BIRD-FRIENDLY, shade- grown and cage-free are just a few of the new marketing labels being plastered on food packages, and if you do not have a clue about what they mean, you are not alone. Even when you do, what proof is there that the claims are accurate?

Now that organic labels have become commonplace, a new kind of feel-good labeling is making its way to the grocery store. In its broadest terms, this "green shopping" movement deals with man's relationship to the environment, and the treatment of farmworkers, just two topics that led to riots last year at the World Trade Organization conference in Seattle.

Doing well by doing good is not a new idea, of course. Ben & Jerry's and Newman's Own are the most obvious success stories. Ben & Jerry's mentions its use of recycled paper for its ice cream cartons, and Newman's has famously donated its profits and uses organic ingredients in its salsas and other products. Stonyfield Farm has taken things a step further. Its yogurt containers boast: "We give 10 percent of our profits to the planet."

But a more narrow comparison can be drawn to the early days of organic food, when anyone could claim a food was grown organically without any evidence, and to the days before nutrition labeling was regulated, when a product like vinegar could be labeled cholesterol-free.

Once again, the watchword wherever food is sold is: buyer beware.

Federal law requires all labeling and advertising to be "truthful and not misleading," but regulatory agencies admit they do not have the resources to monitor compliance unless someone discovers life-threatening claims.

As a result, a new certification industry has sprung up, following the example of the organics industry, which has established independent certification. Organizations like the Rain Forest Alliance charge for their seal of approval. It took almost 10 years for the alliance to certify that Chiquita Brands International, one of the largest marketers of bananas in the world, had met its criteria for the Eco-OK Better Banana label. The program requires conservation, pollution control, worker safety and less use of pesticides.

Pacific Rivers Council's Salmon- Safe has certified some 40 farms, dairies and vineyards in the Pacific Northwest for improving farming practices to restore water purity to salmon habitats. Some wine labels already carry the Salmon-Safe logo. The Smithsonian Migratory Bird Center is certifying coffee that is shade-grown, a method that does not require clear cutting of forests and is bird-friendly, as it does not destroy the habitat of migratory birds.

Consumers Union has just opened a Web site, www.eco-labels.org, that is useful in sorting out the standards and claims of various certifying agencies. Otherwise shoppers have to call or send e-mail to a company to ask what a claim means and what proof there is for it.

Gerald Celente, editor of the newsletter Trends, said that "eco-friendly is going to be a huge business, particularly when outbreaks of foot-and- mouth disease and mad cow disease hit us." And he is convinced they will.

Sunspire, which makes certifiably organic chocolate chips, claims on its labels that it supports rain forest ecosystems. Asked what that means and how it can be verified, Maggie Puertas, the company's sales office coordinator, said, "That's a good question." She added that only the president of the company could answer it, and he did not return two phone calls.

Sea Bear, a smoked-salmon processor, claims its fish is wild and caught by hook and line, which suggests that it is of better quality than salmon that is farmed and netted, and environmentally more desirable. A company representative said it does its own verification of how the salmon is caught and where it comes from.

Egg cartons offer some of the most interesting reading, although the words are seldom enlightening. One company says there is no animal fat in the feed. Does that mean there are other animal parts in the feed? Other egg cartons claim that the hens are "cage-free." Is that meant to suggest that the chickens are free- range or simply that they are not in cages but in large enclosed areas where they stand beak to beak?

One of my favorite labels is from a chicken producer that says its birds have "no artificial hormones." A double asterisk beside the statement leads to this notice: "U.S.D.A. regulations prohibit the use of artificial growth stimulates and hormones in this product." The company is making a virtue out of not doing what it is not permitted to do.

Tensie Whelan, executive director of the Rain Forest Alliance, calls that kind of labeling the ecological version of whitewashing. "Green-washing schemes make a company that does not have a good environmental record look better," she said.

Katherine DiMatteo, executive director of the Organic Trade Association, who has spent many years making order out of chaos in the organic world, sees such claims as a threat. "If consumers lose faith in product labeling, we'll be affected by that," she said.