| Sample |
Advantages |
Disadvantages |
| Blood |
Excellent for detecting recent use
Can be used to infer impairment
No viable means to be adulterated
|
Invasive, requires blood sample (phlebotomy)
Requires laboratory test
Potential for Chain of Custody Issues
|
| Hair |
Potential for long-term assessment of drug use (up to 90 days)
Relatively non-invasive
Accuracy comparable to blood, oral fluid, and urine
No viable means to be adulterated
|
Expensive, & requires laboratory testing
Can not detect recent drug usage
Drug deposition not uniform among hair types
Potential for Chain of Custody Issues
|
| Oral Fluid |
Excellent for recent use & use within past 2-4 days
Very effective for random testing
Non-invasive
Accuracy comparable to blood, urine and hair
No viable means to be adulterated
|
Some reported instances of “dry mouth”
THC detection window is from ingestion to a maximum of 24 hrs.
Federal government / DOT approvals are lagging workplace acceptance and use
|
| Sweat |
Can monitor accumulated drug use for 3–7 days
Relatively non-invasive
|
Requires laboratory testing
Difficult to get large volumes for confirmation
Environmental contamination possible
Potential for Chain of Custody Issues
Questionable accuracy
|
| Urine |
THC metabolite detection of typically up to 2-3 weeks
Current “gold standard” for DOT and Federal Government Testing
Accuracy comparable to blood, oral fluid, and hair
|
High adulteration potential when collection not witnessed
Not suitable for workplace random testing
Requires special facilities
Relatively high cost
|
