Sunscreen's Effects on UV Attenuation Chase McCorkle 9 th grade Central Catholic High School.
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Transcript of Sunscreen's Effects on UV Attenuation Chase McCorkle 9 th grade Central Catholic High School.
Sunscreen's Effects on UV Attenuation
Chase McCorkle 9th grade Central Catholic High School
Ultraviolet Light• Electromagnetic radiation
• The wavelength is shorter than that of visible light
• The shorter wavelength has greater energy
• The sun produces UV light
• Responsible for sunburn and some cancers
• Alters and damages DNA
• Three types; UVA, UVB, UVC
Sunscreen
• Commonly used topical ointment for help to prevent sunburn
• Prevents sunburn by reflecting or absorbing ultraviolet radiation from the sun
• Uses organic particulates to reflect or scatter UV light
Sunscreen (continued)
• Non-mineral sunscreen uses harmful ingredients
• Mineral sunscreen uses environmentally safe ingredients
• Sun protection factor (SPF) – the measurement of protection
Microbial Flora
• Comprised of all the microorganisms that reside in or on the human body (examples: skin, saliva, gut)
• Most species are non-pathogenic microorganisms that either have no effect on the host or offer some benefit
Skin Flora
• Comprised of all microorganisms of the human flora that live on the skin
• Trillions of bacteria live on or in the skin of an average human
• Stimulates the skin's immune system by the prevention of colonization by pathogenic microorganisms
Saccharomyces Cerevisiae Yeast
• Unicellular, eukaryotic microorganism
• 3–4 µm diameter
• The most studied cellular model in research
• Cell cycle is similar to human cells
• Comparable DNA replication, recombination, cell division and metabolism
Purpose
• To find if mineral sunscreen and non-mineral sunscreen vary significantly in the remediation of UV light’s effects on yeast cells
Hypothesis
• Null –there will be no significant effect of the sunscreen
• Alternative – Both sunscreens will have protective effect on UV exposed yeast survivorship
Materials
• 48 YEPD agar plates
• Spreader bars
• Ethanol
• Bunsen burner
• Vortex
• Saccharomyces Cerevisiae Yeast
• Mineral sunscreen SPF 60
• Non-mineral sunscreen SPF 60
• Wax paper
• 254 nanometer LabConco UV hood light with a UVC bulb 20-40 micro watts per square centimeter 0.7-0.9 micro watts per square centimeter at the working surface
• Incubator
• Tape
• Micro pipettes
• Sterile solution
• Klet spectrophotometer
Procedure1. Saccharomyces cerevisiae was grown overnight in
sterilized YEPD media
2. A sample of the overnight cultures was added to fresh media in a sterile sidearm flask
3. The culture of yeast was incubated at 30°C until a density of 50 Klett spectrophotometer units was reached. This represents a cell density of 10^7 cells per mL
4. The culture was diluted in sterile dilution fluid to a concentration of approximately 10^5 cells per mL
Procedure (continued)
5. Measured out 0.1 grams of mineral sunscreen on wax paper
6. Spread in a circular motion using a sterilized spreader bar
7. Created 16 pieces for mineral and 16 non-mineral
8. Used sterile pipette to add 0.1 mL of yeast (10^3 cells per mL) to the YEPD plate
9. Attached the wax paper covered with sunscreen as a replacement lid for the plate
Procedure (continued)
10. Attached wax paper with nothing on it to create a control
11. Exposed plates to UV light at the time of 0, 60, 120, 360, and 720 seconds
12. When finished, took off the wax paper and put on the lids
13. Incubated at 38 degrees c for 48 hours
14. Measured the survivorship by counting the colonies of yeast
15. Took plates to lab at Carnegie Mellon University to be autoclaved
Sunscreen effects on UV exposed survivorship
P-Value: 0.00039111
UV exposure (seconds)
0 60 120 360 7200
30
60
90
120
88.2
51.5
4.31.3 0.8
88.2
109
73.5
32.5
17.8
88.2
42.5
61 0
Control
Non Mineral
Mineral
Yeast
colo
nie
s
P- Values
Time 0 60 120 360 720
P-value 0 0.9657 1.19E-0.6
0.00205 0.03998
Analysis Dunnett’s TestT-Value 3.03
Time 0 Sec 60 sec 120 sec 360 sec 720 sec
Mineral T-Value
0Insignificant
1.334Insignificant
0.295Insignificant
0.035Insignificant
0.114Insignificant
Non-Mineral T-Value
0 Insignificant
8.524Significant
11.689Significant
4.449Significant
2.596Insignificant
Analysis Dunnett’s Test
T-value 3.03
Time 0 sec 60 sec 120 sec 360 sec 720 sec
Mineral T-Value
0Insignificant
9.852Significant
11.393Significant
4.485Significant
2.711Insignificant
Results• Does UV light have a significant effect on
yeast survivorship?
• Yes: P-Value 0.00039111
• Is there significant variation between mineral and non-mineral sunscreen?
• Yes: T-Crit is greater than 3.03 at 60, 120, and 360 seconds but not at 720 seconds
Conclusion• Null – UV light will not have a significant
effect on yeast survivorship
• Reject the null
• Alternative – Both sunscreens will have protective effect on UV exposed yeast survivorship
• Reject the alternative
Limitations and extensions
• Plate lids were replaced which could lead to possible contamination
• Hard to insure even spread
• Only UVC light used
• Use different brands
• Use shorter exposure time intervals
• Use other types of exposure
• Use other means of spreading
• Try different microbial model
• Test growth/help
Works cited
1. "Effects of UV Radiation on You." Student's Guide -. N.p., n.d. Web. 16 Dec. 2014.
2. HowStuffWorks. HowStuffWorks.com, n.d. Web. 20 Dec. 2014.
3. "Natural vs. Chemical Sunscreen - Goddess Garden." Goddess Garden Natural vs Chemical Sunscreen Comments. N.p., 18 Mar. 2012. Web. 03 Dec. 2014.
4. "OCTINOXATE." || Skin Deep® Cosmetics Database. N.p., n.d. Web. 10 Dec. 2014.
5. "OXYBENZONE." || Skin Deep® Cosmetics Database. N.p., n.d. Web. 11 Dec. 2014.
6. "What Is SPF Sunscreen?" - Sun Protection Factor Explained by Badger. N.p., n.d. Web. 17 Dec. 2014.
Anova (all)Anova: Single Factor
SUMMARYGroups Count Sum Average Variance
Column 1 20 615 30.75 1566.618Column 2 20 1356 67.8 1587.747Column 3 20 447 22.35 730.2395
ANOVASource of Variation SS df MS F P-value F crit
Between Groups 23393.1 2 11696.55 9.033003 0.000391 3.158843Within Groups 73807.5 57 1294.868
Total 97200.6 59