Planning a midwinter vacation to a tropical clime? Don't forget the sunscreen.

If you bought new sunscreen last summer, it should still be effective (it lasts about a year). When in doubt, however, buy new.

When you do buy, buy smart. Read the label and avoid sunscreens that contain oxybenzone (also known as benzophenone-3).

A study from the Centers for Disease Control and Prevention shows that nearly all Americans are contaminated with this popular sunscreen chemical. It was deemed safe in the 1970s, but new evidence has cast doubt on that. It has been linked to allergies, hormone disruption and cell damage, according to the Environmental Working Group. It's linked to low birth weight in baby girls whose mothers have been exposed during pregnancy.

The EWG recommends using sunscreens without oxybenzone (benzophenone-3). Choose those with zinc or titanium oxide as the active ingredients. Finding them is not easy. To speed your search, look for Blue Lizard (anything without oxybenzone), California Baby, Kiss My Face (paraben-free series), Neutrogena Sensitive Skin Sunblock, Olay Defense Daily UV Moisturizer (with zinc), Walgreens Zinc Oxide for Face, Nose and Ears, CVS with Zinc oxide.

When using sunscreen, the EWG also recommends SPF 30 or higher and at least 7 percent zinc oxide or titanium dioxide for broad-spectrum protection. Avoid sprays or powders, so there's no chance of inhaling chemicals, as well as sunscreen with bug repellent.