1: A tanning salon located near campus gives a 20% discount to students. Two women on your dorm floor have been using the tanning beds. When you question the safety of this practice, your friends claim that being exposed to 20 minutes of UV light from tanning beds is actually safer than being in the sun for a few hours. When you point out that tanning beds can cause skin cancer, they say that most salons have switched to bulbs that have only one kind of UV light, making them much safer than before. They also claim that using tanning beds makes them look and feel more healthful, in part because using tanning beds helps them to get the recommended amount of vitamin D.
The use of tanning beds is not only safe, it improves health.

Questions

1. Even if there were evidence that tanning for 20 minutes was safer than being in the sun for a few hours, would this provide evidence that tanning beds are safe? Why or why not?
2. UV light from the sun occurs in two different wavelengths, longer UVA rays and shorter UVB rays. UVB rays cause the surface of the skin to burn while the longer UVA rays penetrate farther into the skin, making it more likely that the rays will damage DNA. Early versions of tanning beds used UVB bulbs, but most have now switched to UVA bulbs.
From an economic standpoint, why might it benefit tanning bed manufacturers and salon owners to switch to UVA?
3. A tan occurs when damaged skin temporarily produces more melanin to prevent further damage. A tan is evidence that the skin has been injured. Should a tan skinned be considered evidence of good health?
Why or why not?
4. Although sunlight is required for the body to synthesize vitamin D, the American Cancer Society recommends that no one be exposed to more than 15 minutes of sunlight before applying sunscreen. If you wanted to ensure that you were getting enough vitamin D without exposing yourself to UV light from any source, what could you do?
5. Consider your answers to questions 1–4 and explain why the original statement bolded above sounds right, but isn’t.