Re: Topical Sun Protectives

From: acard (acard_at_dev.net)
Date: 09/20/04 

Date: Mon, 20 Sep 2004 01:28:57 GMT

poise wrote:
> Furthermore, protecting against UVB while employing faulty UVA filtering
> techniques is actually worse than wearing no sunscreen at all, not only
> because it encourages more sun exposure, and not only because carcinogenic
> (pro-radical) compounds are generally utilized, but perhaps most directly
> because it cuts off the body's natural production of protective melanin,
> which is dependent upon UVB.

Not true. Some protection is better than none.

See:

Arch Dermatol. 2004 Jun;140(6):745-6.
The end of the sunscreen and melanoma controversy?
Bigby ME.
PMID: 15210469 [PubMed - indexed for MEDLINE]

J Drugs Dermatol. 2004 May-Jun;3(3):323-4.
Does sunscreen cause melanoma? Researchers now strongly say no.
[No authors listed]
PMID: 15176171 [PubMed - indexed for MEDLINE]

Ann Intern Med. 2003 Dec 16;139(12):966-78.
Sunscreen use and the risk for melanoma: a quantitative review.
Dennis LK, Beane Freeman LE, VanBeek MJ.
PMID: 14678916 [PubMed - indexed for MEDLINE]

>>Most of the daily sun protectants people use are made of microionized zinc
>>or titanium, which are quite useless, in my opinion, against the
>>ever-important UVA rays.

They are very inefficient protectors--even a very high concentration
does not provide much UVA protection.

>>Avobenzone (parsol 1789), like topical PABA,
>>converts UV to free radicals, which is obviously not good.

So do physical screens, particularly in the UVA range and when
the particles are not coated with silicone or some other similar
substance, but both are orders of magnitude less damaging than UV
radiation striking bare skin.

>> If you use this
>>ingredient for your UVA protection, it should be in a rich antioxidant
>
> base,

and combined with other UVA screens

>>and reapplied each sunshine hour (it breaks down quickly).

and combined with stability enhancers. Many Cosmair formulations
employing avobenzone are quite photostable.

It is incorrect to state that avobenzone is not photostable.
Stability of avobenzone depends on the formulation.

>>Further, there
>
> is
>
>>some concern that the daily use of chemical screens (especially the
>>Benzophenones) may pose a real systemic risk.

There is some concern but no real evidence. The smaller, oil-soluble
filters are more likely to be systemically absorbed.

>>
>> Mexoryl is a brilliant
>>innovation.

There are two: Mexory SX and Mexoryl XL. There are also two Tinosorbs
(S amd M) as well as a few other chemical UVA filters on the horizon.
None of these are currently FDA approved.

>>It should be noted that, as well as being poor UVA protectants,
>>microniozed/encapsulated physical blocks are effectively absorbed by the
>>skin. We know that this poses a free radical risk, but conclusive in vivo
>>study is sparse at this point.

The sunscreens most effective in blocking and/or reflecting UVA
comtain a number of chemical AND physical UVA filters in both the
water- and oil-soluble fractions of the formulation. Some
examples: La Roche Posay Anthelios L, XL, and XL Fluide Extreme,
Bioderma Photoderm Max and Laser, and many others. Look for a very
high PPD (persistent pigment darkening) protection factor, which is
a rough guide to how protective a formulation will be in the UVA
fraction.

You can order such sunscreens from Europe, pay a small fortune in
shipping, and hope that you do get your package (up to 3 months later).
Or pay 3x retail and order them through USA websites, or write letters
to your congressmen and hope for the best.

More on what consitutes superior UVA protection:

Stege H, Budde MA, Grether-Beck S, Krutmann J.
Evaluation of the capacity of sunscreens to photoprotect lupus
erythematosus patients by employing the photoprovocation test.
Photodermatol Photoimmunol Photomed. 2000 Dec;16(6):256-9.
PMID: 11132128 [PubMed - indexed for MEDLINE]

Bernerd F, Vioux C, Lejeune F, Asselineau D.
The sun protection factor (SPF) inadequately defines broad spectrum
photoprotection: demonstration using skin reconstructed in vitro exposed
to UVA, UVBor UV-solar simulated radiation.
Eur J Dermatol. 2003 May-Jun;13(3):242-9.
PMID: 12804982 [PubMed - indexed for MEDLINE]

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