What's up with acronyms in sunscreens?
Have you ever wondered what all those acronyms and terms mean when you are buying sunscreen? Today, we are going to explain as many of them as we can because in all honesty, there are a lot and they can be confusing. Let’s start with some basic acronyms.
Controversies in SPF
If you dig a little, you will find many controversies in sunscreen use. One such controversy is about whether there is any value in selecting sunscreens above SPF 50. While some people advocate selecting sunscreens with as high SPF value as possible, others suggest that values above 50 are detrimental. We will attempt to summarize the two major points of debate and give our opinion.
Point 1 - ‘SPF above 50 is unnecessary’
The first point is based on the fact that there is a rapidly diminishing rate of return for UV protection beyond SPF 50. The actual reason is because of the minimal change in UV penetration, but to put it in practical terms: SPF 50 means that someone who normally burns in 5 minutes in the sun will require 250 minutes in the sun to burn, which is 4 hours and 10 minutes. Since sunscreen is supposed to be applied every 1.5 - 2 hours anyways due to the natural progressive breakdown of the active ingredients on the skin, you shouldn’t need so much SPF that it will last 4 hours.
While this argument has some good points, it may not be realistic for most people. Let’s break it down mathematically.
The reported SPF is measured using 2mg/cm^2 of sunscreen applied evenly on the skin. The surface area of an average adult male is 19000cm^2, the average female is 16000cm^2, and the average 10 year old child is 11400cm^2. Let’s just use the average adult male as an example to calculate how much sunscreen you actually need to put on to achieve the labelled SPF.
Since most people don’t apply sunscreen all over our body, we will only calculate it based on sun exposed areas. If you only take the face, upper half of chest and back, arms, legs, and feet, that accumulates to 76.5% of your total body surface area. To apply 2mg/cm^2 of sunscreen to this area, you would need 29 grams of sunscreen per application. Here is where the ideal scenario deviates from reality. Most affordable bottles of 90 grams of sunscreen lotion cost between $10-15. Essentially, this means that the bottle of sunscreen that you just bought is going to last you 4.5 to 6 hours only. Price aside, most people simply do not apply enough sunscreen to run through a whole bottle in 6 hours.
This means that most people are not actually getting the promised SPF. We do not suggest or agree with this type of practice, but if that is the reality of the situation, then the best option is to recommend higher than 50 SPF sunscreen.
Point 2 - ‘Getting a sunburn will remind you to apply more sunscreen.’
Some people recommend SPF of 50 or lower so that you can use sunburn as a clinical indicator that you should reapply your sunscreen. This sounds counterproductive and silly but it actually had some historic value. Old sunscreens only protected against UVB, as UVA does not typically cause immediately noticeable skin damage. Because of this, sunscreens that have a lot of protection against UVB will mask the damage that UVA is doing. For example, if you use a SPF of 100, you will unlikely get burned after an hour in the sun, but if that sunscreen does not have UVA protection, you would get an hour worth of UVA exposure thinking that you are protected.
While this may have had some value historically, sunscreens have now adapted to the concept of UVA damage and now produce broad spectrum sunscreens. Furthermore, as of December 2012, FDA has mandated that all products labeled with the term broad spectrum must provide protection against UVA and UVB. Over the past few years, these products have become widely available for purchase.
Sunscreen quick tips
To sum it up, here are some basic tips for sunscreens!
That's all we have to say today folks! Look forward to our next article as we build on this topic and talk about tanning!