Salivary acetaldehyde increase due to alcohol‐containing mouthwash use: A risk factor for oral cancer

Increasing evidence suggests that acetaldehyde, the first and genotoxic metabolite of ethanol, mediates the carcinogenicity of alcoholic beverages. Ethanol is also contained in a number of ready‐to‐use mouthwashes typically between 5 and 27% vol. An increased risk of oral cancer has been discussed for users of such mouthwashes; however, epidemiological evidence had remained inconclusive. This study is the first to investigate acetaldehyde levels in saliva after use of alcohol‐containing mouthwashes. Ready‐to‐use mouthwashes and mouthrinses ( n = 13) were rinsed in the mouth by healthy, nonsmoking volunteers ( n = 4) as intended by the manufacturers (20 ml for 30 sec). Saliva was collected at 0.5, 2, 5 and 10 min after mouthwash use and analyzed using headspace gas chromatography. The acetaldehyde content in the saliva was 41 ± 15 μM, range 9–85 μM (0.5 min), 52 ± 14 μM, range 11–105 μM (2 min), 32 ± 7 μM, range 9–67 μM (5 min) and 15 ± 7 μM, range 0–37 μM (10 min). The contents were significantly above endogenous levels and corresponding to concentrations normally found after alcoholic beverage consumption. A twice‐daily use of alcohol‐containing mouthwashes leads to a systemic acetaldehyde exposure of 0.26 μg/kg bodyweight/day on average, which corresponds to a lifetime cancer risk of 3E−6. The margin of exposure was calculated to be 217,604, which would be seen as a low public health concern. However, the local acetaldehyde contents in the saliva are reaching concentrations associated with DNA adduct formation and sister chromatid exchange in vitro , so that concerns for local carcinogenic effects in the oral cavity remain. © 2009 UICC