Pursuant to a congressional request, GAO provided information on the: (1) differences between hazardous waste incinerators that have received permits under the Resource Conservation and Recovery Act (RCRA) of 1976 and those that are allowed to operate for some limited period of time without a permit; and (2) emissions standards in effect for incinerators during and after a particular hazardous waste incinerator was in operation.

GAO found that: (1) permitted incinerators must conduct trial burns that meet performance standards, while interim-status incinerators are not generally required to do so; (2) permitted incinerators must continuously monitor operating conditions and maintain extensive monitoring records, while interim-status incinerators are not required to maintain monitoring records; (3) permitted incinerators must meet waste analysis requirements that are more specific and extensive than those for interim-status incinerators; and (4) permitted incinerators must store hazardous waste containers in a containment system, while interim-status incinerators are not required to do so. GAO also found that: (1) six incinerators continue to operate under interim status; (2) proper implementation of the permit regulations by facilities should provide more human health and environmental protection than those being provided by the interim-status regulations; and (3) during the years the hazardous waste incinerator was in operation, the Environmental Protection Agency (EPA) had set only 8 hazardous emissions standards, but the Clean Air Act Amendments of 1990 have since established a list of 190 toxic air pollutants for regulation and a 10-year schedule for EPA to set standards for those pollutants.