Is that foundation you bought last fall still safe to wear? What about the lipstick you found in an old purse? We consulted some experts to find when cosmetics and other personal care products - often little more talcum powder, minerals and coloring - really should make their way from the bathroom counter to the wastebasket.

Here's a roundup of their best advice.

Mascara

How long to keep it: Three to six months

Expert explanation: Your eyes are a haven for bacteria, because they're wet and warm, explains Justin Klabin, who designs and manufactures personal care products. "When you apply the mascara to your eyes and put it back in the container, you're contaminating it a little every day," he said.

Eye cream

How long to keep it: Six months to a year

Expert explanation: Anything that goes near your eye needs to be watched carefully, said Jan Marini, president of Jan Marini Skin Research, based in San Jose, Calif. If the cream gets runny or changes consistency or smell in other ways before six months, throw it away.

Liquid foundation

How long to keep it: One year

Expert explanation: If the foundation starts to smell fatty or the color or fragrance otherwise changes, toss it, said Damiana Zullo, director of product and packaging development for Bliss.

Moisturizer

How long to keep it: One year

Expert explanation: Look for changes in color, consistency or smell.

Powder

(foundation, eye shadow, blush, etc.)

How long to keep it: Up to three years

Expert explanation: "Powders have a long, long life," Marini said. "Most powders don't have water, so there are few microbials that will grow."

Eye and lip liner

How long to keep it: Indefinitely

Expert explanation: As long as you sharpen before use, you're getting rid of impurities, Marini said.

Lipstick

How long to keep it: Two years or longer

Expert explanation: "It's so apparent as soon as you take the top off and put it under your nose," Zullo said. "If there's a strong, waxy smell, get rid of it."