Cannabis smoke contains many carcinogens similar to tobacco. Tetrahydrocannabinol (THC), with the chemical name delta-9-tetrahydrocabinol, is one of the carcinogens. Preliminary epidemiological data show that long-term overexposure to THC may cause human lung cancer, with a cancer slope factor of 0.14 per mg/kg/d. On the other hand, in a lifelong (long-term) toxicological study, when feeding a group of rats (each with a bodyweight of 0.1 kg) with 0, 1, 2, 4, 8, and 16 mg of THC per day, toxicologists find that on average 3%, 3%, 20%, 53%, 85%, and 100% of all rats demonstrate chronic liver injury. Imagine you stay all day long with a frequent cannabis smoker (two joints a day) as your roommate in a rented apartment. Because of cannabis smoking, THC is found to maintain at a constant level of 0.8 mg-THC/m3-air in the indoor air. You inhale 15 m3 of air every day. You live in this rented apartment for four years. Assume you have no THC exposure before or after this period. You have a bodyweight of 60 kg
througout your life, and you can live for 70 years. Based on the lifetime average daily dose (LADD) found in Question 13, the lung cancer
a. Risk assessment
b. Environmental exposure
c. Health implications
d. Toxicological effects