05.27.08

Sunlight and Cancer

Posted in Facts About UV Protection at 8:53 pm by Administrator

We’ve talked a lot about the different wave-lengths of UV light, in particular UVA and UVB and how they affect the skin: UVB=burning, UVA=aging.

The discussion hasn’t touched on UVC for two reasons; 1) UVC rays are prevented from reaching the earth by the ozone layer, for the most part, and 2) I don’t want to be the one to sound alarm bells. However, so much misinformation abounds surrounding the complicated topic of sun protection that I feel I must take up the torch once again. This time the discussion will be around UV light and its relationship to skin cancer.

UVB: The UVB rays are the burning rays. They:

• Penetrate the epidermis
• Are present from 10AM to 4 PM
• Reflect off shiny surfaces
• are linked to squamous and basal cell carcinomas, damage DNA
• are 1000x stronger than UVA
• stimulate melanin biosynthesis and keratinocyte production

UVA: The long wavelength, low energy UVA rays are the aging rays. They:

• penetrate glass and clouds, penetrate to the dermis (Only 10% of UVB rays reach the dermis, about 50% of UVA rays do)
• present from sun up to sundown
• cross-link collagen and elastin
• damage DNA, carcinogenic (though the least associated with skin cancer)
• destroy langerhans cells and immune function
• turn melanin darker
• 1000x more prevalent than UVB
• cause hyper-hypo-pigmentation and broken capillaries

UVC: The short wavelength, high energy UVC rays. They are:

• the most carcinogenic
• sterilizing rays used to kill small organisms
• mostly absorbed by the ozone layer, sunscreens provide NO protection

Skin cancer facts

When it comes to skin cancer, we know that more than 90% are the result of sun exposure, with over 1 million new cases being reported each year. One of three fair-skinned people will develop a skin cancer, and one out of five of the general population will do the same. However, while the link between the UVB rays (and to a lesser extent UVA rays) and squamous and basal cell carcinomas has been established, the link between deadly melanomas and sun exposure is less sure. Knowing the facts will help you make an informed choice about the degree of protection you want for yourself. Here are some things to look at before coming to a decision:

Cosmetic

If you want to avoid premature wrinkling or sunspots use full-spectrum UVA/UVB protection. Recommended: Zinc oxide at 20% concentration.

If you don’t care about any of these issues (and many men I have encountered fall in this category though few women, what a surprise) then wear a hat to protect your bald spot and put sunblock on your nose at the beach to protect against basal cell lesions and you’ll probably be fine.

Safety

Squamous and basal cell carcinoma risks are reduced with full-spectrum UVA/UVB protection. Zinc oxide at 20% concentration is your best protection. At least be aware of UVC risks, and if you are in Australia limit your sun exposure. During peak burning hours ANYWHERE where burning is a problem, at high altitudes, at the beach, in the water or skiing, you are better off to stay in the shade as much as possible.

Children

Children are looking at 100 years of sun exposure, and these days also at 100 years of exposure to ingredients in sunscreens. You have to balance for yourself which is ultimately more lethal. But here is my take on it.

For the first five years you can depend on a child’s natural protection to do the job for the most part. At the beach wear hats, clothing and slather them with diaper cream or 20% zinc oxide from a safe product. At other times, and if your child burns easily, look at using Vitamin C directly on the skin. Wet it with green tea to get more natural protection. Overture also contains astaxanthin to protect against burning naturally. Neither of these will interfere with Vitamin D synthesis. My recommendations for children 5 and under:
1) Vitamin C
2) Astaxanthin
3) For serious sun, zinc oxide from diaper rash cream or Sun Serum

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