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Addiction: Cannabis

How long does it persist in the body?

bus/train driver or pilot
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Cannabis has a long half-life. In other words, traces of the drug will live on in the body a long time after someone has had a smoke. This is because THC has a very low solubility in water and gets lodged in body fat and tissue. Smoking a joint a couple of nights a week may take 21–28 days to clear the system and it will take longer in an overweight person. Heavy cannabis use can also be detected for around 42–56 days after cessation. Testing for cannabis use is done by testing urine and some people who drive transport or use machinery may be randomly tested at work.

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