Washington, June 20 : A new study from Harvard School of Public Health (HSPH) researchers has revealed that tobacco manufacturers have continually changed the design and ingredients of their cigarettes over time, and that such changes have exceeded acceptable product variance guidelines.

The researchers say that consumers who buy the same brand of product are not made aware of the alterations, and how they might affect their levels of addiction or harm.

The findings at a time when U. S. President Barack Obama is preparing to sign a bill giving the Food and Drug Administration (FDA) oversight of the tobacco industry.

"I hope the FDA requires disclosure of any changes made to tobacco products and that the changes are disallowed if shown to increase appeal, addiction and harm," said Greg Connolly, director of the Tobacco Control Research Program at HSPH.

During the study, the researchers examined internal tobacco company documents released following the 1998 Master Settlement Agreement.

Connolly and lead author Geoffrey Ferris Wayne say that the documents describe significant changes made to commercial products over time, including blend, processing, casing, flavouring and physical design features.

The researchers observed that despite the constant innovation of tobacco products, which in many cases had exceeded the levels of acceptable variance established within the tobacco industry, the changes were not disclosed to consumers.

"Even incremental changes that occur over a period of years can result in significant design differences. The resulting product may have altered chemistry or delivery, yet the smoker is largely unaware of these changes. This underscores the need for industry transparency and accountability," said Ferris Wayne.

Connolly and Ferris Wayne suggest that all changes to tobacco products be reported to the FDA until regulators have a system in place for assessing product revisions.

According to them, no changes should be allowed until they have been scientifically shown to reduce addiction or harm.

The study appears in the "Online First" section of the Journal of Tobacco Control. (ANI)