I think twoguysupnorth has it nailed, it is a myth that you have to heat THC to "activate" it for injestion or absortion. I have tried every immaginable way to work with cannabinoids and all that heat ever seems to do (with the exception of carrying out cannabinoid conversions) is breakdown some of the tetrahydrocannabidols into its lower forms; one example is the promotion of oxidation of THC causing the formation of cannabinol.

As far as the Hemp T-shirt goes, and failing a urine test I have an exceptionally difficult time believing that is actually true.

Drug tests not only test for Delta 9 THC, but they are also designed to test for base cannabinoids which even though those substances are found in great quantities in hemp vs. THC (although considerably lower than regular cannabis) I still doubt the validity of that arguement, there simply isn't enough material in the shirt to transfer to your body,

Even if you managed to absorb every bit of the cannabinoids from your shirt Hemp at best in it's raw unadulerated and unprocessed form contains an average of about 4.53 grams of raw extract per pound of hemp, processed Hemp, like you shirt for example contains MUCH less. Then as it gets washed in a soapy warm water solution over the years the cannabinoid content would go close to zero.

Also absorbtion through the skin is highly ineffective. It takes extremely large quantities of Exceptional oil quality to produce even mild effects. Long story short, I don't see it happening.

At the same time, YES you can test positive from absorbtion through the skin from sloppy extractions, or in my case actually making lotions that are designed to absorb readily into your skin, but it takes A LOT.

Hope this helps.