Colin M c Steen Pittsburgh Central Catholic High School Grade 9

Colin M c Steen Pittsburgh Central Catholic High School Grade 9

Products combining several chemical and physical ingredients. Help prevent ultraviolent radiation (UV rays) from reaching the skin. Can protect against UVA and UVB rays (Broad Spectrum) Chemical ingredients absorb UV rays physical ingredients deflect UV rays.

Walgreens Broad Spectrum SPF 90 Sport Sunscreen Active Ingredients: Avobenzone (3%) Octisalate (5%) Oxybenzone (6%) Octocrylene.(10%) Homosalate.(15%) Inactive Ingredients: Alcohol denat., butyloctyl salicylate, polyester-10, propylene glycol dibenzoate, acrylates/octylacrylamide copolymer, glycerin, diethylhexyl syringlidenemalonate, fragrance, caprylic/capric triglyceride

Benzophenone-3 Active in virtually every sunscreen Found in 97% of Americans urine Shown to affect the endocrine system of both men and women Only dangerous at extremely high concentrations

Effects of oxybenzone on estrogenic activity and reproduction in fish. Effects only at concentrations much higher than natural Oxybenzone irritating or sensitizing human skin Concentrations of 1-6% do not have significant effects Sunscreen Increasing Dermal Penetration Sunscreens can significantly increase or decrease dermal penetration

Present in the respiratory, urinary, and digestive tracts, as well as the skin. Consists of mostly bacteria, and few protists and fungi. Most are harmless, but some can cause diseases. Influences human anatomy, physiology, and overall health. 10 14 bacteria are harbored within and on humans.

Cell walls contain an extra layer of lipopolysaccharides for extra protection. Outer membrane protects bacteria from several antibiotics. Most pathogenic bacteria in humans are Gram (+) organisms. Simple cell wall Some antibiotics work against the formation of the cell wall.

Gram positive coccus Common surface symbiont in many mammals. Most forms considered non-pathogenic. Potentially pathogenic upon systemic entry. Forms biofilms

Rod-shaped: 2 micrometer diameter Gram negative bacteria Reproduction rate: 20 minutes Survival, growth, and replication require only a single carbon source and ammonium salts. Common symbiont found in the lower intestines of warm blooded animals. Few pathogenic: Almost 73,000 cases of infection and 61 deaths per year in the U.S. Most common prokaryote model

To examine the effects of sunscreen on the survivorship of Staph and E. coli cells.

Null: Sunscreen will not have a significant effect on the survivorship of Staph and E. coli. Alternative: Sunscreen will significantly alter the survivorship of Staph and E. coli.

Walgreens Sunscreen (6% Oxybenzone) Micropipettes + Sterile tips Spreader bars LB agar plates (1% Tryptone, 0.5% Yeast extract, 1% NaCl) Escherichia coli DH5-alpha (E. coli) (Obtained from Doonan Lab, CMU) Staphylococcus epidermidis (Staph) (Obtained from Ward s Scientific) Burner Sidearm Flask Vortex Incubator Gloves / goggles Klett Spectrophotometer SDF (Sterile Dilution Fluid) (100mM KH2PO, 100mM K2HPO4, 10mM MgSO4, 1m NaCl) Sterile Test Tubes Ethanol 0.22 micron syringe filter and 10 ml syringe

1. Bacteria (Staph and E. coli) were grown overnight in sterile LB Media. 2. Samples of the overnight cultures were added to fresh media in a sterile sidearm flask. 3. The cultures were placed in an incubator (37 C) until a density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately 10 8 cells/ml. 4. The cultures were diluted in sterile dilution fluid to a concentration of approximately 10 5 cells/ml. 5. The sunscreen was sterile filtered.

6. Sunscreen was mixed with the appropriate amounts of SDF to create concentrations of 0%, 0.01%, 0.1%, and 1%. Concentration Chart 0% 0.01% 0.1% 1% Sterile Dilution Fluid 9.9 ml 9.899 ml 9.89 ml 9.8 ml Microbe 0.1 ml 0.1 ml 0.1 ml 0.1 ml Sunscreen 0 ml 0.001 ml 0.01 ml 0.1 ml Total Volume 10 ml 10 ml 10 ml 10 ml 7. 100 µl (.1 ml) of cell culture was then added to solutions, yielding a final volume of 10 ml and a cell density of approximately 10 3 cells/ml.

8. The solutions were mixed by vortexing and allowed to sit at room temperature for 5 minutes. 9. After vortexing to evenly suspend cells, 100 µl (.1 ml) aliquots were removed from the tubes and spread on LB agar plates. 10. The plates were incubated at 37 C overnight 11. The resulting colonies were counted visually, assuming each colony arose from one cell. 12. Stat tests were completed.

# of Colonies 400 360 320 280 240 200 160 120 80 40 0 Average Number of Colonies / Concentration 0% 0.01% 0.10% 1% Concentration of Sunscreen P-Value=.081442

# of Colonies 250 225 200 175 150 125 100 75 50 25 0 Average Number of Colonies / Concentration 0% 0.01% 0.10% 1% Concentration of Sunscreen P-Value=.178454

The null hypothesis cannot be rejected for Staph or E. coli. Both P-Values were higher than.05 No evidence to support any negative effects of sunscreen.

Plating slightly unsynchronized Only 3 concentrations of variable tested Only very low concentrations of variable were tested Liquid pulse was only technique utilized Contaminated all infusions (excluded from experiment) Use a variety of sunscreen brands More concentrations Have valid agar infusions Apply UV in conjunction with sunscreen More replicates

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