The study took hair samples from more than 300 individuals from 9 countries to determine the different metal deposits in both the hair and scalp, the results of which have been analysed in an article published in the peer-reviewed International Journal of Cosmetic Science.
The team, which was headed up by Simon Godfrey and Jennifer Marsh, wanted to build on previous studies which have removed exogenous materials prior to samples being analysed.
New approach to hair and scalp analysis
“While this is needed when using hair analysis to probe the impact of the local environment on endogenous metal levels, it's not relevant for understanding exactly what is on hair as a result of contact with its daily environment,” the study authors state.
The scientists also say that they retained the exogenous materials because they wanted to learn more about the redox active metals, including copper and iron, and how they can impact the health of the hair follicle, including external factors such as UV rays and hair colouring.
“The levels measured vary widely, even within the narrow geography of each hair sampling location. The levels of calcium, magnesium, copper and iron were not correlated, and within each location there are expected to be individuals with high metal levels,” the authors stated.
Big variance in survey results
The study found that levels of metals increased from root to tip for calcium, magnesium and copper, largely attributed to environmental forces, while levels of redox metals were comparable between individuals who coloured or did not colour their hair.
Additionally, the results also showed that those samples with water hardness ions were statistically much higher for individuals who coloured their hair.
Concluding on the results, the researchers say that controlling metal on hair using methods such as preventing binding during environmental contact or controlling their ability to cause hair damage, could improve the perceived health of hair.