Buyers of blue tansy beware. There are unethical suppliers out there who are selling a "Blue Tansy" oil which has significant amounts of thujone (a known neurotoxin). But this is not the worst of it, when they are caught selling this fake, compounded oil, they are trying to convince their customers that this "Blue Tansy" was mistakenly labeled and should have been labeled Tanacetum vulgare instead of Tanacetum annuum, and because its vulgare that is why it has the thujone in it. They will claim that the product is not adulterated but was simply just a case of mistake in labeling it with the wrong species, and what they are selling is the "Vulgare" type of blue tansy. What these suppliers don't realize is that they cannot make the "honest mistake" plea because, unfortunately for them, the known chemistry of these plants won't allow for such a ridiculous claim. While it is true that Tanacetum vulgare has high thujone, the oil is NEVER blue as it contains no chamazulene. Tanacetum vulgare is NEVER CALLED BLUE TANSY!! If anyone tries to sell you a blue or blue-green oil that is labeled Tanacetum vulgare just know that its going to be adulterated or a completely fake product. The only way an oil from Tanacetum vulgare is going to be blue is if something else was added to it. Common Tansy (aka Idaho Tansy) from Tanacetum vulgare does not contain chamazulene and has a light yellow color. If your chemically challenged supplier tries convince you that Tanacetum vulgare should have chamazulene in it then you may want to enlighten him with the below research articles which examine all the various chemotypes of Tanacetum vulgare, none of which contain chamazulene.