Effects of Sun and Pollutants on Hair

Effects of Sun and Pollutants on Hair

It is perhaps surprising that sun protection has not yet become a proposition in hair

care. Skin care product messages often cross over to the hair care world – and clearly

sun protection for hair is big news.

 

Furthermore, it is well recognized that hair structure

and properties can be considerably compromised by sunlight. There is already a

reasonably-sized scientific literature relating to the effects of sun on hair (and wool) –

but the lack of any uniformity in weathering conditions makes it very difficult to draw

conclusions about the severity of changes relative to other insults. Additionally, this

literature teaches of the influence of other not-so- well-understood variables such as

hair color, environmental conditions, etc. Perhaps the greatest benefit of the existing

literature is to serve as a guideline for re-starting this work in a more controlled and

uniform manner. Initial efforts will involve measuring the severity of photochemical

degradation in hair as a function of some key variables.

 

Assessment will involve cysteic acid measurement (surface oxidation), tensile properties (damage in microfibrils), DSC (damage in matrix) and color change (melanin degradation).

Current hair pollution research areas at TRI:

UV Radiation • Particulates (PM) • Ozone

UV impact on hair & screening absorbing actives/formulations

Test method to evaluate PM anti-pollution formulations

We have developed a test method to evaluate the efficacies of different PM anti-pollution hair formulations by means of (a) color (L), (b) dry combing (only for non-conditioning agents) and (c) scanning electron microscopy (SEM).

Hair oxidation by gaseous pollutants: ozone

Oxidation by ozone causes:

• Hair fiber stiffening in the Hookean and Post yield regions.


• Resistance to breakage & heat.


• Deterioration of hair surface
properties.

Crosslinking of hair proteins may cause changes in the thermal properties & break resistance.

On-going research:

• Investigating whether salt bridges and/or covalent bonds influence


the stability of hair proteins;

• Explore humidity impact on hair oxidation by ozone;

• Optimize method for testing

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