When is waste considered hazardous or toxic?

When it has any of the following 3 characteristics, and is not specifically excluded from regulations 10 CFR 261-4: 
Ignitability: A flash point of less than 140 degrees Fahrenheit (60 degrees Celsius).
Corrosivity: A pH less than or equal to 2.0; more than or equal to 12.5; or corrodes steel at a rate greater than 6.35 mm/year at 55 degrees Celsius.
Reactivity: Unstable; reacts violently or forms potentially explosive mixtures when coming in contact with water; is sufficiently cyanide or sulfide bearing to produce toxic gas; is capable of detonation.