Daily use of Listerine mouthwash may increase the risk of two serious cancers, warns a new study. Researchers found that the alcohol-based mouthwash contributed to different levels of oral bacterial populations linked to an increased risk of esophageal and colorectal cancer. For the study, conducted at the Institute of Tropical Medicine in Antwerp, Belgium, the researchers investigated the impact of daily mouthwash use on STI risk among gay men. They specifically set out to find ways of reducing the incidence of gonorrhea, chlamydia, or syphilis in men who have sex with men. The 59 participant…