Agency (FEMA) adds that in the event of a building collapse, it is advised that you: Seek protection under a structure like a table Cover your mouth with your shirt to filter out dust Don't move until you are confident that something won't topple on you Use your phone light to signal for help, or call Important survival items Survivalists often carry a "survival kit." The contents of these kits vary considerably, but generally consist of items that are necessary or useful in potential survival situations, depending on the anticipated needs and location. For wilderness survival, these kits often contain items like a knife, water vessel, fire-starting equipment, first aid equipment, tools to obtain food (such as snare wire, fish hooks, or firearms), a light source, navigational aids, and signaling or communications devices. Multi-purpose tools are often chosen because they serve multiple purposes, allowing the user to reduce weight and save space. Preconstructed survival kits may be purchased from various retailers, or individual components may be bought and assembled into a kit. Controversial survival skills Some survival books promote the "Universal Edibility Test." Allegedly, it is possible to distinguish edible foods from toxic ones by exposing your skin and mouth to progressively greater amounts of the food in question, with waiting periods and checks for symptoms between these exposures. However, many experts reject this method, stating that even a small amount of some "potential foods" can cause physical discomfort, illness, or even death. Many mainstream survival experts have recommended the act of drinking urine in times of dehydration and malnutrition. However, the U.S. Army Survival Field Manual (FM 21-76) instructs that this technique is a myth and should never be used. There are several reasons to avoid drinking urine, including the high salt content of urine, potential contaminants, and the risk of bacterial exposure, despite urine often being touted as "sterile." Many classic western movies, classic survival books, and even some school textbooks suggest that using your mouth to suck the venom out of a venomous snake bite is an appropriate treatment. However, venom that has entered the bloodstream cannot be sucked out, and it may be dangerous for a rescuer to attempt to do so. Similarly, some survivalists promote the belief that when bitten by a venomous snake, drinking your urine provides natural anti-venom. Effective snakebite treatment involves pressure bandages and prompt medical treatment, and may require antivenom. See