Bleach or Burn

If ocean acidification doesn't get them, corals might be doomed to death by . . . sunscreen. A recent study found that chemical compounds in cream-based sunscreens contribute to bleaching in coral reefs by making algae (the symbiotic partner of coral) susceptible to viral infection. This is bad news for corals and conscientious swimmers. The CDC reports that skin cancer is the most common form of cancer in the United States, so it's not wise to snorkel without some protection. Sunscreen remains a recommended form of sun protection; people are also advised to seek shade whenever possible, wear protective clothing, and avoid midday sun.

-- D.W.

Sources: CDC , Washington Post , San Francisco Chronicle