Does wormwood contain a chemical that would cause a person to test
positive for THC in a urinalysis?

http://www.absinth.com/
Thujone is a toxic chemical present in wormwood and has a similar
molecular geometry with THC, the active chemical in cannabis.

http://www.seborabsinth.com/faqs/drugs_test.asp

Question: Will wormwood or thujone show up in a drugs test?
Answer: No, they will not show in a standard test.

http://www.evilavatar.com/forums/archive/index.php/t-6674.html

It is a drug and it may come up on a drug screening as THC. However,
most people don't know that THC seldom comes up in a drug screening
unless you just smoked some the day before your test. That stuff
doesn't "stay" in your system for 30 days as is the popular myth. Like
most drugs, it burns itself out of your system right away. A "casual"
pot smoker (say 1 joint a week or less) might never come up positive
on a UA.

I eat wormwood quite often. It is a natural anti-inflammatory. Looks
like there is some disagreement as to whether it shows up on drug
tests.