Drug and Alcohol Testing Q&A - 2007

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Re: Why did donor who admits to use test negative?

From: Robert Swotinsky MD
Password: orange
Date: 16 Dec 2007
Time: 07:56:59 -0800
Remote Name: 71.233.246.147

Comments

EtG can produce positive results at low cutoff values due to exposure from ethanol in mouthwash and, at very low cutoffs, from ethanol in hand sanitizers.

How does one explain a negative EtG result in someone who said he/she recently consumed ethanol? There are numerous potential reasons, including:

1) EtG concentration below the cutoff value,

2) Substituted specimen,

3) Use of an adulterant that interfered with the EtG assay,

4) Operator error or misinterpretation -- of particular concern if this is an on-site/rapid test,

5) The donor did not actually recently consume ethanol before the test.  Donors may say things to those conducting the tests to jerk our chains -- Hey, if your test is so good, why didn't it catch me!?

6) The test was not actually for EtG.  Double check the lab report and verify that it was for EtG, not ethanol.

No doubt there are other potential explanations, too.