The transportation of dangerous goods on aircraft is regulated by international and national regulations, such as the International Civil Aviation Organization's Technical Instructions for the Safe Transport of Dangerous Goods by Air. Dangerous goods include items such as flammable liquids, explosives, and radioactive materials. These goods must be properly classified, packaged, labeled, and declared to the airline before transport. Airlines may have additional restrictions or requirements for dangerous goods, and certain items may be prohibited altogether. Passengers are also prohibited from carrying hazardous items in their carry-on or checked baggage, and are subject to security screening to detect prohibited items.