My preliminary research was done on the affects that ultraviolet radiation has on the human body. I looked at DNA repair mechanisms and immune system suppression. In my experiment, I choose to focus on how ultraviolet radiation affects the normal flora (or bacteria) that are found on the body. Since the normal flora tend to help the body, I reasoned that it would be interesting to find out how harmful ultraviolet radiation is to them.

I cultured bacteria off my arm and grew them in petri dishes, in nutrient agar, at 37° C. Once a day, I exposed the bacteria to ultraviolet radiation. The four groups were a control (that wasn’t exposed), a five minute exposure group, a ten minute exposure group, and a fifteen minute exposure group. All exposure lengths were cumulative. The experiment was conducted for about a week.

During the experiment, I measured the percentage of the surface area of the petri dish that was covered, the number of different types of bacteria, and the diameter of the largest colony. The data indicated that the control bacteria were the most abundant and diverse. It also indicated that the longer the ultraviolet radiation exposure was, the more harmful it was. This considered, I suspect that ultraviolet radiation may be harmful to the normal flora that live on the body, as well as harmful to the skin cells.