In an effort to cut calories, dieters read food labels; now, leading players in the global beauty market want to add carbon emission data to their labels to help shoppers make environmentally-friendly choices when it comes to shampoos, conditioners and other personal care formulas. 

Unilever may introduce carbon-footprint details for all 70,000 of its products, and is exploring how best to gather and present the information. The company says sales of brands perceived as sustainable have grown faster than those of brands that aren’t. Not to be outdone, L'Oréal announced that carbon labels will be available for all its rinse-off products by next year. The world's largest beauty company already provides an online environmental impact score, including carbon emissions, for its Garnier hair products in France.

But experts say consumers may not be ready to digest that kind of information just yet. Moreover, companies could use the labels to greenwash consumers, warned Dexter Galvin, director at the Carbon Disclosure Project.

“It could be hugely positive, or hugely negative since companies could bamboozle people with numbers,” he told The Wall Street Journal.

To help level the playing field, Colgate and Unilever are working with the World Business Council for Sustainable Development to improve the availability of verified, firsthand product-level emissions data. Last month, they introduced a program to coordinate the exchange of carbon data between companies.

Consumers continue to call for transparency, but the question remains, just well do they understand the data?