Publishing a study of tobacco-specific nitrosamines in American smokeless tobacco products (abstract here), Dorothy Hatsukami and colleagues at the University of Minnesota called for the FDA to issue “regulations…to reduce levels of…NNK and NNN in smokeless tobacco products to the lowest levels possible.” The authors make illogical and unscientific claims in their article and media interviews (here).
Claim 1: “The majority of smokeless tobacco users in the United States are not aware of …the tremendous variability in the levels of these chemicals across brands sold in this country.” Tremendous variability? Dr. Hatsukami reported that, with the exception of two products, the level of NNK+NNN varied from 0.64 microgram per gram of moist snuff to 3.89 micrograms (or, if you prefer, parts per million).
Claim 2: “The higher the level of exposure the greater the risk for cancer.” This statement is meaningless, as exposure to these agents has not been linked directly to human cancer. The studies cited in the article involve SMOKERS, who are exposed to thousands of other toxins. This is like claiming that golfers have a high risk for concussion, based on data from the National Football League.
The authors fail in their effort to make a cancer connection with a rat study from 1986, conducted by Dr. Hatukami’s colleague and coauthor, Dr. Stephen Hecht (here). He exposed the mouths of 10-week-old rats to enormous doses of NNN and NNK daily for over 131 weeks. The experiment was so aggressive that 86% of the rats died by trial’s end. Not surprisingly, Dr. Hecht produced more tumors in the rats getting high doses. Another result was entirely unexpected: In rats given the same massive NNN and NNK doses in snuff extracts, tumor production virtually disappeared.
It appears that smokeless tobacco contains beneficial agents that virtually cancel out the negative effects of even massive doses of NNN and NNK. That is probably happening with dippers and chewers, even though they are only exposed to minuscule levels of nitrosamines.
I recognized this important smokeless attribute a decade ago, when I published a research study showing that commercial tobacco products have moderate-to-high antioxidant properties, much like fruits and vegetables (discussed here).
There is one bright spot in the Minnesota study. The authors acknowledge “The lack of association between snus use in Scandinavian countries to [sic] oral cancer.” If only they and the broader scientific community would acknowledge that this profile also applies to modern American smokeless tobacco products.