Carcinogen Found in Mint and Menthol E-Cigs
Flavoring was banned from foods last year for cancer risk
In their risk analysis, Jordt and Jabba examined data from recent studies conducted by investigators with the CDC, evaluating the chemical composition of sample e-cigarette and smokeless tobacco products.
They calculated the margin of exposure (MOE) based on oral pulegone concentrations identified in the studies for five e-cigarette products (V2 Menthol, V2 Peppermint, Premium Menthol, South Beach Smoke Menthol, South Beach Smoke Peppermint) and one smokeless tobacco product (Skoal Xtra Mint snuff).
MOE is used by the FDA to calculate cancer risk associated with food additives. The FDA considers a food additive safe for ingestion if its concentration is 10,000 times lower than the concentration shown to be carcinogenic in rats, Jordt explained.
The researchers defined a light user as someone who used 5 mL of e-liquid, smoked a half pack of cigarettes or uses 10 grams of smokeless tobacco daily. Daily moderate use was defined as use of 10 mL of e-liquid, one pack of cigarettes, or 20 g of smokeless tobacco; heavy use was defined as 20 mL of e-liquid, two packs of cigarettes, or 30 g of smokeless tobacco daily.
MOEs for all products analyzed were found to be below the accepted MOE threshold of 10,000 for carcinogens, reflecting risk greater than considered acceptable.
“For the e-liquid with the highest pulegone concentrations, MOEs were between 1,298 and 3,084 for 5 mL daily consumption and 325 and 771 for 20-mL daily consumption, below the safety threshold of 10,000,” the researchers wrote. “Depending on consumption rates, MOEs for the e-liquids ranged between 325 and 6,012; for a pulegone-containing smokeless tobacco they ranged between 549 and 1,646.”
When exposures from the tested e-cigarettes were compared with those typically found in conventional menthol cigarettes (estimated to range between o.037-0.290 µg/g of pulegone), exposures were higher in all e-cigarette user groups, by factors ranging from 44 to 1,608.
There are no studies specifically examining the safety of inhaled pulegone, and Jordt acknowledged that carcinogenic risk may be different from that estimated for oral ingestion.
But he added that extrapolation of inhalation exposure levels from oral toxicity studies is common practice among regulators.
He added that the threshold for chemical inhalation exposures are typically lower than for oral exposures since “the digestive system is better equipped to handle chemical exposures than the lungs.”
“But we absolutely need studies to examine the long-term impact of pulegone inhalation exposure,” he said.
Other study limitations cited by the researchers included the limited data involving only 5 e-liquids and 1 smokeless tobacco product.
They concluded, however, that their findings “appear to establish health risks associated with pulegone intake and concerns that the FDA should address before suggesting mint- and menthol-flavored e-cigarettes and smokeless tobacco products as alternatives for people who use combustible tobacco products.”