these definitions are unique, especially the definition of waste having the characteristic of toxicity.

1.   Ignitability. Ignitable materials are defined as having one or more of the following characteristics:

(a)  liquids that have a flash point of less than 60 °C (140 °F) or some other characteristic that has the potential to cause fire;

(b)  materials other than liquids that are capable, under standard temperature and pressure, of causing fire by friction, adsorption of moisture, or spontaneous chemical changes and, when ignited, burn so vigorously and persistently that they create a hazard;

(c)  flammable compressed gases, including those that form flammable mixtures;

(d)   oxidizers that stimulate combustion of organic materials.

Ignitable materials include most common organic solvents, gases such as hydrogen and hydrocarbons, and certain nitrate salts.

2.   Corrosivity. Corrosive liquids have a pH ≤ 2 or pH ≥ 12.5 or corrode certain grades of steel. Most common laboratory acids and bases are corrosive. Solid corrosives, such as sodium hydroxide pellets and powders, are not legally considered by RCRA to be corrosive. However, trained laboratory personnel must recognize that such materials are extremely dangerous to skin and eyes and must be handled accordingly.

3.   Reactivity. The reactivity classification includes substances that are unstable, react violently with water, detonate if exposed to some initiating source, or produce toxic gases. Alkali metals, peroxides and compounds that have peroxidized, and cyanide or sulfide compounds are classed as reactive.

4.   Toxicity. Toxicity is established through the toxicity characteristic leaching procedure (TCLP) test, which measures the tendency of certain toxic materials to be leached (extracted) from the waste material under circumstances assumed to reproduce conditions of a landfill. The TCLP list includes a relatively small number of industrially important toxic chemicals and is based on the leachate concentration, above which a waste is considered hazardous. Failure to pass the TCLP results in classification of a material as a toxic waste. The TCLP test is primarily for solid materials; liquids are typically evaluated on a straight concentration basis. TCLP analyses are usually performed by environmental testing laboratories.

8.B.3.2 Definition of Listed Waste

A chemical waste that does not exhibit one of the above characteristics may still be regulated if it is a listed waste. Although EPA has developed several lists of hazardous waste, three regulatory lists are of most interest to trained laboratory personnel:

   F list: waste from nonspecific sources (e.g., spent solvents and process or reaction waste);

   U list: hazardous waste (e.g., toxic laboratory chemicals); and

   P list: acutely hazardous waste [e.g., highly toxic laboratory chemicals, that is, chemicals having a lethal dose (LD50) of <50 mg/kg (oral, rat)].

Of the listed wastes, the most common for laboratories are the F wastes, which include many laboratory solvents. These include halogenated solvents (methylene chloride, tetrachloroethylene, and chlorinated fluorocarbons) and nonhalogenated solvents (xylene, acetone, ethyl acetate, ethyl benzene, ethyl ether, methyl isobutyl ketone, methanol, and n-butyl alcohol). Note that these are regulated under this listing only if they have been used (spent).

The other categories of listed waste common to laboratories are the U and P lists, which include many chemicals frequently found in laboratories. U and P lists pertain to

   waste chemicals that have not been used, because once used, the U or P listing does not apply;

   spills and spill cleanup material from U- or P-listed compounds; and

   rinsate from triple rinsing of empty containers of P compounds (described below), which is collected and handled as hazardous.

8.B.3.3 Determining the Regulatory Status of a Waste

The EPA regulations place the burden of determining whether a waste is regulated as hazardous and in what hazard classification it falls on the waste generator. Most laboratories rely on their EHS staff or their waste disposal firm to determine EPA and DOT regulatory categories (such as EPA ID numbers and transportation classes), as well as waste characterization information needed by the recycling, treatment, or disposal facility.

Testing is not necessarily required, and in most cases trained laboratory personnel are able to provide sufficient information about the waste to categorize it by general hazard categories. If the waste is not a common chemical with known characteristics, enough information about it must be supplied to satisfy the regulatory



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