‘Identifying’ hair – Testing – What is possible when it comes to testing?

Finding a hair in your food can be rather off-putting. Whether hair enters a product accidentally or as a result of deliberate sabotage, its presence can put a brand’s reputation at huge risk. Hair is classified as a physical contaminant in terms of HACCP, and its presence in a product may indicate a lack in GMP and/or TACCP controls. Identifying the origin of foreign hair strands in a product is an important step in managing customer complaints, completing root-cause analyses, and preventing similar incidents from reoccurring.

Despite what some forensic-science crime dramas imply, it is not always possible to identify the exact person to whom a hair belongs. DNA-based identification methods require the root of the hair follicle to be attached. Even when the follicle root is intact, however, it is not always possible to extract a sufficient amount of DNA from it to produce a reliable result.

So what is feasible, when it comes to identifying ‘foreign’ hair?

Figure 1. Morphology of a hair follicle

Origin

One of the first analytical avenues to investigate is the origin of the foreign hair. Human hair, animal hair and synthetic fibres all have unique elemental profiles that can be used for identification.

Furthermore, human hair and animal hair have several different morphological features that can be used to confirm the hair’s origin. For example, the medulla diameter of human hair is less than one third of the follicle diameter, while animal hair has a medulla diameter that is greater than half of the follicle diameter.

Ethnicity

Should a foreign hair be identified as a human hair, additional features of the hair can be assessed to determine the ethnicity of the individual from whom it originated. There are some distinct morphological differences between European, Asian and African human hair, such as the longitudinal and cross-sectional shape.

Gender and age

Without positive controls, it is difficult to determine whether a foreign hair belongs to a male or female person, or the age of the person.

If you are interested in investigating the origin of a foreign hair sample, or would like to know more on this topic, please contact us.