EARTHWATCH : What’s Your Bag? : * Choosing paper or plastic at the store can be difficult, but a reusable sack is the best option.

“Paper or plastic?” the boy asks. It was a mundane question at the beginning of the ‘80s. At first I was a bit annoyed at being asked. Couldn’t the store management figure out which was cheaper for them? Certainly I wasn’t going to benefit either way. With paper, your arms ache, and you can’t carry more than two bags at a time. Plastic cuts into your fingers, and all your groceries instantly migrate through any hole they can bore. Double bagging with paper and plastic only compounded the problems.

Then came the environment. More annoyance about “paper or plastic.” Which is more environmentally correct? It saves trees if you go with plastic but is it biodegradable? All that landfill. All those cormorants with fatal plastic bibs. So, we go back to paper, only to discover that many stores aren’t recycling it yet. And we know now that the 3-foot-tall stack of brown bundles by the bag boy’s knee could cost the life of a tree from the rain forest.

The answer, it turns out, is the one I wanted to give from the beginning when I found it so annoying to be asked. Paper or plastic? Neither. The answer is the string bag. Like in Europe. They cost a few dollars and last forever.

I’m talking about something that looks like a finely woven basketball net to hold your groceries and has comfortable webbing handles like a gym bag. They are usually made of white cotton string, but they also come in a variety of rainbow colors. In either case, they are washable. They fold up, of course, to less than the size of one glove. You can keep one in the car and one in your coat pocket, the bottom of you purse or even in a child’s backpack.

Speaking of children, they will like the multicolored species of string bag to carry or hang up basketballs, beach balls and other unwieldy things that you would otherwise be stuck carrying. The main environmental thing about this idea is that it’s something reusable. This means there are no trees being cut down, petrochemicals being brewed or energy resources being used up to process and transport the paper or plastic bags. Don’t forget that even bags made from recycled materials, whether paper or plastic, still have to be reprocessed and re-transported, chewing up our energy resources and adding to the price of the groceries.

Anything reusable is also a little blow against fancy packaging. You are joining the fight to make stores and manufacturers take stuff out of the layers of wrapping they are charging you for.

I know the string bag doesn’t make sense when you go in for a 12-bag-at-a-time weekly shopping trip. My string bag stays with me for those dozens of other times I’m asked how I want to carry my purchases home. When I have no choice, I choose paper because it is a renewable resource, and petroleum is not.

I also ask if the bags are recycled. If the answer is no, I say they should be if the store wants savvy customers to keep shopping there.

This may seem hard-nosed but I’ve noticed two things lately. Prices aren’t higher in stores that do right by the environment. And merchants are much more responsive to this kind of request than they used to be. The slow learners among them have lost customers to the quick learners, and word gets around.

The wicked little secret is, by doing a few things differently at home, you are, bit by bit, getting these ideas out to the neighborhood, the store, city hall and the world.