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| Shelter Physical Sunscreen |
From my research on the risks of sunscreens and are sunscreens safe, I had to dig deep to find the information contained in this blog. There is not a lot of information readily available on the uncertainties on the safety of using chemical sunscreens. As more and more studies are performed more information will come to light, but in the mean time I hope the information below will allow you to make your own decision whether or not you choose to use physical block or chemical sunscreens.
About 10 years ago I would only wear a chemical sunscreen if I was going to the beach, and on a daily basis I would wear a physical block sunscreen. Now, I am not a big fan of the beach, I prefer a lake! Strange but true .....and I will only go for a swim in the early or later parts of the day.
So I wear physical sunscreens only, and I choose not to sit or lay in the sun on the beautiful sunny days that we get here in Australia. I have become more sun conscious; I find myself a tree with lots of shade and wear loose clothing to cover my shoulders etc. I do however enjoy the early and later part of the day sun ensuring my vitamin D levels are maintained.
So what is the difference between chemical and physical sunscreens and what are the ingredients in sunscreens?
Chemical Sunscreens:
Are chemical UV filters that Absorb UVA and UVB rays from the Sun. Are waterproof.
Eg. Avobenzone, Oxybenzone, octyl-methoxycinnamate, benzophenone, octyldimethyl-
p-aminobenzoic acid (also called organic chemicals)
p-aminobenzoic acid (also called organic chemicals)
Cannot dissipate the energy created as efficiently as melanin and therefore the
penetration of sunscreen ingredients into the lower layers of the skin
increases the amount of free radicals present.
Some sunscreen chemicals produce potentially harmful substances if they are illuminated while in contact with living cells.The amount of sunscreen that penetrates through the stratum corneum may be large enough to cause damage. In one study of sunscreens, the authors write:1.
"The question whether UV filters acts on or in the skin has so far not been fully answered. Despite the fact that an answer would be a key to improve formulations of sun protection products, many publications carefully avoid addressing this question."
Physical Sunscreens:
Either block or reflect the UVA/UVB rays from the Sun. Inert fillers which helps protect against UV rays via light scattering
and physically blocking the light pathway into the dermal layers. Not always waterproof.
Eg, Titanium dioxide, zinc oxide (also called inorganic particles)
The FDA has approved the use of many of the chemical ingredients in sunscreens without any testing done on the safety to the human body. 1.
Sunscreen Chemicals are highly lipophilic and therefore can
be expected to bioaccumulate in the environment. In 1991 and 1993, six different
UV screens were identified in fish of the Meerfelder Maar lake (Eifel, Germany)
at total concentrations of 2 mg/kg lipid in perch (summer 1991) and 0.5 mg/kg
lipid in roach (1993). Both fish species were contaminated with sunscreens,
polychlorinated biphenyls and DDT at comparable levels. From these results it
appeared that UV screens are relevant environmental contaminants. 3.
Humans can be exposed to UV screens by dermal absorption or through the food chain. The UV screen benzophenone-3 (Bp-3) and its metabolite
2,4-dihydroxybenzophenone have been detected in human urine from 4 hr after
application of commercially available sunscreen products to the skin. 3.
UVA: penetrates deeply into the skin and can lead to cancer and premature skin ageing (400-320nm). Gives a quick tan that lasts for days by oxidizing melanin that was
already present and triggers the release of the melanin (pigment) from melanocytes (pigment cells)
UVB: is involved in tanning and burning of your skin.(320-290nm). Yields a tan that takes roughly two days to develop because it stimulates the body to produce more melanin.
UVC: is completely absorbed by the earth's atmosphere. (290-100nm)
Medical organizations such as the American Cancer Society recommend the use of sunscreen because it prevents the squamous cell carcinoma and the basal cell carcinoma. However, the use of sunscreens is controversial for various reasons. Many sunscreens do not block UVA radiation, which does not cause sunburn but can increase the rate of melanoma, another kind of skin cancer and photodermatitis, so people using sunscreens may be exposed to high UVA levels without realizing it.The use of broad-spectrum (UVA/UVB) sunscreens can address this concern. 1
Depending on the individuals skin the melanin (brown pigment) will increase with exposure to UVA/UVB this is what gives us our tan. The purpose of melanin is to absorb UV radiation and dissipate the
energy as harmless heat, blocking the UV from damaging skin tissue.
Studies:
Octyl
methoxycinnamate is a key ingredient in chemical sunscreens and is noted as being highly irritating to the skin. I wanted to delve into this ingredient more.
"Topical octyl-methoxycinnamate is absorbed by the body, as indicated in a
study conducted by the Bispebjerg Hospital in Copenhagen and published in the
July 2004 issue of the Journal of Investigative Dermatology. When used
topically for two weeks, octyl-methoxycinnamate was detectable in urine."2.
"Octyl-methoxycinnamate increased
proliferation of breast cancer cells
during a study conducted by the University of Zurich in Switzerland and published in the March 2001 issue of Environmental Health Perspectives." 2.
during a study conducted by the University of Zurich in Switzerland and published in the March 2001 issue of Environmental Health Perspectives." 2.
"The Zurich study also found evidence
of estrogenic (hormonal) activity associated with octyl-methoxycinnamate, along with
increases in uterine weight in rats. The Bispebjerg Hospital study noted minor
differences in testosterone levels associated with octyl-methoxycinnamate use." 2.
So
the jury is still out and I imagine we will not know the full truth of
the effects of chemical sunscreens for many years to come. If you are a
swimmer, then there really is no other option as most physical block
sunscreens will come off when in water. There is however guidelines
given by the FDA that babies under the age of 6 months are not to be
exposed to chemical sunscreens as their bodies are not developed enough
to be able to rid their little bodies of these harmful chemicals. When I
go swimming, instead of using a chemical sunscreen I use the Jane
Iredale Mineral Makeup (just a sheer coat of the loose powder) as this
has 20spf and they have done studies that show the spf rating lasts up
to 1 hour and 20 minutes when in the water. So I choose to wear a little
of this make up, then when I come out of the water I apply the Osmosis
Shelter which is a 100% physical block.
Happy Skin Days,
Sarah Wilkinson
Skin Matrix
References:
I also really like AVENE 30 spf very sensitive sun screen (physical block) for the face, and I would NEVER use a chemical sunscreen myself (being a health researcher and an aesthetician). Nice to see you covering the topic!
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