Look for certifications, not marketing claims, to gauge a product's true environmental impact.

RODALE NEWS, EMMAUS, PA—Aiming to combat greenwashing—the practice of using ambiguous phrases and misleading terms to get you to believe a product is environmentally friendly when it really isn't—Wal-Mart has announced plans to launch a new "Sustainability Index" for all the products it sells. The company hopes to create a system in which its suppliers assess the environmental and social impacts of their products, and then translate those assessments in a way that's useful for shoppers. However, the general public might not see the debut of the system for up to five years.

In the meantime, wherever you shop, here are five reliable green labels that will ensure you're getting the ecobenefits you pay for:

# 1: USDA Organic
Where You'll See It: Food and personal-care products.

What It Means: USDA Organic certification is the only guarantee that the food you're buying was produced without pesticides, genetic modification, irradiation, or fertilizers containing sewage sludge, and it guarantees that livestock and poultry weren't treated with antibiotics or growth hormones. It's illegal for any food producer to use the term "organic" on a food label if the product doesn't meet the USDA criteria. Products containing 95 to 100 percent organic ingredients can bear the USDA seal, while products with at least 70 percent organic ingredients can be labeled "made with organic ingredients."

The meaning of the label can be less clear when used on personal-care products. Certified organic products must be made with at least 95 percent organic ingredients in order to bear the USDA seal, but the U.S Food and Drug Administration, which regulates cosmetics and personal-care products, hasn't put any restrictions on the use of the term "organic" on labels, in marketing materials, or as part of a product's name. So any personal-care-product manufacturer can label a product as organic, regardless of what's actually inside. Some cleaning products have also started advertising themselves as organic, but the USDA has yet to establish standards for household products, so there, too, the label isn't very reliable.