Testing Types and Comparisons

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