A new scale for describing the range of human skin colours will help combat underrepresentation in research and replace subjective approaches for describing skin colour, say researchers.
The five-point Eumelanin Human Skin Colour Scale has been developed by members of the British Association of Dermatologists’ Lexicon Group to improve how skin is described by researchers and healthcare professionals.
The scale is based on published data for a measurement called the melanin index and is calculated by measuring the amount of light reflected from the skin.
Different skin colours reflect different amounts of light with lighter skin colours reflecting more and darker ones reflecting less.
The researchers used this existing data to divide the known range of the melanin index into five sections: Eumelanin Low; Eumelanin Intermediate Low; Eumelanin Intermediate; Eumelanin Intermediate High; and Eumelanin High.
Currently the most commonly used scale for describing skin colour is the Fitzpatrick scale, which was developed to describe how human skin reacts to sunlight, but never intended as a scale for describing skin colour.
As a result, the 1975-developed system underrepresented darker skin colours.
A further limitation is that it is based on subjective criteria (ie, perceived skin tone).
According to Lexicon Group researchers, benefits of this new standardised approach include making it easier to analyse and compare studies where skin colour is an important variable, and making it possible to talk precisely about diseases which are more common or more severe in people with different skin colours.
Another potential plus is providing researchers with more tools to spot underrepresentation in research.
“For a long time, healthcare professionals and researchers have been missing a simple tool in their toolboxes: an evidence-based approach to describing skin colour,” said Dr Ophelia Dadzie, Chair of the British Association of Dermatologists’ Lexicon Group.
“There are often instances in research and in medicine where skin colour, rather than say ethnicity, is an important variable.
“Being able to objectively describe this feature will help us talk more accurately about who diseases impact, will help us analyse and compare research more easily, and enable us to spot underrepresentation more clearly.
“An important thing that we would like to emphasise is that this is not a replacement for talking about ethnicity, or any other characteristic.
“Where ethnicity is the relevant factor, then skin colour should not be used as euphemism for this, and vice-versa.”
An outdated model?
While the Fitzpatrick phototyping scale is widely used to measure the amount of melanin in the skin after exposure to the sun, the industry is moving away from this system as a way of classifying skin colour.
While Lexicon Group’s new system is designed to facilitate better communication in the healthcare sphere, the recently announced Naz-Westland Index aims to reinvent the way the beauty industry classifies skin tone to empower consumers’ buying choices.
Created by EX1 Cosmetics founder Farah Naz and Leeds University professor Stephen Westland, research underpinning the index revealed that undertones of red, red-plus, neutral, yellow and green (YG) and yellow and green-plus exist within the human gamut.
