Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Mary Hill on 06/06/2009 19:30:02

Title: Are mineral sunscreens effective?
Post by: Mary Hill on 06/06/2009 19:30:02

Mary Hill  asked the Naked Scientists:
   
Dear Chris,

Please would you advise me as to whether natural mineral sunscreens using titanium dioxide and zinc oxide to reflect UV rays away from the skin are as effective as chemical sunscreens?

Your programme is absolutely fantastic (http://www.thenakedscientists.com/HTML/podcasts/)!

Many thanks

Mary Hill

What do you think?

Title: Are mineral sunscreens effective?
Post by: Bored chemist on 06/06/2009 19:43:28

TiO2 and ZnO are both chemicals.

Title: Are mineral sunscreens effective?
Post by: Chemistry4me on 07/06/2009 00:33:31

Apparently...

http://serendip.brynmawr.edu/biology/b103/f02/web1/vculler.html

Title: Are mineral sunscreens effective?
Post by: Yomi on 08/06/2009 07:18:52

he titanium dioxide and zinc oxide used in Mexitan is micronized, with a coated variable particle size in the range of 100-200nm. (Nanoparticles are considered to be less than 100nm in size). This allows our sunscreen lotions to be more cosmetically appealing compared to coarser particles. The protection is less visible, yet remains on the skin's surface.

Title: Are mineral sunscreens effective?
Post by: Raghavendra on 08/06/2009 07:53:54

adsorption... causes the effect

Title: Are mineral sunscreens effective?
Post by: Yomi on 08/06/2009 07:55:39

they save us from getting skin cancer so adsorption is not to be worried.......

Title: Are mineral sunscreens effective?
Post by: Raghavendra on 08/06/2009 09:02:22

 But the DNA & RNA depend on that....

Title: Are mineral sunscreens effective?
Post by: Yomi on 08/06/2009 09:04:24

depends on what please specify........

Title: Are mineral sunscreens effective?
Post by: Kevan Gelling on 08/07/2009 12:50:59

Is there any evidence that sunscreens are effective at preventing skin cancer?

There's this ambiguous statement from Cancer Research UK (http://info.cancerresearchuk.org/healthyliving/sunsmart/skin-cancer-facts/howdoweknow/sunprotection/#Sunscreens) which suggests that they don't have any evidence:

Quote

Some researchers have failed to show that using sunscreens can lower the risk of melanoma.

Whereas here's quote from Wikipedia (http://en.wikipedia.org/wiki/Skin_cancer#Skin_cancer_as_a_group) with 6 citations that suggest sunscreens don't prevent skin cancer:

Quote

It has been found that sunscreen use is correlated with malignant melanoma

Title: Are mineral sunscreens effective?
Post by: Kevan Gelling on 08/07/2009 14:10:55

Here is more background to the sunscreen debate - from Wikipedia (http://en.wikipedia.org/wiki/Sunscreen_controversy).

It would appear that sunscreen did not protect against UVA light.  Modern sunscreens do (look for the 5 stars UVA circle on the back of the bottle).

Title: Are mineral sunscreens effective?
Post by: mad scientist on 10/07/2009 13:13:55

Actually the answer is depends but in general the inorganic sunscreens are more effective as they block or adsorb both UV A and UV B wavelengths.
Most chemicals sunscreens up until a few years ago only protected against UV B radiation until the FDA approved Parsol 1789 or avobenzone.
Plus if you are a fisherman like me you don't want the chemical sunscreens on your hands/equipment. The ethylhexyl methoxy cinnimate is an effective repellant for fish and geese and other animals.
Did you know that sunscreens are regulated as an over the counter drug?