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particle sunscreen vs. organic sunscreen


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#1 Eva Victoria

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Posted 08 April 2008 - 04:01 PM


PARTICLE SUNSCREEN FILTERS VERSUS ORGANIC SUNSCREEN FILTERS


In my earlier articles I have been talking about the importance of using a photostable sunscreen every day.
Today I would like to explain the difference between chemical and non-chemical sunscreens.

The difference between particle/inorganic/physical/non-chemical sunscreen and organic/chemical sunscreens is that particle filters (ZnO, TiO2) mirror the rays of the sun away. Rreflect the rays away from the skin back to space while chemical sunscreens filter UV rays. Chemical filters "convert" UVR into heat making them harmless for the skin.

While doing so, they loose some of their effectiveness each time. A filter is photostable when it does not loose its original structure in this "heat-converting" process (but after 2h it should be reapplied nevertheless because nothing stays 100% stable in the Sun).

Particle filters do not degrade by the Sun. They are physically act like millions of mirrors on the surface of the skin reflecting the rays away from the skin.

As long as the particle size is over 35nm they do not penetrate the skin (cannot be absorbed into the skin). They should be reapplied after swimming because their uniformity could have been damaged, or after sweating excessively or wiping them off.

Particle filters have high, full value UVA protection (specially ZnO, min concentration: 20%!) when the particle size is normal (250-100nm). Their micronized form (100-35nm) have higher UVB protection but lower UVA protection. They are a lot less whitening as well.

Particle size under 35nm (nano) is not allowed in the EU. (But it is in the US and Australia). Nano particles are extremely high in UVB protection but very poor in the UVA field. They are completely invisible on the skin.

A good advice when you buy a sunscreen and it says particle/ non-chemical sunscreen and it does not leave a white cast on your skin, do not use it! (It is either of nano particles and/or UVA protection is far too low to have any effect!)

Organic filters are usually a cinnamate, or some form of a sulfate or a benzophone. They convert harmful UV rays into heat, hence neutralizing the rays.

They are usually very unstable and difficult to stabilize them. (But it is possible with todays technology!)

Organic filters are many. Butt he most common ones are Octyl Methoxycinnamate (OMC), Avobenzone (AVO), Ecamsol (MexorylSX).

There are very good UVB filters that are allowed by the FDA and Australia and the EU. But he problems start when it comes to good enough UVA protection.

In teh US there is only AVO that is approved by the FDA.

In the EU and AU we have 9 UVA filters!

Parsol 1789 Butyl methoxy dibenzoylmethane AVO BMDM UVAII-I
Escalol 6300 4-methyl benzylidenecamphor MBC
Mexoryl SX Terephtalylidene dicamphor UVAII
sulfonic acid

TDSA
Mexoryl XL Drometrizole trisiloxane DMTS UVAI
Uvinul N 539 Octocrylene OC
Uvinul T 150 Octyltriazone OT
Titanium dioxide TiO2 UVB-UVAII
Zinc oxide ZnO UVAII-I
Tinosorb® M (USAN Bisoctrizole, INCI Methylene Bis-Benzotriazolyl

Tetramethylbutylphenol) UVAI

Tinosorb® S (USAN Bemotrizinol, INCI Bis-Ethylhexyloxyphenol Methoxyphenyl

Triazine) UVAII

Octocrylene

Diethylhexyl Butamido Triazone

The following are the FDA allowable active ingredients in sunscreens:

USA nm max.effect nm

p-Aminobenzoic acid (PABA) up to 15 %. 260-313 283


Avobenzone up to 3%. BMDM 310-400 358

Recently FDA approved:

Mexoryl® SX (USAN Ecamsule, INCI Terephthalylidene Dicamphor Sulfonic Acid) - UVAII absorber used in combination with other ingredients for UVB

Others additionally approved within the EU[ and other parts of the world include:

[/list][/list][/list][/list][/list][/list][*]Mexoryl® XL (INCI Drometrizole Trisiloxane) 290-370 330-350
[*]Neo Heliopan® AP (USAN Bisdisulizole Disodium, INCI Disodium Phenyl Dibenzimidazole Tetrasulfonate)
[*]Uvinul® A Plus (INCI Diethylamino Hydroxybenzoyl Hexyl Benzoate) 352-360 356
[*]Uvinul® T 150 (USAN Octyl Triazone, INCI Ethylhexyl Triazone) 290-320 300-320
[*]Uvasorb® HEB (INCI Diethylhexyl Butamido Triazone)
[*]Parsol® SLX (INCI Polysilicone-15) 310-330 315
[*]Amiloxate (USAN), INCI Isoamyl p-Methoxycinnamate)
[/list] A lot of the ingredients not approved by the FDA are relatively new and developed to absorb UVAII and I.

A good sunscreen is composed of several chemical compounds (particle and organic filters) to be able to achieve full protection against UVB and UVA-rays and to be able to stay photo stable in sunlight!



The best sunscreens available today (obtainable only in/from the EU) are:

Bioderma Photoderm with Tinosorb S+M

La Roche Posay Antihelios with Mexoryl XS+XL

Nivea Light Sensation with Tinosorb and AVO+TiO2 (European edition!)


Pleaseclick on the link bellow for more info about UVA rays and the importance of good protection against them:

http://www.imminst.o...ous-t20235.html

http://www.imminst.o...d33-t20109.html

edited by Matthias: topic title changed to lower case

Attached Files


Edited by Matthias, 08 April 2008 - 05:09 PM.


#2 donjoe

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Posted 09 April 2008 - 02:48 PM

[quote name='Eva Victoria' post='232783' date='8-Apr 2008, 06:01 PM']The difference between particle/inorganic/physical/non-chemical sunscreen and organic/chemical sunscreens is that particle filters (ZnO, TiO2) mirror the rays of the sun away. Rreflect the rays away from the skin back to space while chemical sunscreens filter UV rays. Chemical filters "convert" UVR into heat making them harmless for the skin.[/quote]
That's certainly consistent with the "whitening" effect (things that (re)emit more natural white light appear to be whiter), but couldn't there also be a chemical (conversion to heat) effect to these inorganic filters? I mean... look what it says here:
[quote name='http://en.wikipedia.org/wiki/Titanium_dioxide#Applications']This pigment is used extensively in plastics and other applications for its UV resistant properties where it acts as a UV absorber, efficiently transforming destructive UV light energy into heat.[/quote]



- After all, Number One, we're only mortal.
- Speak for yourself, sir. I plan to live forever.


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#3 Eva Victoria

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Posted 09 April 2008 - 03:35 PM

Sorry to say but that is not true about TiO2! It SCATTERS light. Does not absorb it!
ZnO on the other hand has some absorbing properties but it is also mainly a good UVR reflector.


The difference between particle/inorganic/physical/non-chemical sunscreen and organic/chemical sunscreens is that particle filters (ZnO, TiO2) mirror the rays of the sun away. Rreflect the rays away from the skin back to space while chemical sunscreens filter UV rays. Chemical filters "convert" UVR into heat making them harmless for the skin.

That's certainly consistent with the "whitening" effect (things that (re)emit more natural white light appear to be whiter), but couldn't there also be a chemical (conversion to heat) effect to these inorganic filters? I mean... look what it says here:

- After all, Number One, we're only mortal.
- Speak for yourself, sir. I plan to live forever.
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