Transcript UVB light - MathScience Innovation Center

From SPF to SNF
(Sunscreen Nano Facts)
Cathleen Burke (Chesterfield Technical Center)
Karen Trickett (Atlee High School, Hanover Co.)
MathScience Innovation Center
Nanotechnology Fellows
http://all-free-download.com/images/graphiclarge/decorative_sun_clip_art_23259.jpg
Part 1:
The Energy of Light
The Sun
www.dreamstime.com
The sun’s electromagnetic spectrum consists
of seven types of radiation with different
quantities of energy and differing wavelengths
including:
Radiowaves
Microwaves
Infrared waves
Visible light
Ultraviolet rays
X-rays
Gamma rays
The Electromagnetic Spectrum
www.dnr.sc.gov
Ultraviolet Light
www.abstract.desktopnexus.com
•Includes wavelengths between 380 and
10 nm
•Can not be visualized by the human eye
•Can be absorbed by skin cells and the
energy from them can damage DNA in the
cells which absorb them
Types of UV light
•UVC light
Filtered out by the atmosphere
•UVB light
Absorbed by the upper epidermis
•UVA light
Absorbed into the lower layers of the
epidermis as well as the dermis
www.ewg.org
Is all UV light Bad??
No!
Small amounts of UV light are
needed for strong bones and good
health!
www.homeschooling.gomilpitas.com/explore/skeleton.htm
So what is the problem with UV light?
Increasing amounts of UVA and UVB
light are reaching the surface of the
Earth due to the destruction of the
stratospheric ozone layer
Absorbed UVB light causes sunburns
www.yaflamingalah.wordpress.com
Absorbed UVA light penetrates deep into the
epidermis where cells called melanocytes are
found. This triggers the melanocytes to produce the
pigment melanin which results in a tan.
www.lab.anhb.uwa.edu.au
Many people think suntans give you a
healthy appearance
but those tanning rays are actually causing
damage to skin, leading to:
•Premature wrinkles
•cataracts
www.sheknows.com
www.teslaowner.wordpress.com
http://newsimg.bbc.co.uk/media/images/4571
0000/jpg/_45710149__42953099_wrinkles_c
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•Changes to DNA that can lead to skin cancer
Types of Skin Cancers
Malignant
melanoma
the- most
serious
Basal
cell carcinoma
- -appears
on appears
the
Squamous
cell carcinoma
also
type the
of
skin
from due
deeper
upper
layers
ofcancer.
thelayers
skinResults
due
overexposure
on
upper
ofto skin
to
penetrating
UVA
to
UVB rays to
overexposure
UVB rays
rays which damage
melanocytes.
http://www.trihealth.com/ser/cancer/images/scc01_lg.jpg
www.teslaowner.wordpress.com
http://www.laserdermatologynyc.com/images/text/skin-cancer/basal-cell-carcinoma.jpg
Sun Protection
Sunblocks and sunscreens
are used to protect against
the sun’s damaging rays.
The active ingredients in
sunscreens either absorb,
block or scatter UV rays
www.shutterstock.com
Sunscreens
www.bychancewordpress.com
www.bychancewordpress.com
•17 active ingredients are currently approved
for use in sunscreens in the U.S
• 2 categories of active ingredients:
1) inorganic minerals– zinc oxide (ZnO) and
titanium dioxide (TiO2)
2)Organic chemicals – are padimate O,
oxybenzone, and methoxycinnamate
In the past, most available sunscreens
have protected against UVB (burning)
rays with mixtures of up to 3 chemicals
that block various UVB wavelengths
Recently, broad spectrum
sunscreens have become
available which add UVA
protection by adding
Oxybenzone or avobenzone
http://blogs.nature.com/nm/spoonful/sunscreen.jpg
Sun Protection Factor (SPF)
Measures the length of time skin is protected
against exposure to UVB light.
Higher SPF’s protect
against burning longer.
www.shutterstock.com
SPF’s vary from as low as 2 to over 100.
Sunblocks with ZnO and TiO2 protect against the
entire range of UV wavelengths without the use of
chemicals.
