Researchers said Wednesday the tobacco industry of misled smokers over the safety of additives in cigarettes after they reanalyzed the data from a decade old study by scientists working for the American cigarette manufacturer Philip Morris.

The original study by the cigarette maker showed that there was “no evidence of substantial toxicity” associated with the additives studied.

However, researchers at the Centre for Tobacco Control Research at the University of California said, after conducting their own analysis that the original studies “cannot be taken at face value” and were designed to intentionally hide the dangers of the additives.

The researchers compared their assessment to the results from the original “Project Mix” tobacco sponsored study and found that 15 different poisonous chemicals increased by an average of 20 percent.

Furthermore, researchers said that for “unexplained reasons” Philip Morris had purposely de-emphasized 19 of the 51 chemicals tested in their results which included nine of the 15 chemicals that were significantly increased.

Stanton Glantz, the lead author for the new research, said that the results were unsurprising and said there was a long history of big tobacco manipulating scientific results to benefit themselves.

Glantz said tobacco firms had spent many years preparing for the increasing likelihood tougher regulation for their products, including the regulation of additives.

Researchers explained that additives were sometimes used to make smoke feel less irritating, to make cigarettes more addictive and to add better taste.

The study went over about 60 million pages of documents from the tobacco industry that had been turned over during litigation.

"While the procedures to collect the data themselves appear sound, the way that the data were analyzed and interpreted is not," researchers wrote.

In 2009, the Food and Drug Administration had prohibited flavor additives in cigarettes, with an exception on menthol.

Gantz said that the FDA and other law makers should now use the industry’s own data to eliminate the use of menthol and all other cigarette additives.