Apply with caution

Sunscreens can be broadly categorised as either chemical, which are absorbed into the skin and which absorb ultra-violet rays, or physical (mineral), which sit on top of the skin and reflect UV rays.

Whilst the mainstream brands in this report typically produce chemical sunscreens, and ‘natural products’ companies produce physical sunscreens, some products now also contain a mixture of both active ingredients.

When exposed to the sun, two types of ultra-violet radiation are of concern: short-wave UVB rays, which are more intense and are the primary cause of sunburn, and long-wave UVA rays, which penetrate the skin more deeply and are the dominant tanning ray.

Both types of UV are contributing factors to skin cancer, but until relatively recently the significance of UVA rays was not fully known. This, coupled with research that indicated some companies claimed their products provided more sun protection than was the case, led to changes in non-legally binding recommendations from the European Commission in 2006. It seems that most manufacturers have voluntarily complied, leading to better sun protection being available in Europe than in the USA.

A product’s sunburn protection factor (SPF) refers to the level of UVB protection that it provides. The EU guidelines now state that the level of UVA protection should be at least a third of the SPF indicated on the packaging. So, whilst a product might offer UVB protection of SPF 30, if its UVA protection is equivalent to SPF 5 it would not be able to display an SPF figure of greater than 15. Consequently, very high SPF products are disappearing from the shelves along with products that claim to give complete protection, such as sun block.

Products that offer broad-spectrum protection are recommended, and both chemical and physical sunscreens can provide this. However, a number of ingredients found in chemical sunscreens have raised safety concerns.

Physical sunscreens and the nano factor

The active ingredients in physical sunscreens are zinc oxide and titanium dioxide. These ingredients can occur as nano-particles – microscopic particles about 1/50,000 the width of a human hair. Safety concerns regarding the use of nano-particles are as yet unresolved, and the regulatory framework for assessing their use continues to lag far behind developments in the cosmetics sector.

In our last Buyers’ Guide to sunscreens we recommended that, in line with the precautionary principle, products containing nano-particles are avoided. Since then, however, the well-regarded Environmental Working Group (EWG) have begun to recommend some products that may contain nano-sized ingredients. They found that consumers using sunscreens without zinc oxide and titanium dioxide were being exposed to an average of 20% more UVA radiation, with associated health impacts. They were also being exposed to a greater number of hazardous ingredients through the use of chemical sunscreens. The study concluded:
“On balance, EWG researchers found that zinc and titanium-based formulations are among the safest, most effective sunscreens on the market based on available evidence. The easy way out of the nano debate would be to steer people clear of zinc and titanium sunscreens with a call for more data. In the process, such a position would implicitly recommend sunscreen ingredients that don’t work, that break down soon after they are applied, that offer only marginal UVA protection, or that absorb through the skin”.[2]

However, EWG stress that their position would be different if the product analysed did not protect human health like sunscreen does, and that sprays and powders containing nano-particles should be avoided.

Some natural products companies still offer sunscreens with micro-sized rather than nano-sized zinc oxide or titanium dioxide. However, the EWG note that both nano and micro-sized particles can be toxic if they penetrate the skin.

We have divided the Best Buy companies into those that use nano-particles and those that use micronised (non-nano).

Physical or mineral sunscreens are less likely to cause skin irritations and allergic reactions as they are not absorbed into the skin. However, this means that they can leave a residual white coating on the skin – possibly not the look you are after on the beach! The smaller the particle size the less chance there is of looking luminous.

Despite the fact that they can now be Best Buys, companies that use nanoparticles in their sunscreens will still lose half a mark in our Pollution and Toxics category. The environmental impacts of nanoparticles are not fully understood, but concerns have been raised about the build up of this novel pollutant in ecological systems. Once again research seems to be lagging way behind technological developments.

This buyers' guide is part of a Special Report on Cosmetics & Toiletries.  See what's in the rest of the report.

References

1 http://bx.businessweek.com/loreal-group/ 
2 http://www.ewg.org/nanotechnology-sunscreens 
3 http://www.skincancer.org/prevention/uva-and-uvb/understanding-uva-and-uvb 
4 http://breakingnews.ewg.org/2012sunscreen/

(all websites viewed July 2012)