It was concluded that presence ofcannabinoids in urine or blood is not unequivocal proof of active cannabissmoking. Giardino 25 26 found THC-acid levels of up to 30-50ng/ml from passive-exposed subjects, and recommended a threshold of 65ng/ml to differentiatebetween active and passive smoking of cannabis.ticht & Kaferstein 20 estimated that the blood THC concentrationsproduced in a 70kg person smoking 15mg THC would peak at 7-8 minutes,after 30 minutes between 14-42ng/ml, and at 60 minutes between 7.5-14ng/ml.3.3 McBay 21 compared THC and THC-COOH levels in a study involving smokedmarijuana cigarettes.
Calculation Using An ovulation Calendar: 1  The first day of a period is considered as day 1. 2  Usually on day 14, the egg is released and is waiting for the sperm to fertilize it. 3  The egg has a lifespan of just 12 to 24 hours whereas a sperm can last for about 72 hours in a woman.
Women who have regular periods can easily calculate when ovulation occurs. Ovulation almost always happens 14 days before you expect your period. For a woman who has 28 day cycles, that would be in the exact middle of the cycle, 14 days after the last period and 14 days before the next one. Women who have 30 day cycles can expect to ovulate 16 days after the last period, which is 14 days before the next one. Therefore, it is not possible to get pregnant on the day before you get your period, the last day of your cycle. There is an important exception to this, however. Women who have irregular cycles cannot predict when will get their next period.