Test Overview

Hair analysis is done by evaluating hair structure and DNA from cells attached to the root of the hair. It can be used to find out if people are related. Forensic hair analysis can be done to help identify a person who may have been present at a crime scene. 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 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 done by evaluating hair structure and DNA from cells attached to the root of the hair. It can be used to find out if people are related. Forensic hair analysis can be done to help identify a person who may have been present at a crime scene.

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

Hair samples that are taken close to the root can show what drugs were used up to 3 months before the test.

How To Prepare

If you have a hair analysis done, the lab 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.

How It Is Done

Hair analysis is done by collecting a hair sample and sending it to a laboratory. If a DNA test is done on the hair, then the hair collected needs to have the root attached.

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 2.5 cm (1 in.) to 4 cm (2 in.) 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, colourings, bleaches, and permanents. Information about your age, height, weight, sex, and whether you smoke may also be requested by the laboratory.

Drug testing

Hair samples that are taken close to the root can show what drugs were used up to 3 months before the test.

How It Feels

There is generally no pain or discomfort associated with this test. But if you have to pluck a hair for a DNA test, this may cause some minor discomfort.

Risks

There are no known risks from having this test.

Results

Heavy metal analysis

The results of hair analysis are usually complete within 3 weeks. You or your doctor will receive a report listing the levels of minerals and heavy metals in your hair. Several things need to be considered before testing for heavy metal exposure.

There is no standard procedure for cutting, washing, and analyzing hair. Different labs may report different results from the same hair sample. In fact, the same lab may report different results for separate hairs from a common sample. Standards for testing do not exist. Any hair analysis to detect the presence or absence of minerals, nutrients, or toxic metals in the body should be confirmed by testing blood and urine samples.

What the hair sample contains is determined not only by nutrition and internal metabolism but also by external substances. Air pollution, mineral content of the water supply, exposure to industrial waste, shampoos, hair dyes, hair sprays, permanents, and bleaches may raise or lower the levels of certain minerals in the hair. Also, the use of medicines such as birth control pills can change the mineral concentration of hair.