So, why don’t more people use them?
http://images.travelpod.com/users/ejdonohu/1.1246005663.sunscreen-happy.jpg
The solution:
Nanotechnology!!
http://www.enviroblog.org/nanotechnology-softech.gif
Nanotechnology is a relatively new science which
involves the creation of products that contain
nano-sized materials in the range of 1 – 100
nanometers.
At these tiny sizes, many particles often exhibit
unique chemical, physical and biological properties
that are different from larger particles of the same
type.
How small is a nanometer?
A nanometer (nm) is a billionth
of a meter
Compare this to some objects you
may be familiar with:
•Thickness of a sheet of paper = 100,000 nm
•A red blood cell = 6,000 nm wide
•Width of a single DNA molecule or a cell
membrane = 3 nm
www.apfmalte.com
To change the usual opaque white color of
sunblocks with zinc and titanium oxides, the
particle size of these 2 minerals has been reduced
to nanosize – 5 to 20 nm!
As nanoparticles, both zinc oxide and titanium
dioxide are transparent.
http://i.ehow.com/images/a04/l7/tj/apply-sunscreen-face-200X200.jpg
Sunscreen manufacturers have been
using nanosized TiO2 since 1990 and
nanosized ZnO since 1999.
Today over 300 sunscreens
on the market contain
nanosized mineral particles
www.action.foe.org
Part 2:
Risks vs. Benefits
Controversy Concerning Nano Sunscreens
Some concerns about sunscreens containing
nanoparticles include:
1) Safety concerns regarding nanosized particles
2) Lack of labeling requirements which inform
consumers that the product they are using
contains nanoparticles.
Microsoft clipart
Safety Concerns
Nanosized ZnO and TiO2 particles may be
small enough to be absorbed into the lower
layers of living skin cells where they may be
activated by light to react in a way which is
unsafe for living tissue.
Nano-sized particles, due to their small size,
are more reactive than their full-sized
counterparts.
www.stu.westga.edu
These nanoparticles, upon absorbing UV light,
have been shown to emit free radicals which
can cause damage to biomolecules such as
DNA inside cells.
While only a small amount of data is available on the
safety of nanoparticles in sunscreen, the weight of
current data seems to suggest that these particles do
NOT get absorbed into healthy skin when applied in
lotion form.
http://farm3.static.flickr.com/2474/3772444566_550409bcb1.jpg
More research needs to be done to definitively
address this safety concern.
Additional Safety Concerns
Nanoparticles may wash off sunbathers’ skin
and enter the environment
http://www.skaneatelessuites.com/wp-content/uploads/2008/07/lake_swimming.jpg
Both zinc and titanium are known to
have strong antibacterial properties
www.scottcamazine.com
A study published in Scientific American (March
2009)concluded that nanosized TiO2 particles
substantially affect the cell wall of E. coli bacteria in
very small quantities(10 – 100 mg/L) after less than
24 hours of exposure.
www.sciencecodex.com/titanium_dioxide _nanoparticles
This micrograph displays visually the results
of this study.
In another study conducted at Utah State
University and the University of Utah, beneficial
soil bacteria were shown to be damaged by Silver,
Copper Oxide and Zinc Oxide particles even at low
levels of exposure.
www.reuserinc.com/images/nitroDust.jpg
Since concerns about these sunscreens haven’t
been fully addressed, many feel that labeling of
sunscreens that contain nanoparticles should be
mandatory.
http://
www.sxc.hu/pic/m/r/re/resignent/1023097_warning_icon_26.jpg
What do you think??
http://media.rd.com/rd/images/rdc/slideshows/healthy-changes-for-new-year/healthy-changes-sunscreen-03-ss.jpg
References:
Tanning
http://kidshealthorg/teen/safety/safebasics/tanning.html#
TGA Fact Sheet – Sunscreens
http://www.tga.gov.au/npmeds/sunscreen-zotd.htm
Sunscreens/Sunblocks. American Academy of Dermatology
http://www.aad.org/public/publications/pamphlets/sun_sunscreens.html
“Nanoparticles in Sunscreen Damage Microbes”. Cimitile, Matthew.
Scientific American. March 24,2009.
Tanning: Is it Safe?
www.csulb.edu/divisions/students/nrc/health_topics/TanningIsitSafe.htm
Sunscreen
www.skincancer.org/sunscreensExplained.html