Most shark attacks occur less than 100 feet from the shore. More people are killed by bee stings and lightning than by shark attacks. Worldwide about 30 people die each year from shark attacks, which means a person has a one in 300 million chance of being killed by a shark. A shark attack most often occurs when a shark mistakes a person for a seal or other animal.
The new 2010 recommended daily allowance (RDA) is 600 IU for those 1-70 years of age and pregnant or breastfeeding women, and 800 IU for those over 71 years of age. An adequate blood level of vitamin D is 20 nanograms per milliliter, which can be achieved through daily skin exposure to sunlight.
There is another blood test for normal vitamin D levels, called Vitamin D 1,25 Dihydroxy level or 1,25(OH)(2)D. The Vitamin D, 1,25 Dihydroxy level does not have a major change until normal Vitamin D levels, or 25(OH)D, drops to levels that are considered a VERY severe Vitamin D deficiency. 1,25 dihydroxy-vitamin D or 1.25 Dihydroxy level or 1,25(OH)(2)D has the normal values are usually listed as 20-76 pg/ml.