1. DNA: The root of a hair contains DNA, which can be used for genetic identification. Even if the root isn't present, mitochondrial DNA, found in the hair shaft itself, can still be extracted and used to establish a maternal lineage. This is crucial in forensics and genealogy.
2. Drug and Toxin Exposure: Hair acts like a historical record, trapping substances that circulate in the bloodstream. Analysis of hair can determine if someone has used drugs (like cocaine, opioids, or marijuana), been exposed to toxins (like arsenic or lead), or even certain medications over a period of weeks or months. The length of the hair section analyzed correlates to the time frame.
3. Sex: DNA analysis from the hair root can determine sex. Furthermore, even without a root, analysis of the hair's structure can sometimes indicate sex, though with less certainty. Male hair tends to be thicker than female hair.
4. Race/Ancestry: While not a perfect indicator, certain physical characteristics of hair, such as shape, texture, and pigmentation, can suggest a person's ancestral origin. DNA analysis provides more accurate information about a person's race/ancestry.
5. Nutritional Deficiencies: Hair analysis, though somewhat controversial and not always reliable, can sometimes indicate deficiencies in certain vitamins and minerals. However, it is not generally accepted in the medical community as a primary diagnostic tool for nutritional deficiencies due to the potential for external contamination and inconsistent results. Medical professionals typically rely on blood tests for accurate nutritional assessment.