Frequent Questions

Are there SW‐846 methods and regulatory levels for determining if cyanide and sulfide are reactive?

Are there specific SW‐846 methods for Reactive Cyanide and Reactive Sulfide? Also, is there a reactivity characteristic regulatory level for cyanide and sulfide?


There are multiple SW-846 methods for determining various cyanide and sulfide species. However, there are no specific methods currently available for reactive cyanide and reactive sulfide for reactivity characteristic determination. Such guidance and methods used to exist, including regulatory thresholds, but the methods were removed from SW-846 in 1998 due to a variety of issues (e.g., the tests worked well with pure compounds, but failed with waste mixtures such that results were very unreliable). Please see Chapter 7 of SW-846 for further discussion of the issue. 

You can also visit 40 CFR §261.23, which includes the 8 properties of waste that is hazardous due to the characteristic of reactivity. A waste is reactive hazardous waste if it exhibits one or more of these properties. The regulations do not require specific test methods for any of these properties, so generators must use their knowledge of the waste to make a determination. According to property (5) under 261.23, a waste is hazardous if it is a cyanide- or sulfide-bearing waste which generates toxic gases or vapors at a quantity sufficient to present a health danger.

In July 1985, EPA issued interim guidance describing certain threshold levels for cyanide- and sulfide-bearing wastes and laboratory methods for evaluating such wastes. In April 1998, EPA withdrew the July 1985 guidance. Therefore, EPA does not recommend use of the interim threshold levels of methods to determine if a waste is hazardous based on the characteristic of reactivity. EPA has removed the guidance threshold levels and the laboratory methods from Chapter Seven of SW-846. A copy of the EPA memorandum which withdrew the reactivity characteristic guidance can be found at$file/14177.pdf

The agency relies entirely on a descriptive definition of reactivity for cyanide and sulfide wastes, and depends on the generator's knowledge of their waste stream to classify it as a D003 waste, without the benefit of a characteristic test.

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