Link to original: http://sphynxcatvp.nocturna.org/health/sc-sunscreens.html
Sunscreens are a lotion, spray, gel or other topically-applied product that reflects or absorbs some of the sun's UV radiation on the skin, and helps prevent sunburn. Light skin is more susceptible to sun damage than darker skin, so people with lighter skin tones need stronger sunscreen (The melanin in darker skin affords some natural skin protection.) The higher the SPF, the more protection a sunscreen is supposed to offer against UV-B rays (typically the part of the spectrum that causes sunburn.) (You can also see the eMedicine article linked below on sunscreens and photoprotection for more information.)
This is NOT an increase in time before you burn!
It is a measure of how much UV radiation you can handle WITH the sunscreen before you burn, relative to how much you can handle WITHOUT the sunscreen. The time you have will always vary, with such factors affecting it as time of day, your latitude (how far north/south of the equator you are), whether it's winter or summer, whether you have scattered cover (in and out of wooded areas or buildings), etc.
Basic sun protection tips
- Stay in the shade, when possible, between 10am and 4pm
- Avoid tanning booths of any type
- Cover up with tight-weave clothing, including a broad-brimmed hat and UV-blocking sunglasses
- Apply 1 ounce (apx 2 tablespoons) of sunscreen/sunblock to body 15-30 minutes before going outside
- Reapply 15-30 minutes after exposure
- Reapply again after activity involving things such as swimming, sweating, toweling off, and vigorous rubbing.
UV rays are classified into at least three different groupings, depending on the size of the wavelength. These are:
- UV-C: 200 - 290 nanometers (Commonly given off by welding equipment)
- UV-B: 290 - 320 nanometers
- UV-A: 340 - 400 nanometers (UV-A 1, or "long" UV-A)
- UV-A: 320 - 340 nanometers (UV-A 2, or "short" UV-A)
The UV-A / UV-B wavelengths are the ones commonly referred to on packages of sunscreen lotion (and now you know the wavelengths!) but UV-C should be kept in mind as a factor as well - especially with exposure to sunlight and high-UV generating light sources - even if it's not as commonly understood. UV-C is typically given off by various types of welding equipment, so those of you who may be welding for a living, or know someone who is, will already understand to take this into account.
UV-B is particularly effective at damaging DNA, and is a cause of melanoma and other types of skin cancer. As the ozone layer is depleted, this effect will become worse over time (shortening the time it's safe to be in the sun too, incidentally.)
Sunscreen or sunblock?
It is important to understand the difference in terms - while they are often used interchangeably, they really should NOT be, as they are describing two different methods of sun protection.
"Sunscreens" absorb UV light so that it (theoretically) does not reach your skin.
"Sunblocks" will physically reflect the suns rays without absorption. (In practical terms, the difference you FEEL will likely be that the pure sunblocks will make your skin feel cooler when exposed to sunlight than the chemical sunscreens do - above and beyond any reaction or lack of reaction to the ingredients.)
- Sunblocks - Inorganic particulate UV-A and UV-B blockers:
- Titanium Dioxide, Zinc Oxide
- Sunscreens - Chemical compounds - example UV-A Absorbers:
- 4-Aminobenzoic acid / PABA, Bisdisulizole disodium (Neo Heliopan AP), and others
- Sunscreens - Chemical compounds - example UV-B Absorbers:
- 4-Aminobenzoic acid / PABA, Homosalate, Octyl salicylate / Octisalate, Phenylbenzimidazole sulfonic acid / Ensulizole and others.
- Sunscreens - Chemical compounds - Example UV-A and UV-B Absorbers:
- Benzophenone 112, Octocrylene, Oxybenzone / Eusolex 4360 (derivitive of Benzophenone), Sulisobenzone, and others.
Anything that blocks UV-A and UV-B is considered to be "broad spectrum" in most descriptions.
What's the big deal?
Some people find the sunscreen chemicals to be irritating to one degree or another, such as a rash or massive itching, and do not tolerate them on the skin for long at all. Also, there are recent studies coming out showing that these chemicals may do more harm than good in the long term, causing skin damage (doi:10.1016/j.freeradbiomed.2006.06.011 - see "Free Radical Biology & Medicine" link below), DNA or internal organ changes because they're absorbed through the skin (doi:10.1289/ehp.11269 - see "EHP" link below), cancer (doi:10.1016/0014-5793(93)80141-G - see "FEBS Letters" link below), and so on. Most chemical sunscreens have between 3-7 of the available sunscreen ingredients in an attempt to provide a broad-spectrum, higher protection rating.
