What’s the correct sunblock dosage?
Friday, 23 November 2007
Yuri Ebihara for Shiseido Anessa
I was browsing through a beauty forum and came across some interesting discussions regarding the dosage of sunblock application. According to some of the girls, we need to apply half a teaspoon of sunblock on our face in order to enjoy the full SPF. On top of that, we need to reapply every two hours to maintain the protection.
Well, these all make sense but isn’t half a teaspoon too much considering how most sunblock formulations are despite what they promise? Either we’ll end up looking ghostly with a white overcast or we’ll end up looking like a greasy pancake.
In fact, based on what I’ve picked out from the Wiki, 1/4 to 1/3 of a teaspoon of sunblock is apparently adequate for our face.
Dosing for sunscreen can be calculated using the formula for body surface area and subsequently subtracting the area covered by clothing that provides effective UV protection. The dose used in FDA sunscreen testing is 2 mg/cm². Provided one assumes an “average” adult build of height 163 cm and weight 68 kg with a 82 cm waist, that adult wearing a bathing suit covering the groin area should apply 29 g (approximately 1 oz) evenly to the uncovered body area. Considering only the face, this translates to about 1/4 to 1/3 of a teaspoon for the average adult face.
But realistically, how do we apply even 1/4 of a teaspoon of sunblock without compromising on how we look? I know I can’t do that with any of the sunblocks I’ve tried.
In addition, I noted the wiki article cited that more recent research at the University of California, Riverside indicates that sunscreen needs to be reapplied within 2 hours in order to remain effective. With makeup on, it’s really quite impossible to reapply sunblock every two hours. And note this: “Not reapplying could even cause more cell damage than not using sunscreen at all, due to the release of extra free radicals from absorbed chemicals.”
As I read that, the first thought that came to mind was, does this research imply that physical or mineral sunblocks are better? Environmental Working Group appears to confirm this.
For those who are confused, physical sunblocks are those that uses titanium dioxide or zinc oxide to reflect or scatter UV radiation before it reaches our skin, although large particles may not reflect every UV rays for full protection. Chemical sunblocks on the other hand, use organic absorber to absorb UV rays and invalid the damage of UV achieving a full blockage of a broad spectrum UV rays. Some sunblocks actually combine both.
Ya, I know. It’s pretty mind boggling. Well, for now, I’m happy to stick to my safest sunblock although I won’t be using 1/4 of a teaspoon for sure. But I’ll attempt to reapply whenever I can.
Read other related entries in the sunblock category.
© www.vivawoman.net copyright notice
______________________________________________________________
Stumble This | 
Get Email | 
Subscribe to RSS
Posted in Sun Protection | 13 Comments »
13 Comments to “What’s the correct sunblock dosage?”
Leave A Comment
(SEO names, unsolicited sales messages and rude comments will be deleted.)Related Posts
- Is higher SPF in sunblocks better?
- Is sunblock different from sunscreen?
- Do I really need to reapply my sunscreen?
- Can adults use sunscreens for babies & kids?
- What’s in a good sunblock?
previous post: Ethnic inspired handmade jewelry
next post: Japanese hairstyles for inspiration
November 24th, 2007 at 7:00 am
What’s The Correct Sunblock Dosage?…
Article examines how much sunblock we should be applying to get the right protection. Also highlights that physical sunblocks maybe better….
December 8th, 2007 at 6:13 am
[...] Beauty and Fashion Tech has Great Beauty Books for Holiday Gifts. Viva Woman checks out what’s the correct sunblock dosage to get sufficient coverage. Temptalia shares her beauty-themed Holiday Gift Guide for Your Very [...]
December 8th, 2007 at 11:02 pm
[...] Beauty and Fashion Tech has Great Beauty Books for Holiday Gifts. Viva Woman checks out what’s the correct sunblock dosage to get sufficient coverage. Temptalia shares her beauty-themed Holiday Gift Guide for Your Very [...]
December 9th, 2007 at 12:01 am
[...] and Fashion Tech has Great Beauty Books for Holiday Gifts.Viva Woman checks out what’s the correct sunblock dosage to get sufficient coverage.Temptalia shares her beauty-themed Holiday Gift Guide for Your [...]
December 9th, 2007 at 3:00 pm
[...] Beauty and Fashion Tech has Great Beauty Books for Holiday Gifts. Viva Woman checks out what’s the correct sunblock dosage to get sufficient coverage. Temptalia shares her beauty-themed Holiday Gift Guide for Your Very [...]
December 9th, 2007 at 3:09 pm
[...] Beauty and Fashion Tech has Great Beauty Books for Holiday Gifts. Viva Woman checks out what’s the correct sunblock dosage to get sufficient coverage. Beauty Secrets Revealed is Running A Christmas Contest. Ellen from Spa [...]
December 10th, 2007 at 6:57 am
[...] Beauty and Fashion Tech has Great Beauty Books for Holiday Gifts. Viva Woman checks out what’s the correct sunblock dosage to get sufficient coverage. Temptalia shares her beauty-themed Holiday Gift Guide for Your Very [...]
December 13th, 2007 at 7:34 am
[...] my earlier entry, What’s The Correct Sunblock Dosage?, I’ve already explained that physical sunblocks are those that uses titanium dioxide or zinc [...]
January 1st, 2008 at 11:32 am
[...] What’s the correct sunblock dosage? [...]
March 6th, 2008 at 9:00 pm
[...] body? 1/4 to 1/3 of a tsp of sunscreen is apparently adequate for our face, as I have examined here. For the rest of our body, I understand it is 1/2 tsp to each arm, 1/2 tsp each to the front and [...]
June 8th, 2009 at 3:05 pm
I think the using a crown metal lid is more accurate than a teaspoon as there is a wide variation in the size and capacity of a teaspoon.
Here is the link to the article in Dermatology Online Journal which describes this method of measuring the recommended sunscreen dosage for each body part:
http://dermatology.cdlib.org/93/letters/sunscreen/castanedo.html
[Reply]
sesame Reply:
June 8th, 2009 at 8:29 pm
Hey Stina: Thanks for the link! It’s very interesting! I have no idea what a crown metal lid is. The picture is useful for a reference. And you’re right – teaspoons do vary in sizes!
[Reply]
July 22nd, 2010 at 1:30 am
[...] Beauty and Fashion Tech has Great Beauty Books for Holiday Gifts. Viva Woman checks out what’s the correct sunblock dosage to obtain sufficient coverage. Temptalia shares her beauty-themed Holiday Gift Guide for Your Very [...]