Background to my paper.  If you have any questions please e-mail me at:

Sun protecting agents are being used more often than ever before because of the high risks of skin cancer. UV radiation has more effect than creating skin cancer though. It has been linked to premature aging, immune suppression, cataracts, and sunburn (Manchester College, 2000). The United States Food and Drug Administration (FDA) has begun to monitor what type of ingredients that should be in sunscreens. There began a debate over which ingredients work better than others. 16 ingredients were introduced as something that should be used in the labeling of the product. Along with using these ingredients, the FDA also wants the manufacturers of these sunscreens to use the names in the labeling and formulation. Testing for both ultraviolet B (UVB) and ultraviolet A (UVA) protection have also been added to the list of things to do. The effective date was delayed to December 31, 2002, because of the debating over which ingredients are better (Dotzel, 2000).

Sunburning, melanoma, basal, and squamous cell carcinoma are caused by UVB light radiation. The belief was that if you could prevent getting sunburned, then you could prevent skin cancer (Thompson, 2000). Many scientists believed that UVB light radiation was the strongest, but later studies told something different, that UVA radiation is more harmful. UVA has been responsible for creating skin damage. For instance, photoaging and the development of skin cancers have been linked to the ultraviolet ray A. Sunscreens do a good job of blocking out the UVB rays, but do a poor job stopping the UVA rays (Thompson, 2000). With UVA being linked to cancer, studies have started to see how effective the sunscreen blocks out the rays. "Both laboratory and epidemiological studies indicate that sunscreens may not block the initiation or promotion of melanoma formation," stated Ronald D. Ley, Ph.D., at the University of New Mexico School of Medicine’s Steve Schifff Center for Skin Cancer in Albuquerque, N. M. (Thompson, 2000). Those studies have shown that sunscreen was not effective in blocking the harmful rays. Another problem with UV radiation is the pain that occurs while in the sun for a long period of time for people with sun allergies.

Sun allergies are rare. The ones that are most known are porphyrias. There are six types, they include acute intermittent porphyria, hereditary copropophyria, variegate porphyria, erythropoietic protoporphyria, porphyria cutanea tarda, and congenital erythropoietic protoporphyria. These porphyrias are inherited. It is active because of the reduced ferrochelatase that this allergy occurs (Emedicine.com, 2000). When people with any of these porphyrias are exposed to UV radiation of any type, the side effects differ greatly. The use of sunscreens have allowed the people with a porphyria to stay out in the sun longer than ever before. Yet the question of how well sunscreen works arises.

Sunscreens are mainly classified as PABA-free, UVA and UVB protected. The main active ingredients include ethylhexyl p-methoxycinnamate, oxybenzone, ethylhexyl salicylate, and homosalate. Many people choose sunscreens based on the Sun Protection Factor (SPF). It is widely accepted that the higher the SPF value, the better sun protection. In some cases that is true. In a SPF of 15 and a SPF of 45 the difference is that the 15 protects you from 93 percent of the sun’s rays, and 45 protects you from 98 percent. A SPF of 2 blocks half of the sun’s rays, while having no protection on gives you no protection whatsoever (Healthweek, 2000).

Many Americans spend numerous hours out in the sun daily. Some may be basking in the sun to get that golden brown tan, just having fun, while others are working. The question of what you can do to protect yourself from the suns harmful rays arises for many. What can you do to prevent damage to your skin? The answer may be sunscreen. But how effective is the sunscreen that you are putting on? The answers may be held with in the Japanese Medaka embryos.

The Oryzias latipes (Japanese Medaka fish) embryos are freshwater semitropical killifish. The embryo will hatch in 10 to 20 days, depending on the temperature. They are located in the areas of Japan, Taiwan, and southeastern Asia. They are most likely to be seen in rice paddies (Carolina Biological, 2000). They feed on mosquito larvae and have been used to control mosquitos in tropical climates (Sugiyama, et al., 1996). These embryos are a great specimen for the use of UV radiation testing. When the Medaka is exposed to UV radiation they will most likely die. They also have been used in studies about cancer and the interrelationship of GSH depletion, apoptosis, mutation, and cell proliferation following carcinogen exposure. This research shows that the medaka is an appropriate model for research (Kwak H, Lee M, Cho M).

This research shows that the sunscreen was effective in blocking out the UV rays. The SPF’s did not play a huge part in keeping the Japanese Medaka Fish Embryos alive; it was mainly the use of a sunscreen. There were some signs of poor development though. In the petri dish covered with SPF 4, there was an abnormal circulation and growth problem. In the control with UV radiation there was death of two embryos.

Based on the research, the conclusion is that the sunscreen was effective. However, the use of different SPF’s didn’t make that much of a difference. The control group that was exposed to UV radiation did show differences, including the death of two embryos. The conclusion of this research is that the sunscreens were effective in keeping the embryos alive.

More than one million Americans will develop one of the three forms of skin cancer, and over ninety percent of these cancers will appear on sun exposed skin. Moreover, every hour an American dies from skin cancer (Networks, Inc. 2000). This is why more people are being conscientious about their hours in the sun and the protection they use. The purpose of this research is to test sunscreen effectiveness. This will be done by observing Japanese Medaka fish embryos development.

I hypothesize that the larger the SPF number, the better it will protect the Japanese Medaka embryos. Also, having both UVA and UVB light protection will better ensure normal embryo development. Some signs of poor development would include:

1. Abnormal circulation

2. Varied heartbeats

3. Slow developmental rate

4. Abnormal features

5. Death of the embryo

1. Separate Embryos

2. Label 2 petri dishes Control without UV, CN1 and CN2

Label 2 petri dishes Control with Short wave (253 nm) UV, C and Co

Label 2 petri dishes SPF 4

Label 2 petri dishes SPF 8

Label 2 petri dishes SPF 15

Label 2 petri dishes SPF 30

Label 2 petri dishes SPF 45

3. Prepare rearing solution

4. Transfer 25 mL of the rearing solution into every dish

5. Place 4 embryos into each dish

6. Coat petri dish covers with a thing layer of appropriate SPF

7. Treat embryos with UV light for 20 minutes

8. Examine embryos twice a day for developmental changes

9. Repeat steps 6-8 for 7 days

10. Video tape embryos development and changes

Control without UV developed normally

Control with UV had two deaths

SPF 4 had blue dots, spotted bodies, and unusual circulation

SPF 8 developed normally

SPF 15 developed normally

SPF 30 developed normally

SPF 45 had yellow embryos that developed normally