Patients with photodermatitis, eczema, or other skin conditions where the external layers are compromised need to be aware that chemical based sunscreens MAY aggravate the existing conditions, or provide new and even more annoying symptoms to deal with. Rashes that some people experience MAY be a simple allergic reaction OR may be a photocontact (only on exposure to UV radiation) reaction instead.
On the sunblock end of things, there is some debate as to whether the microfine/nanosized particulates for Titanium Dioxide [TiO(2)] manage to get absorbed into the skin and cause damage. There are studies such as a toxicology study (doi:10.1016/j.tiv.2005.08.008 - see "Toxicology in Vitro" below) that was unable to prove this using pig skin (pig is often used as a human replacement in more dangerous experiments) - but also other studies (Australas J Dermatol. 1996 Nov;37(4):185-7 - see "Pubmed - pilot study" link below) showing evidence of penetration into the epidermis and dermis layers of the skin. At the moment there doesn't seem to be a definitive consensus, bear this in mind while you decide for yourself.
Whether microfine or not, zinc oxide seems to be both safe and UV-stable in my research results. If you can find a sunblock with ONLY zinc oxide, it appears to be the best choice with least side effects or problems. (See "Pubmed: Microfine zinc oxide" links below.)
Zinc Oxide is showing the least amount of reactivity issues in my research, so if you normally have problems with sunscreens, or are concerned about long-term effects, I would recommend a zinc-only sunscreen - and adequate additional protection - to be safe. My research is showing that a sunblock with only Zinc Oxide is unlikely to get over an SPF of 10 without additional chemical compounds, so additional protection WILL be required, especially if you'll be outdoors for long periods of time.
READ THE FINE PRINT ON LABELS!
Some sunscreens advertising themselves as "Zinc Oxide" with a medium to high SPF, but ALSO also contain between 2-5 of the chemical compounds in addition to the zinc oxide.
Recommended sunscreen brands and types (June 2010)
Interestingly, the "high SPF" sunscreens (70+, etc.) are NOT necessarily the best ones, at least in my experience. These are typically the chemical compound based sunscreens, and may or may not be mixed with titanium dioxide.
The inorganic particulates alone typically result in an average SPF of 30ish, but give me the most effective sun protection with the least amount of problems. You will have better luck locally finding many of these particulate-only sunblocks in stores that specialize in organic products, or that have a specific section for organic products.
Here is a list of particulate-only sunscreens that I can find this year (2010) by brand, then type. This list was compiled by combing the drugstore.com website, but many of these are also available via amazon as well as your local retailers. Unless otherwise noted, items in this list have a combination of both Titanium Dioxide and Zinc Oxide as their only active ingredients:
- All Terrain KidSport 15 (Zinc Oxide only; microparticle)
- All Terrain KidSport 30 (Zinc Oxide only; microparticle)
- All Terrain TerraSport 15 (Zinc Oxide only; microparticle)
- All Terrain TerraSport 30 (Zinc Oxide only; microparticle)
- All Terrain AquaSport 15 (Zinc Oxide only; microparticle)
- All Terrain AquaSport 30 (Zinc Oxide only; microparticle)
- Avalon Organics: aby Natural Mineral Sunscreen SPF 18 (Titanium Dioxide only)
- Badger: All Natural Sunscreen, SPF 15 (Zinc Oxide only)
- Badger: All Natural Sunscreen, SPF 30 (Zinc Oxide only)
- Blue Lizard: Australian Sunscreen, Sensitive, SPF 30+ (available by the gallon!)
