Tobacco companies are legally prohibited from using words like “light” or “mild” to market cigarettes. But in a new study, researchers say the industry is still finding ways to communicate those same messages.

“Light” cigarettes came into fashion in the 1960s, shortly after the U.S. Surgeon General made the connection between smoking and disease. These kinds of cigarettes have ventilation holes that let more air in and limit the amount of smoke a person takes in.

But studies show that smokers compensate for that difference: smoking more cigarettes, inhaling deeper, blocking the ventilation holes with their fingers or taking more puffs per cigarette.

Terms like “lights” and similar descriptors were banned from tobacco packaging and marketing by the U.S. Food and Drug Administration in 2010, on the grounds that they conveyed a misleading message of reduced health risks. The FDA gained the authority to regulate tobacco products in 2009, thanks to the Family Smoking Prevention and Tobacco Control Act.

But now two researchers from the Harvard School of Public Health -- after examining retailer manuals and manufacturer reports from tobacco giant Phillip Morris, scrutinizing cigarette sales data and conducting a national opinion survey -- say manufacturers have just switched to different code words. Their study was published online Wednesday in the journal Tobacco Control.

Different categories of Marlboro, Parliament, and Virginia Slims sub-brands, once known as ‘Light’ or ‘Ultra-light,’ have been rebranded as ‘Gold’ and ‘Silver,’ respectively; Camel Lights became Blues.

"Some cigarette and smokeless packaging is changing, but the product remains the same," said one Phillip Morris flier distributed to retailers – and specifically meant not to be shown to customers -- according to the paper.

The researchers’ phone survey, which included more than 500 smokers, found that more than two-thirds of the smokers correctly associated the packaging color of their preferred brands with its former ‘light’ or ‘ultra-light’ or full-flavor label. More than 90 percent of smokers surveyed found it either “somewhat easy” or “very easy” to identify their usual brand, even without the ‘light’ or ‘ultra-light’ label.

Senior author Hillel Alpert said he and his colleague were not surprised by their findings.

“These manufacturers have a long history of deception and the changes that we observed were quite overt,” Alpert said in a phone interview.

Alpert and his colleague write in their paper that the FDA should have the authority to extend the packaging term ban to include the use of colors that contribute to “the deception of reduced risk.”

They also raise the question of whether or not the rebranded cigarettes constitute new products under FDA relations, which would have required premarket approval from the agency before the products went on sale.

A representative for Phillip Morris did not respond to a request for comment on Wednesday.