How Protected Are You Against The Sun?

Joey Dekoski

Revised By: Phoebe Stinson

Overview

• What is sunscreen used for

• How sunscreen works

• Problems

• Solutions

• Why is it used?– To protect the skin of the human body from

UV radiation.

• Effects of UV light– Short term

• Sunburn

– Long term• Thickening• Wrinkling• Cancer• Cataracts

UV light• 3 types given off by the sun

1. UVC – 100 – 290 nm– Absorbed by the ozone and doesn’t affect the skin

2. UVB– 290 – 320 nm– Affects the outer layer of the skin and is the primary cause

of sunburn.– Most intense between 10-2 and during the summer

months.

3. UVA– 320 – 400 nm– Penetrates deeper into the skin and the intensity is more

constant than UVB without variations through the day and year.

UV Index

• Model that relates ozone levels to UV radiation on the ground, forecasted cloud amounts, and the elevation of the forecast cities

• Factors Affecting:1. Measurements of current total ozone amounts for

the entire globe

2. Amount of UV radiation reaching the ground

3. How human skin responds to UV wavelengths.

4. Actual incoming radiation level

5. Elevation and Clouds

UV IndexExposure

CategoryIndex Number Sun Protection Messages

LOWLOW <2Wear sunglasses on bright days. In winter, reflection

off snow can nearly double UV strength. If you burn easily, cover up and use sunscreen.

MODERATEMODERATE 3-5Take precautions, such as covering up and using

sunscreen, if you will be outside.Stay in shade near midday when the sun is strongest.

HIGHHIGH 6-7

Protection against sunburn is needed.Reduce time in the sun between 11 a.m. and 4 p.m.Cover up, wear a hat and sunglasses, and use

sunscreen.

VERY HIGHVERY HIGH 8-10

Take extra precautions. Unprotected skin will be damaged and can burn quickly.

Try to avoid the sun between 11 a.m. and 4 p.m. Otherwise, seek shade, cover up, wear a hat and sunglasses, and use sunscreen.

EXTREMEEXTREME 11+

Take all precautions. Unprotected skin can burn in minutes. Beachgoers should know that white sand and other bright surfaces reflect UV and will increase UV exposure.

Avoid the sun between 11 a.m. and 4 p.m.Seek shade, cover up, wear a hat and sunglasses,

and use sunscreen.

Skin Cancer

• 3 main types1. Melanoma

– Least common – Most serious

2. Basal cell– Most common

3. Squamous cell– 2nd most common

• Basal and Squamous cell are often referred to as non-melanoma skin cancer

Damaging Effects

• Collagen Breakdown– UV radiation increases breakdown and causes

abnormal elastin accumulation.– Accumulation creates solar scars and wrinkles

develop.

• Free Radicals– Creates free radicals which damages cell function and

alters genetic material.

• Immune System– Certain chemicals are released which suppresses the

system.

How Does Sunscreen Work?

• Combination of Organic and Inorganic Ingredients– Organic: reflects or scatters UV radiation

• eg ZnO2 and TiO2

– Inorganic: absorb UV radiation and dissipate as heat

• eg OMC, oxybenzone

octyl methoxycinnamate Oxybenzone

SPF Rating

• Sun Protection Factor– Determined by the amount of light that

induces redness in sunscreen protected skin divided by the amount of light that induces redness in unprotected skin.

– Ratings vary from SPF 1 to 45 or even higher.• Example- SPF 15 would delay the onset of

sunburn from 10 minutes to 150 minutes.

SPF Rating

– Ratings for various clothing items1. Nylon Stockings - SPF 2

2. Hats - SPF 3-6

3. Summer-weight clothing - SPF 6.5

4. Sun-protective clothing - up to SPF 30

Sunscreen Concerns

• Sunscreens offer full protection against UVB, but not UVA.

• Very few sunscreen ingredients protect against UVA• Sunscreen May Actually CAUSE Cancer

– False sense of protection leads to more time in the sun

– Chemicals do not enter the actual cells

• Sunscreen reduces production of Vitamin D– True- takes 10-15 min of unprotected sun

exposure/week– Darker complexions require more time

UVB Filters

• Nine of the sixteen approved sunscreens protect against UVB.

• Five of the nine are extensively used.– Aminobenzoic Acid stains

clothing and can cause adverse reactions.

