“Natural” Sunscreens Although More Expensive are Not More Effective at
Preventing UV Exposure
Abstract
Skin cancer, the most common type of cancer within humans, has
approximately 3.5 million cases each year. The evidence supports that
the use of sunscreen can help to prevent different forms of skin
cancers. There are a multitude of brands that make sunscreen, each
claiming to be better than the next. The two main types of sunscreen are
physical and chemical. Physical sunscreens deflect the ultraviolet (UV)
rays of the sun and are normally made of zinc oxide or titanium dioxide,
whereas chemical sunscreen absorb the suns UV rays and can be composed
of many different ingredients. It was hypothesized that the physical
sunscreens would do a better job at protecting against the sun’s rays
than the chemical sunscreen brands. In this experiment E. coli growth
was tested under UV light exposure with an application of five different
brands of sunscreen. The control was exposed to UV with no sunscreen
protection. After exposure to the UV light, the bacteria were set aside
to grow and colonies were counted for survival. A statistical ANOVA was
used to look at the significance between each brand of sunscreen,
physical and chemical. Through the statistical analysis it was found
that there was no significant difference between each brand of
sunscreen. However, there was a significant difference in E. coli counts
between each sunscreen application and the control. There was no
statistical difference in E. coli counts between sunscreen types,
indicating both types of sunscreen provide the same amount of protection
from UV radiation.