- Burt's Bees: Chemical Free Radiance SPF 15 Day Lotion
- Burt's Bees: Chemical Free Sun Screen SPF 30 (Titanium Dioxide only)
- California Baby: SPF 30+ Sunblock Stick (microparticle Titanium Dioxide)
- California Baby: Water Resistant, Hypo-Allergenic Sunscreen, SPF 30+ (microparticle Titanium Dioxide)
- California Baby: SPF 18 Moisturizing Sunscreen, No Fragrence (Titanium Dioxide only)
- Cotz: Face Cotz, Sensitive Skin Sunscreen, SPF 40 (microparticle Titanium Dioxide and Zinc Oxide)
- Cotz Sunscreen, Water Resistant SPF 58 (microparticle Titanium Dioxide and Zinc Oxide)
- Kiss My Face: Non-Chemical Sunscreen Lotion, SPF 18
- MyChelle Dermaceuticals: Sun Shield SPF 28
- Neutrogena: Pure & Free Baby Sunblock Stick, SPF 60+
- Neutrogena: Sensitive Skin Sunblock Lotion, SPF 30 (Titanium Dioxide only)
- Neutrogena: Sensitive Skin Sunblock Lotion, SPF 60+
- Nia24: Sun Damage Prevention 100% Mineral Sunscreen (microparticle Titanium Dioxide and Zinc Oxide)
- Ocean Potion Suncare: Natural Mineral Sunblock, Active Wear SPF 30
- Ocean Potion Suncare: Natural Mineral Protective Lotion, Faces SPF 45
- Ocean Potion Suncare: Natural Mineral Sunblock, Kids SPF 45
- Ocean Potion Suncare: Natural Daily SPF 30
- J/A/S/O/N Natural Cosmetics: Sunbrella MINERAL Natural Sunblock, SPF 30+
- J/A/S/O/N Natural Cosmetics: Earth's Best Organic Sunblock, Chemical Free SPF 30+
- Little Twig: Non Chemical Sunscreen 30+ (microparticle Titanium Dioxide and Zinc Oxide)
- Nature's Gate: Mineral Kidsblock SPF 20
- Nature's Gate: Mineral Sunblock SPF 20
- UV Natural: Baby Sunscreen SPF 30+ [Australia] (Zinc Oxide only)
- UV Natural: Sport Sunscreen SPF 30+ [Australia] (Zinc Oxide only)
- UV Natural: Sunscreen SPF 30+ [Australia] (Zinc Oxide only)
- Vanicream Sunscreen: Sensitive Skin, SPF 30
** If any of these are not available, try any brand of diaper rash ointment - at least in the USA, it's zinc oxide only. **
Avoid any sunscreens with any of these phrases on the label:
- "Continuous Spray" (particulates don't spray well in a pressurized sprayer)
- "Dark tanning" (won't ever have particulates since they block both UV-A and UV-B, and UV-B promotes tanning)
- "Dry touch"
- "Fast Absorbing"
- "Oil Free"
- "Ultra Sheer"
- "Ultra Light"
...or any similar phrases - these are going to have either just the chemical compounds in them, or the particulates will be mixed with the chemical compounds, and anyone sensitive to the chemicals will STILL have a problem even though the particulates are also in it.
Making your own (in a pinch)
- 1.5 oz Sunblocking agent - zinc oxide recommended - available online
- 8 oz of carrier: lotion, oil, etc. - your choice
- 1oz emulsifing wax (what is emulsifying wax?)
- 1 mixing container (bowl, etc.)
- 1 clean storage container to put all this in when done
** Wear gloves and facemask at all time to avoid inhaling dust **
- Heat the wax until it melts
- Add the carrier lotion, mix thoroughly
- Add the sunblocking agent
- Blend thoroughly, scraping down container sides
- Spend still more time blending thoroughly (You want this to actually be effective!)
- Put into jar for use
** Remember this has no preservatives, so only make small batches you'll use in a couple months **
- eMedicine: Sunscreens and Photoprotection
- EHP: Concentrations of...Benzophenone-3 in residents of the USA...
- FEBS Letters: Sunlight-induced mutagenicy of a common sunscreen ingredient
- Free Radical Biology & Medicine: Sunscreen Enhancement of UV-Induced ROS...
- FDA.gov: Sun Protection Factor
- PubMed: Cellular toxicity of TiO(2) nanoparticles in Anatase and Rutile phase
- PubMed: Microfine zinc oxide (Z-cote) as a photostable UVA/UVB sunblock agent
- PubMed: Microfine zinc oxide is a superior sunscreen...to microfine titanium dioxide
- PubMed: Mineral filters in sunscreen products
- PubMed: Pilot study on the percutaneous absorption of microfine TiO(2) from sunscreens
- PubMed: Relation between SPF and and amount of sunscreen applied
- PubMed: Sunscreen enhancement of UV-induced reactive oxygen species in the skin
- PubMed: When should sunscreen be reapplied?
- Toxicology in Vitro: ...absorption of microfine zinc oxide and titanium dioxide...