As doctors warn it can cause a dangerous reaction with a host of common drugs... 1  Researchers warn that grapefruit reacts with many medicines. 2  The fruit can cause devastating side-effects from stomach bleeding to kidney problems. 3  Doctors say the public is ignorant to the dangers and putting themselves needlessly at risk.
According to the definition of the question (based on light reflection and not light emission), a well-polished mirror is the the whitest substance on earth. The main reflection layer is usually made out of silver.
It has an entry in the Guinness Book of Records as having the whitest sand in the world (officially at Hyams Beach, though many others around there are similarly blessed) and the astonishing fact that the bay is at least six times bigger in volume and four times bigger in area than Sydney Harbour.