Blowing Smoke: Are Cigarette Additives Toxic?

Brenda Wisehart smokes a menthol cigarette in Miami, Fla., in this file photo. A recent report calls into question research data from Philip Morris that determined additives in cigarettes are not toxic. (Joe Raedle/Getty Images)

Everyone knows that smoking is bad for you; but consider that a cigarette is more than just tobacco leaves.

By conservative estimates, according to research commercial cigarettes contain about 600 chemicals and additives— ammonia, DDT, chloroform, benzene, arsenic, and lead, just to name a few.

While some components are undoubtedly toxic, the health risks associated with smoke inhalation from other additives (such as menthol, sugars, and various herbs) are not as clear. These ingredients contribute to the unique character of a particular cigarette, and allow manufacturers to modify the sensory and pharmacological properties of their products.

In 2009, the U.S. Food and Drug Administration took a closer look at these additives with an eye toward safety and possible regulation. But the jury, it seemed, was already in.

Anticipating the impending eventuality of additive regulation, the tobacco industry conducted several studies in the late 1990s. Philip Morris’s Project MIX examined three combinations of 333 cigarette additives for possible toxicity. In 2002, analysts published a report in Food and Chemical Toxicology concluding that there was no evidence of substantial toxicity attributable to the additives.

A study published last week in PLoS Medicine draws a different conclusion. Analyzing the same data collected in Project MIX, researchers from the Center for Tobacco Control Research and Education, and the University of California at San Francisco, found that these additives contribute a great deal to cigarette toxicity.

According to researcher Stanton Glantz, professor of Medicine at the University of California at San Francisco, Philip Morris worked politically to get the regulations they wanted.

“If you simply take their own data and interpret it properly, you have strong evidence that putting the additives in the cigarettes increases the toxicity of the smoke,” said Glantz in a video for SciVee.

In the PLoS study, Glantz and his colleagues examined previously secret industry documents that revealed changes in analytical protocols after initial findings indicated a clear additive-associated increase in cigarette toxicity. They found that industry analysts intentionally obscured laboratory data in their presentation to get the results they wanted.

“This is a very important conclusion from a regulatory perspective because if Phillip Morris could convince the FDA that putting these additives in cigarettes didn’t really affect their toxicity, than there would be no reason to regulate these additives, or demand that they be taken out,” observed Glantz.

In addition to suspicious presentation of data, researchers found other methodological red flags in the MIX Project. For example, MIX used screening tests designed to give yes or no answers as a method to describe dose response measurements. In their animal toxicology studies, MIX tests were done with such low sample sizes that, according to Glantz, no regulatory agency could use it to evaluate safety.

Researchers said that larger sample sizes would probably have detected a much broader range of adverse effects attributed to additives than identified in the journal publication, suggesting that the published papers “substantially underestimate the toxic potential combination of cigarette smoke and additives.”

So why didn’t the peer review process catch such glaring problems? Glantz says that Food and Chemical Toxicologies has very strong ties with big tobacco, and the industry knew this journal would protect their interests.

“It was an inside job,” explained Edward Carmines, lead scientist of Project MIX, in a 2001 email. “We went to a journal whose editor knew us. The comments were technical trivia.”

The PLoS report recommends that the FDA and similar agencies conduct their own independent analysis of Project MIX data, and Glantz advises regulators to ban cigarette additives until the tobacco companies come forward with “well-powered, well-designed studies demonstrating safety.” Given the data found in Project MIX, researchers say it’s highly unlikely.

“You really can’t take anything at face value from a cigarette company,” said Glantz.