The main dangers of using a Rival roaster, which is a type of Dutch oven, are from burns and electric shock. Burns can be sustained from steam, food cooking inside and the oven itself.
Dutch ovens are used for long, slow cooking and are traditionally lidded pots made from cast iron. Electric Dutch ovens have a metal pot which holds the cooking food inside a base that contains an internal heating element. Because the food inside is usually cooked in liquid, steam can escape from the pot when the lid is opened and burn the face and hands of the cook. To prevent this, the cook should open the lid away from himself and let the steam out slowly. Because the pot and its contents can become very hot, only the knobs and handles should be touched when it is on, with oven mitts used to remove the inner pot or cooked food.
Lethal electric shocks are also a danger. The pot should not be operated if it has a damaged cord, unplugged while still turned on, or immersed in water.