Natural nano sunscreens - a contradiction?

Sun care specialist Julian Hewitt said that natural effective sunscreens are possible if the nanoparticles used in the mineral filters pose no barrier to natural classification, during his talk at In-Cosmetics, Amsterdam.

Hewitt, from Croda Chemicals Europe, highlighted the current options available to natural sunscreen formulators, whilst presenting two of the company's ingredients.

Mineral sunscreens for natural formulations Similar to the market for natural and organic personal care products as a whole, natural sunscreens suffer from a a lack of internationally recognised criteria.

Natural claims can be based on a number of very different criteria ranging from the inclusion of certain botanical ingredients to percentages of certified natural ingredients in the formula.

Regarding the filter itself, mineral sunscreens such as titanium dioxide and zinc oxide are often the choice of natural formulators according to Hewitt as all organic and chemical filters are regarded as synthetic.

Although increasing research is being carried out on a range of vegetable derived UV protective ingredients these are not yet approved as filters as they have not undergone the necessary safety and efficacy evaluation, he explained.

Problems with particle size However, the efficacy of the mineral filters is reliant on their particle size - a particle size that is likely to fall within the nano range, said Hewitt.

The average size of titanium dioxide particles is below 100 nm, and although zinc oxide particles are on average slightly bigger there will always be some smaller than 100nm, he explained.

For Hewitt the presence of nanoparticles in a formulation does not stop the product being 'natural' and he references a large body of literature that suggests they are safe, however the 'nanodebate' is by no means concluded.

Early this year the Soil Association announced that it will not give its organic certification to any product that contains nanoparticles, taking action 'against this hazardous, potentially toxic technology that poses a serious new threat to human health'.

This makes an organic sunscreen impossible under Soil Association standards with today's technology and available ingredients.

Croda's answer to natural sunscreens Hewitt then went on to present two of Croda's ingredients aimed at natural formulators:

Solaveil CT 300, a titanium-based filter, and CZ 300, its zinc-based counterpart.

According to Hewitt the ingredients have a particle size that maximises UV protection whilst remaining transparent on application.

The products contain a naturally derived carrier medium capric/caprylic triglyceride and a vegetable derived dispersing material.

The two ingredients can be combined to deliver a high SPF protection with UVA protection levels acceptable to the new protection criteria, said Hewitt.