Vaping while on oxygen therapy is not recommended. E-cigarette-related fires and explosions are a new risk to people and pets. In 2016, the FDA Center for Tobacco Products reviewed and summarized reports from other US government agencies, the news media, and scientific articles about e-cigarette-related fires and explosions, finding that some events have resulted in life-threatening injury, and permanent disfigurement or disability. Although there were no reports of pets being injured, the risk still exists. Pets that chew on the devices may potentially puncture the cartridges or batteries, or they may inadvertently turn on the devices. The US Food and Drug Administration recommends to keep e-cigarettes and all other tobacco products out of reach of children and pets at all times. Users may alter many of the devices, such as using them to administer other drugs like cannabis. E-liquid mixing is another way users tamper with e-cigarettes. Mixing liquid in an unclean area runs the risk of contamination. Users may add various flavorings and diluents. Vodka or other forms of alcohol may also be added. The addition of alcohol or nicotine could expose the user to more toxicants, especially when added in combinations. Some ingredients in e-liquids could be flammable; this risk is more of concern for users who are inexperienced or do not use protective gear. Users can adjust the voltage of some e-cigarettes. The amount of vapor produced is controlled by the power of the battery, which has led some users to adjust their e-cigarettes to increase battery power to obtain a stronger nicotine "hit", but there is a small risk of battery explosion. Some users add more or larger batteries to nonadjustable e-cigarettes, which may lead to battery leakage or explosion. The FDA stated to only use batteries recommended for use with the device. The FDA recommended to replace the batteries if they get damaged or wet. The extent to which teens are altering e-cigarettes, such as dripping the liquids onto the atomizer to get more nicotine intake, is not known. Marketing and advertisement play a significant role in the public's perception of e-cigarettes. Some tobacco users think vaping is safer than tobacco or other smoking cessation aids. It is generally considered by users that e-cigarettes are safer than tobacco. Emerging research indicates that vaping is not as safe as previously thought. Many users think that e-cigarettes are healthier than traditional cigarettes for personal use or for other people. Many youth believe vaping is a safe substitute to traditional cigarettes. A 2016 review suggests "that the perceived health risks, specific product characteristics (such as taste, price and inconspicuous use), and higher levels of acceptance among peers and others potentially make e-cigarettes initially more attractive to adolescents than tobacco cigarettes.