By Esther Carenza ( December 28, 2017, 8:57 AM EST) -- When a person smokes marijuana, delta-9-tetrahydrocannabinol (THC) is widely distributed to tissues, resulting in pharmacological effects. However, body fat provides a long-term storage site. A study (Acute and Residual Effects of Cannabis on Simulated Driving Performance of Young Adults, paper presented at Problems of Drug Dependence) done where people ingest THC, the peak levels of THC in the blood can vary substantially and any impairing effects on individuals may differ as well. The fact is, THC comes out of fat tissues relatively slowly, so a person who smokes many cannabis cigarettes per day for a long time and then stops using might show trace amounts in blood tests for days or possibly weeks....