Found this researching Terpenes...
https://pubs.acs.org/doi/pdf/10.1021/acsomega.7b01130
methacrolein: https://en.wikipedia.org/wiki/Methacrolein
https://en.wikipedia.org/wiki/Benzene
https://pubs.acs.org/doi/pdf/10.1021/acsomega.7b01130
■ CONCLUSIONS
Given the widespread legalization of cannabis in the United States, it is imperative to study the full toxicology of its consumption to guide future policy. The results of these studies clearly indicate that dabbing, although considered a form of vaporization, may in fact deliver significant amounts of toxic degradation products. The difficulty users find in controlling the nail temperature put users at risk of exposing themselves to not only methacrolein but also benzene. Additionally, the heavy focus on terpenes as additives seen as of late in the cannabis industry is of great concern due to the oxidative liability of these compounds when heated. This research also has significant implications for flavored e-cigarette products due to the extensive use of terpenes as flavorings. Future research
will also be directed toward assessing the contribution of terpenoids to the existing toxicant formation in e-cigarettes. Additionally, the methods discussed herein will also be used to further study the degradation of cannabis extracts used in dabbing and cannabis e-cigarettes.
methacrolein: https://en.wikipedia.org/wiki/Methacrolein
Exposure to methacrolein is highly irritating to the eyes, nose, throat and lungs.
https://en.wikipedia.org/wiki/Benzene
OSHA regulates levels of benzene in the workplace.[68] The maximum allowable amount of benzene in workroom air during an 8-hour workday, 40-hour workweek is 1 ppm. As benzene can cause cancer, NIOSH recommends that all workers wear special breathing equipment when they are likely to be exposed to benzene at levels exceeding the recommended (8-hour) exposure limit of 0.1 ppm.[69]