A suncream made from wood: Is this the future of skin care?

Suncream is essential for defending against sunburns, skin cancer, and age-related skin alterations. However, in new research from La Roache-Posay 22% of young adults think that daily suncream use is more harmful than direct sun exposure. In their study, the brand asked 2,000 UK consumers for their views on the myths surrounding sun protection. 19% believed you couldn’t get sunburned within the first 30 minutes of being outside in the sun. This belief rose to 29% for those aged between 25 and 34 years old. 22% thought suncream was only necessary during summer, despite UV rays being present all year round. With so many UK consumers misinformed when it comes to protecting their skin from the sun, there is a growing need for education about prevention of sun-related skin damage.

There are two types of suncream: chemical and physical. Chemical suncreams absorb the UV rays into heat; however, their active ingredients are vulnerable to photo-degradation and free-radical generation (a destabilisation of the suncream’s atomic structure). On the other hand, physical sunblocks scatter and reflect the UV rays on top of the skin. While they offer a broader spectrum of protection, their photo-catalytic nature and small particle size carry a potential risk. The synthetic compounds have adverse side effects on humans and the environment. After growing concerned that common suncream chemicals can get through the skin and into the bloodstream, the demand for eco-friendly and safer alternatives has increased.

Each year, 70 million tonnes of lignin are incinerated as boiler fuel, and by using the material in suncream, we can prevent the destruction of this valuable resource

Indeed, recently there have been increased efforts to replace synthetic UV filters in suncreams with natural substances. Wood is a material that is very effective at scattering light as a result of its cellular structure, absorbing light through one of its components, lignin. The compound is an organic polymer in the cells of many plants which makes them rigid and woody. It also offers sun protection factors (SPFs) that exceed 180. Lignin has a natural phenolic network that forms a shield against ultraviolet light, offering protection against the sun without the need for petroleum-based filters.

The use of lignin as sun protection for skin is promising, particularly as a renewable and waste-free resource. Each year, 70 million tonnes of lignin are incinerated as boiler fuel, and by using the material in suncream, we can prevent the destruction of this valuable resource that occurs currently from not using it to its full potential. By replacing 4% of petro-chemical filters in use currently, eight tonnes of pulp lignin could be diverted from boilers. This change could prevent as much as 24 tonnes of CO₂ from being released.

Lignin is already food-contact approved and is cleared worldwide, regulatory hurdles are expected to be lower than for entirely new molecules

The process of creating the lignin-based suncream involves applying ground wood powder as an additive, blended together with a commercial cosmetic cream. The mixture is stirred in the dark, at room temperature for 24 hours. Samples were then dried and UV transmittance was measured to assess SPF values. The softwood variant in particular increased the SPF threefold, with lignin absorbing from 80% to 95% of total UV radiation. However, lignin turns dark when isolated from woody biomass at high temperatures and/or extreme pH values. This colour change poses an issue for its use as sunscreen; however, when wood powder is used instead, the product maintains its original colour. This occurs due to the absorption and scattering of light that does not occur in isolated lignin, and the wood powders remain lighter in colour than the chocolate brown that develops with raw, technical lignin.

The use of lignin rivals commercial broad-spectrum filters while using just one quarter of the synthetic content. Because lignin is already food-contact approved and is cleared worldwide, regulatory hurdles are expected to be lower than for entirely new molecules. Hopefully in the future, wood powder will find new applications as a renewable and environmentally friendly UV-blocking additive throughout various industries. If this change is widely adopted, the logging industry’s waste could be put to better use as sun protection, proving that the path to a more environmentally friendly cosmetic industry lies in using sustainable resources, rather than fossil fuels or harmful synthetic mixtures.