Hazardous waste

Waste includes more than trash. Spent solvents, leftover paints, used batteries, corrosive cleaning solutions and expired lab chemicals can all become waste once they are no longer intended for use. A product that is harmless on the shelf can still need to be managed as hazardous when thrown out.

The test has two routes. A waste may be listed, meaning the regulations name particular wastes or waste streams. Otherwise it is tested against four characteristics. Ignitable wastes burn readily, corrosive wastes are strongly acidic or basic, reactive wastes are unstable or react with water, and toxic wastes can release harmful substances that leach into groundwater.

Generators are responsible for the decision. They label containers, store waste in a controlled area, limit how long it stays, and ship it with a manifest to a permitted facility. The rules are set by RCRA and, in many places, by stricter state programs.

Safe handling begins before disposal. Waste must be kept in compatible containers and segregated so that incompatible materials do not mix, for example acids away from cyanides or oxidizers away from solvents. Containers should be closed and kept in secondary containment where appropriate.

The SDS helps but does not make the decision. It often gives general disposal guidance only, because the final waste may be mixed with other materials or contaminated by use.