exposure limit, nearly the same exposure as smoking one cigarette. Because PG and PEG 400 are often mixed with cannabis oil, individuals who vaporize cannabis oil products may risk exposure to harmful formaldehyde levels. Although more research is needed, consumers and policy makers should consider these potential health effects before use and when drafting cannabis-related legislation.

Keywords: cannabis oil; cannabis thinning agents; cannabis vaporization; carbonyl production.

MeSH terms

  • Aldehydes / analysis*
  • Aldehydes / chemistry*
  • Biochemical Phenomena
  • Cannabis / chemistry*
  • Electronic Nicotine Delivery Systems
  • Hot Temperature
  • Plant Oils / chemistry*
  • Polyethylene Glycols / chemistry
  • Volatilization


  • Aldehydes
  • Plant Oils
  • Polyethylene Glycols