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Was Your BAC Higher Than Expected? Here Are Two Possible Explanations

On Behalf of | Nov 26, 2013 | Alcohol Testing, Blog, Blood Tests

Was Your BAC Higher Than Expected? Here Are Two Possible Explanations

Determining a person’s BAC is a very complex process, and there are multiple ways for a blood or breath sample to be contaminated or otherwise unreliable. If the testing is done by way of a blood test, two surprising sources of contamination come from an unlikely source: the hospital itself.

One possible source of contamination is draw-site contamination. When blood is drawn from a driver, either for the purposes of BAC determination or to provide medical services, the site on the driver’s arm where the needle is inserted is cleansed with a sterilization agent. Usually, when the test is conducted solely for law enforcement purposes, iodine will be used, as it will not contaminate the results. However, if an alcohol- or ethanol-based agent is used, there is a possibility that it will enter the needle when it goes into the skin, which then ends up mixed in with the driver’s blood in the final sample. Since it only takes a miniscule amount of alcohol in blood to elevate the BAC level to .08, the integrity of the sample would be compromised in this situation. The presence of this additional alcohol can increase the BAC reading by a significant amount.

Another possible source of contamination is alcohol entering through cuts on the body. While alcohol is not absorbed through intact skin, it can be absorbed through open wounds. Therefore, if a driver is at a hospital after a car accident, alcohol that is used to cleanse an open wound can contaminate the blood sample, even if an iodine-based sterilization agent is used at the actual draw site.

There are many possible sources of error in BAC testing, and these are just two of them. It takes a knowledgeable attorney to thoroughly explore and exhaust all of these sources.