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
|