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Hair Analysis

Hair analysis can be used to check if people are blood relatives. Forensic hair analysis can be done to help identify a criminal by evaluating hair structure and DNA. Hair samples are tested with specific chemicals and looked at under a microscope. Hair analysis can also be used to check for poisoning caused by metals such as lead or mercury. But hair analysis alone usually is not used for this type of testing.

Hair is a protein that grows out of hair follicles camera.gif in the skin. Normally, a hair grows in the hair follicle for many months, stops growing, and falls out. A new hair then grows in the follicle. It takes weeks for a hair sample to show changes in the body, because hair grows slowly. Hair samples do not show recent changes in the body, such as drug use within the past few days. But a hair analysis may show drug use or exposure to chemicals that occurred over the last few months.

Why It Is Done

Hair analysis is used to provide DNA evidence for criminal and paternity cases. For DNA testing, the root of one hair is needed to analyze DNA and to establish a person's genetic makeup.

Hair analysis is less commonly used to test for heavy metals in the body, such as lead, mercury, and arsenic.

How To Prepare

If you have a hair analysis done, the laboratory will give you specific instructions on how to prepare your hair. Hair preparation and the part of your body from which the hair is taken varies. In general, your hair should be washed and free of any hair care products.

You may be asked to sign a consent form that says you understand the risks of the test and agree to have it done.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

Hair analysis is done by collecting a hair sample and sending it to a laboratory.

Hair samples are taken from a specific part of the body, such as from the back of the scalp by the neck or from the pubic area. Hair samples are generally collected from the section of the hair closest to the skin. Hair close to the skin or scalp includes the most recent growth, which provides the most accurate information about what has occurred recently in the body.

Hair samples are washed in special chemicals before testing.

DNA profiles

Hair samples for DNA analysis will be gathered by laboratory personnel or law enforcement officials or a forensic examiner. For DNA testing, the hair must include the root. This requires that the hair be plucked, not cut.

Heavy metal analysis

If you are collecting your own hair sample, follow the instructions given to you by the laboratory. In general, you will be asked to:

  • Clip a small sample of your hair (usually about a spoonful) from the nape of your neck. The sample should be 1 in. (2.5 cm) to 1.5 in. (4 cm) long and should include the new growth closest to the scalp.
  • Put the clippings in a plastic bag and seal it.
  • Send the samples to the laboratory along with information about the type of hair treatments you have used, including shampoos, conditioners, colorings, bleaches, and permanents. Information about your age, height, weight, sex, and whether you smoke may also be requested by the laboratory.

WebMD Medical Reference from Healthwise

Last Updated: November 07, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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