Head Hair Testing
Head hair testing provides drug use history up to 90 days ago.
Depending on the length of the donor's hair, standard head hair testing can provide a single "snapshot" of drug or alcohol use history up to 90 days in the past. This test is only available to donors with head hair that is at least 1½ inches in length. Each half-inch is approximately a 30-day period.

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Body Hair Testing
Body hair testing provides drug use history between 30 days and up to a year in the past.
Unlike head hair that grows at a relatively constant rate, body hair grows at different and slower rates so it isn't possible to determine history trends or exactly how far into the past the test can detect, but it could be up to a year. Alcohol testing cannot be done in body hair.
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Environmental Exposure Hair Testing
Environmental exposure hair testing can show exposure to an environment where drug abuse occurred.
Primarily for children and teenagers, environmental exposure hair testing can help determine if an individual was in an environment where drugs were being used. Since the contents of the hair are not being tested and only the residue on the outside of the hair, testing must occur as soon as possible and before the donor washes their hair.