Q I'm going to Mexico this month and I was wondering: Can I use sunscreen from last summer? What about safety? I heard that some sunscreens have ingredients that are harmful. How do I know?

A Sunscreens typically last a year. So if you bought new sunscreen last summer, it should still be effective. When in doubt, however, buy new. Tropical sun is strong.

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 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 (EWG). It's linked to low birth weight in baby girls whose mothers have been exposed during pregnancy. And it's a "penetration enhancer." It helps other chemicals penetrate the skin.

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. You'll be reading lots of labels in the sunscreen aisle, and finding that most sunscreens contain oxybenzone. But oxybenzone-free suncreens are out there.

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

• At least 7 percent zinc oxide or titanium dioxide for broad-spectrum protection

• Avoiding sprays or powders so there's no chance of inhaling chemicals

• Avoiding sunscreen with bug repellent (you may end up with too much pesticide exposure because you need to reapply sunscreen more often than you do bug repellent).

Send your questions to Fixit in care of the Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488, or call 612-673-7032, or e-mail fixit@startribune.com. Past columns are available at www.startribune.com/fixit. Sorry, Fixit cannot supply individual replies.