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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Looking at the sun may not only cause headache and distort your vision temporarily, but it can also cause permanent eye damage. Any exposure to sunlight adds to the cumulative effects of ultraviolet (UV) radiation on your eyes. UV exposure has been linked to eye disorders such as macular degeneration, solar retinitis, and corneal dystrophies.
Increased intake of vitamin D has been shown to reduce fractures up to 25% in older people.
The word drug comes from the Dutch word droog (meaning "dry"). For centuries, most drugs came from dried plants, hence the name.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.