Why SPF 30 is the new SPF 50
By KARL ROOS - April 4, 2018
“Properly applied SPF 50 sunscreen blocks 98 percent of UVB rays, while an SPF 30 sunscreen blocks 97 percent of sunburn rays – the difference being one percentage point.“
In theory, an SPF 50 sunscreen would allow users to stay out in the sun fifty times longer than they normally could without sunscreen, while SPF 30 would imply that users can stay out thirty times longer before getting sunburned. But for high-SPF sunscreens, theory and reality are different things.
People often assume that they are given almost twice the amount of protection by applying a SPF 50 sunscreen compared to one that has SPF 30. This is not true, since the extra protection offered by a higher SPF value is negligible:
Properly applied SPF 50 sunscreen blocks 98 percent of UVB rays, while an SPF 30 sunscreen blocks 97 percent of sunburn rays – the difference being one percentage point.
Stating an SPF number higher than 30 on a sunscreen is no more than a sales trick luring people into a false sense of security. So, let’s dive into some of the research that has been conducted on the topic.
SPF results are often not accurate
When Procter and Gamble tested a competitor’s SPF 100 product at five different labs the results varied between SPF 37 and SPF 75. It was determined that a very small difference in testing conditions dramatically influenced the measured SPF. For example, a 1.7 percent change in light transmission yields a SPF measurement of 37 instead of 100, and very small differences in application thickness can lead to similar results. Because of the way SPF values are measured, errors are more dramatic for high SPF products.
UVB and UVA rays – what’s the difference?
A product’s actual sun protection is determined by its ability to protect you from both UVB and UVA rays. UVB rays make you tanned, and too much exposure to them has been correlated to the emergence of skin cancer. UVA rays suppress the immune system, lead to the creation of harmful free radicals in the skin, and exposure to them may also lead to skin cancer. Unlike UVB rays, UVA rays do not make you tanned. Therefore, it is impossible to know whether you have been exposed to a risky amount of UVA rays.
The problem with high SPF sunscreens is the fact that the SPF value has little to do with a products ability to shield the skin from UVA rays. Since the chemical compounds many sunscreen manufactures use for sun protection do not mix well together, SPF 50 sunscreens are often unable to protect the user from harmful UVA rays. Zinc Oxide – the compound used in Suntribe’s sunscreen – offers protection against both UVA and UVB rays.
Health risks associated with High-SPF products
As a final case in point, High-SPF products may come with significant health risks, since the concentration of sun-filtering chemicals is much higher than in products with lower SPF values. Some of the ingredients used in SPF 50 products have been linked to tissue damage and hormone disruption, and other trigger allergic skin reactions. If high SPF products actually offered better protection than those with lower SPF values, the higher exposure to potentially harmful chemicals could have been worth it. But they don’t, so choosing a sunscreen with less chemicals makes a whole lot of sense.
Here, it is worth mentioning that EWG – a non-profit environmental research organisation specialising in sunscreen products – are of the opinion that manufactures should stop selling high-SPF products altogether. Australian authorities have already put a cap on SPF values at 30, and European and Japanese regulators at 50. Even though such policy decisions have not yet been implemented in the USA, the FDA is currently working towards implementing similar caps.