[ 123 ] Earth and Space Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Refer to the following passage to answer the next nine questions. Approximately one billion people worldwide have vitamin D deficiency. This deficiency is thought to be largely due to insufficient exposure to the sun. In some cases, poor diet can also play a role. There is increasing evidence that vitamin D deficiency also increases a person’s susceptibility to autoimmune conditions. Additionally, a lack of vitamin D can impact bone development. The main source of vitamin D in the body comes from exposing the skin to sunlight. Just 10 minutes of exposure to ultraviolet B radiation wavelengths between 280 and 315 nm, five days a week, will give most people enough vitamin D. However, extended exposure to ultraviolet radiation from the sun is known to increase the risk of skin cancer. Widespread campaigns for the use of sunscreen and sun avoidance have reduced the incidences of skin cancers. However, sunscreens with sun protection factors of 15 or higher also decrease the body’s ability to synthesize vitamin D by 99%. Radiation Type UVA UVB UVC Linked to Aging Burning Wavelength 400 nm to 315 nm 315 nm to 280 nm 280 nm to 100 nm % reaching Earth at noon 0.95 0.05 0%—absorbed by ozone, molecular oxygen, and water vapor in the upper atmosphere % reaching Earth before 10 A.M. & after 2 P.M. 0.99 0.01 0 % reaching Earth (average) 0.97 0.03 0 According to the information in the passage, what are the two consequences of vitamin D deficiency?