CHICAGO (WBBM) - Here's something to think about as you drink your morning coffee at work.

WBBM's Steve Miller reports.

Wait until your cup is empty - then turn it over.  Does it have a number 6 on it?  And below that, "PS"?

That PS is for polystyrene.  Styrofoam.  And if hot coffee or hot tea is your drink of choice, polystyrene maybe shouldn't be your cup of choice, says Paul McRandle, deputy editor of The Green Guide, published by National Geographic.

"There is a concern that styrene itself, one of the chemical components which is a possible human carcinogen, may leach into coffee or (any) hot liquid."

And McRandle says there's another reason to not use Styrofoam.

"Given that polystyrene is not all that readily recyclable, we've suggested - and many companies have already done this - switching to cardboard."

The companies that make Styrofoam cups say their product is safe and meets all FDA requirements - and they say some questions raised over the years have attained "urban legend" status.

The Green Guide also is talking about the office water cooler.

That's if your office water cooler has one of those five-gallon plastic bottles. Chances are there's a number-7 on the bottom of it and it's made of polycarbonate.

Perhaps not a good idea, says Paul McRandle, deputy editor of The Green Guide, published by National Geographic.

"We don't recommend using them."

Again, some of the recommendations of The Green Guide differ from the federal government's.

Tap water in most places is fine, McRandle says. And he says if you don't use a bottle made of polycarbonate, you'd avoid possible exposure to bisphenol-A, which some say may cause cancer.

Many plastic baby bottles are also made of polycarbonate, and The Green Guide doesn't recommend them either.

The Food and Drug Administration has declared them safe.

However, Congress is considering a ban on bisphenol-A in some products, and Canada says it wants to ban the use of bisphenol-A in baby bottles.

On the Net: www.thegreenguide.com