When working in industries where metal slag is a threat, protection must come first. When working in industries where metal slag is a threat, protection has to come first. The dangers that casters and smelters face are among some of the most serious in any industry. Molten metals in any amount at any time pose a threat to life and limb. Casting metals such as copper, iron, zinc and aluminum exposes workers to large amounts of molten slag. Any spills or run offs from these types of operations can be deadly. A burn injury in this industry is very serious and the results can be devastating.