UVA Radiation

• Suppresses immune system and allows cancer cells to flourish.

• Some sunscreens can block UVA, but not effectively. – Avobenzone quickly loses potency when

applied to the skin.– Titanium dioxide and zinc oxide are difficult to

incorporate into formulations. – Sulisobenzone and dioxybenzone are difficult

to solubilize and are rarely used.

FDA Delays

• Europe has 28 approved sunscreens– Approval process is swifter

and less costly.– Treated like cosmetics.

• FDA approves sunscreens in United States– Strenuous and expensive

testing required.– Treated like drugs.

FDA Regulations

• FDA causes delay for approval of ingredients.– 4-methylbenzylidene

camphor (4-MBC) has been used in Europe for 25 years.

FDA Regulations

• FDA does not have any rules or methods to determine UVA protection.

• Europe uses Boots PLC star rating system – Measure of the ratio of UV-A to UV-B

radiation absorbed from a simulated light source

– For a five-star rating, UV-A performance must be at least 90% of its UV-B efficiency

FDA Regulations-Examples

• 3 new sunscreens waiting for approval• Bis-ethylhexyloxyphenol methoxyphenol triazine,

Tinosorb S – Oil-phase sun care formulations– Developed using chemistry from light stabilizers used in

plastics• Methylene bis-benzotriazolyltetramethylbutylphenol,

Tinosorb M – Organic molecule with performance characteristics typical

of titanium dioxide and zinc oxide – Easier to formulate with and has higher transparency – Use in aqueous dispersions – Not only acts as a water-dispersible UV absorber, but its

particles can also scatter and reflect light

FDA Regulations

• Mexoryl• Broader range of UVA protection• Patented by L’Oreal• 2 versions

1. Mexoryl SX

• soluble, photostable, absorbent, odorless, non-staining

• Approved in 1992 in Europe and 1999 in Japan

2. Mexoryl XL

• reinforces and extends the protection offered by SX

• Approved in 1999 in Europe and 2002 in Japan

• All of these have significantly better UVA filtering• All are Photostable

Photostability of Sunscreens

• Ultraviolet rays break chemical bonds in photoactive coatings, causing breakdowns of:– Polymers– Pigments

• This leads to a loss in protective properties– Absorbed radiation attacks absorbing molecules,

exciting them– Free radicals form, and uncontrolled reactions,

therefore degradation occurs

Solutions/Alternatives

• Sunscreen suppliers currently modify approved sunscreens – Ultrafine titanium dioxide sunscreen doped

with 0.7% manganese • Manganese changes the rutile pigment's electronic

structure, eliminating its potential to generate free radicals

• Manganese also makes the pigment a better UV-A filter than undoped titanium dioxide

Solutions/Alternatives– Diethyl hexyl syringylidene malonate,

stabilizer• Singlet oxygen quencher that will effectively boost

the sunscreen's photostability • Increase effectiveness of the UV-A sunscreen

avobenzone

– SPF Boosters• Styrene acrylate copolymer

– Hollow spheres refract light and thereby increase the chance that light will contact UV filters

– Boost SPF by 50 to 70%

Solutions/Alternatives

• Emulsifying wax – Blend of phosphate esters and fatty alcohol – Boost SPF values by 15 to 20%

• ‘Green’ Sunscreen– Sunscreen active ingredient can be synthesized from

ferulic acid and triglycerides (natural plant derivatives)– Transesterification of these chemicals makes

feruloylated monoacyl and diacylglycerols when catalyzed with immobilized lipase

Green Sunscreen Process

References

• http://www.aad.org/ • http://www.epa.gov• Dermatology Times Cleveland:Sep 2004.  Vol.

25,  Iss. 9,  p. 1,19,23 (3 pp.)• U.S. News & World Report Washington:Jul 21,

2003.  Vol. 135,  Iss. 2,  p. 51 • http://pubs.acs.org/email/cen/html041305110617

.html

• http://pubs.acs.org/email/cen/html041305110308.html

• http://www.fda.gov

References-Revised

• http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=142206

• http://health.ivillage.com/everdayprobs/sunburn/0,,bw_9dh2qbx9-5,00.html

• http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=b302384b&JournalCode=GC

• http://www.dermatologytimes.com/dermatologytimes/article/articleDetail.jsp?id=169626

• http://www.patentstorm.us/patents/6926887-description.html