When I was experimenting at the very first, I was still figuring out how to use my e-cig at the time and got that sassafrass all over, I recall. Quite a bit leaked onto the thinner brown plastic, straw-like part that one style of cartridge has. I ended up putting that cartridge away to play with other flavors and haven't used the sassafras since as I later found out it was insoluble.
Quite sometime later, when I looked at that cartridge again, I noticed that that the thin plastic part had much thinner areas which tore very readily and seemed to be actually eaten away. Nothing like that has happened with any other cartridges. I check specifically for weakening and damage there now. I'm sure the concentration of some of what I dripped into the cartridge was too high, not helped by the fact that it didn't mix in well. I figure the effect on the cartridge part might have something to do with concentration as well as that not being the right type of flavoring to use. However, I found the mental image of it doing that to my lungs disturbing enough that I decided not to use that oil for
vaping again.