It started with the sunscreen.

Scrutinizing a jumble of half-used bottles and tubes in search of sun-protection, I noticed 3 of every 4 had passed their expiration dates. One bottle of Coppertone (SGP) went back as far as April 2004.

I know enough to appreciate that a 5-year-old product is a sure toss, but what about the untouched $9.85 tube of Neutrogena Sun Block (JNJ) with the September 2008 expiration? Or the nearly full Banana Boat (ENR) that expired in March of this year?

I got the skinny from Anne Russell, my source/authority on all things health- and body-related. She’s a longtime fitness buff and editor-in-chief of VIV Magazine.

“Yes, sunscreen actually does break down,” she said. “Sometimes as quickly as after an hour or 2 on your skin, but that's a different scary story. Bottom line: It gradually loses efficacy, so if you want to keep using it, assume that 30 has dropped to 15 if it's over 6 months old and so on.”

This got me thinking about other products. Insect repellent, for instance. Checking the cupboard in my downstairs bathroom yielded 3 vintage cans and bottles. One appeared to be full.

“Now THAT stuff never goes bad, I think, hence the Hazmat disposal status,” Anne said. “If you're worried, replace, but you'd probably be safe (relatively speaking) with one bottle of DEET for the rest of life. Use it very sparingly and that life will probably be longer.”

Keep in mind, I don’t part with things easily. I once moved houses and packed a $1.29 box of Ronzoni lasagna, finally throwing it away 5 years later. But one thing my week’s mission made me see is that failing to check the supplies before heading to the store is a sure-fire way to waste money.

In that downstairs bathroom alone, I’d uncovered 37 expired health and beauty-related products with a value of at least $200. The prize was a bottle of Ipecac that expired in January of the year 2000. Hey, I know I am not alone! Some people are worse. Witness this!

So what’s the difference between expiration and sell-by dates? Which ones really matter?

This terrific Howcast video makes sense of a lot of it.

Turns out, I could have eaten the lasagna, but it may not have tasted so great. Packaged, canned and frozen foods seem to last forever. It’s just the quality that degrades.