Looking at scientific research carried out a few years ago it reads that amongst 10 patients* tested with 25mg of thc ( 0.1g of strong 25% thc bud ) all 10 tested below the 5ng threshold after 24 hours but 2 would have failed the test after 16 hours.
So in short if you smoke more that 0.1 grams you may not be safe to drive within 24hours. Safe from having to do a blood test back at station that is.
http://www.orasure.com/docs/pdfs/pr...uana-Use-by-Oral-Fluid-and-Urine-Analysis.pdf *Numbers in the saliva test chart are diluted numbers so remember to multiply by 3 to get the true figure of ng in saliva that would be detected by police.
Seeing as prosecution would be achieved using a blood test ive done some research on that too and here is a snap shot of my findings.
Remember that 2ng in blood is the legal limit for Driving with drugs in the system in the UK and blood and saliva will not correspond.
I hope this is useful in helping you guys keep your licences , this is just for information purposes only and i havent double checked this info . im not a doctor or a lawyer and i take no responsibility for your choices re driving after using cannabis..
Blood test
Blood-based drug tests screen for a wide variety of illicit substances and have
short detection windows for most, meaning they're typically used to establish very recent drug use.
THC can be undetectable by blood test as soon as six hours after it enters your system — even though it's still there in trace amounts — and
heavy smokers may test positive for up to 24 hours.
https://mic.com/articles/168783/how-long-does-marijuana-stay-in-your-system-how-thc-blood-tests-work-and-what-you-should-know#.NnFtwl4GK
Delta-9-THC concentration usually drops
below 5 ng/mL within 3-4 hours post dose. Frequent users may have longer detection times. (2ng is the uk limit)
http://www.drugdetection.net/drug.htm
While patients seem to control their individual doses by varying how deeply they inhale, the average amount of THC in the blood dropped to 60% of the peak at 15 min after the last inhale and to 20% at 30 min.
By the 2 hour mark, THC levels were below 5 ng/ml.
It took between 3 to 12 hours for THC to drop below detection limits (0.5 ng/ml) for the low-dose group and from 6 to 27 hours for the high-dose group of the study. However, the subjects of the study were not regular marijuana smokers, which explains why THC levels fell so quickly
.
http://www.truthonpot.com/2013/03/28/how-long-does-marijuana-stay-in-your-system/
The highest THC blood concentrations — around 38 micrograms per liter — were seen just 10 minutes after smoking. But after half an hour, concentrations had decreased to about 10 micrograms per liter, on average, and
by 1.4 hours, levels had decreased to about 4 micrograms per liter.
http://www.livescience.com/53578-marijuana-driving-thc-blood-test.html
Blood tests, unlike urinalysis, detect the presence illicit drugs, not inactive drug metabolites. In general,
THC only remains detectable in the blood of cannabis consumers for a few hours (though low, residual levels may be detected in chronic smokers for up to 12-24+ hours if more sensitive technology is used). Because of this narrow detection window, blood tests are typically only administered in the workplace post-accident in order to estimate recent cannabis consumption. Therefore, most after-hours consumers have little to fear from a blood screen.
http://norml.org/marijuana/drug-testing/item/the-abcs-of-marijuana-and-drug-testing
it won’t stay in your blood stream long: it actually becomes
undetectable by blood tests after no more than four to eight hours. In urine tests, it will be detectable for an even shorter time.
http://greenito.com/news/how-long-thc-detectable-blood/
That means a lab test would only find a trace amount of THC in the blood of occasional smokers after
a few hours. "You could have smoked a good amount, just waited two hours, still be pretty intoxicated and yet pass the drug test [for driving]," says Haney.
*** i have no idea what the limit is for the drug driving test he refer to here it maye not be the case wherever you are.
And if you eat the weed instead of smoking it, Haney says, your blood never carries that much THC. "With oral THC, it takes several hours for [blood THC] to peak, but it remains very low compared to the smoked route, even though they're very high. It's a hundredfold difference," she says.
http://www.npr.org/sections/health-shots/2016/02/09/466147956/why-its-so-hard-to-make-a-solid-test-for-driving-while-stoned
