It’s surprising what passes for “science” in some journals today. Chemical Research in Toxicology has published a study from the University of California’s Berkeley and San Francisco campuses making this extraordinary claim: “Children living with smokeless tobacco [ST] users may be exposed to carcinogenic tobacco-specific nitrosamines [TSNAs] via contact with contaminated dust and household surfaces.”
The research was an offshoot from a larger effort looking for an environmental cause of childhood leukemia. Families who participated in the study were divided into three groups: non-users of tobacco, smokers and ST users. The contents of dust bags from their household vacuum cleaners were analyzed for NNN and NNK, two TSNAs that are considered to be causes of cancer.
Almost every household – even those with no tobacco users – had NNN and NNK in their dust, but researchers found “higher” levels of these agents in every gram of dust from an ST home – about 5 to 10 nanograms. Keep in mind that a nanogram is one billionth of a gram, and a gram is less than four one-hundredths of an ounce.
Each gram of moist snuff contains about 5-10 micrograms of NNN/NNK, about 1,000 times higher than the dust in this study (see my previous blog entry. At one can a day (32 grams), the typical ST user is exposed to 32,000 times more NNN and NNK than the hypothetical child who eats a gram of dust every day. It is well established that long-term use of ST even at that level is not associated with a significant increase in risk for ANY cancer.
The California exposure data may be accurate, but the findings are of no practical consequence, other than to serve as fodder for hyperbolic anti-tobacco claims.