Air emissions standards and guidelines under the Clean Air Act for the incineration of hospital, medical, and infectious waste.

• Author: Reitze, Arnold W., Jr.

I. INTRODUCTION

Approximately 2400 hospital/medical/infectious waste incinerators (HMIWIs) operate in the United States, and they combust about 846,000 tons of hospital/medical/infectious waste (HMIW) each year.(1) The Environmental Protection Agency (EPA) estimated that there are approximately 1139 small, 692 medium, and 463 large HMIWIs, as well as 79 commercial HMIWIs.(2) These incinerators produce emissions of dioxins/ furans, particulate matter (PM), metals (cadmium, lead, and mercury), acid gases (HCl and [SO.sub.2]), and nitrogen oxides ([NO.sub.x]) that have the potential to harm human health and ecosystems when they are released into the air.(3)

In the 1990 Amendments to the Clean Air Act (CAA),(4) Congress included changes relating to air pollution emissions created by the combustion of solid waste in incinerators, including the burning of HMIW.(5) EPA attributed this congressional attention to two factors: the high level of public concern regarding incineration of municipal, medical, and other wastes and a concern over special management practices required to minimize air pollution from those sources.(6) Section 129 of the CAA directs EPA to regulate four categories of solid waste incineration units: municipal waste combustors (MWCs),(7) hospital/medical/infectious waste incinerators (HMIWIs),(8) industrial and commercial waste incinerators (ICWIs),(9) and other categories of solid waste incinerators (OSWIs).(10)

Hazardous waste incineration, another type of incineration, is regulated under the Resource Conservation and Recovery Act (RCRA), as amended, and by section 112 of the CAA.(11) Some HMIW is hazardous waste. Under existing law, hazardous wastes may be burned in hazardous waste incinerators (HWIs), boilers, or industrial furnaces.(12) Industrial furnaces include cement kilns and lightweight aggregate kilns (LWAKs).(13) HWIs reduce the volume or toxicity of hazardous waste but usually do not utilize the heat value of the waste or recover usable material to be recycled.(14) Hazardous wastes also have been burned on ships operating in the ocean, but EPA has essentially banned ocean incineration as a means of waste disposal in the United States.(15)

CAA section 129, added to the statute in 1990, requires EPA to establish new source performance standards (NSPS) under CAA section 111(d) for new solid waste combustion units and to establish emission guidelines under CAA section 111(d) for existing units.(16) When EPA did not promulgate regulations in a timely manner, it was sued by the Natural Resources Defense Council.(17) This led to a court-ordered deadline to promulgate an air toxics rule applicable to medical waste incinerators.(18) This Article will discuss the regulatory program applicable to incineration units combusting HMIW established by EPA in a final rule entitled "Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Hospital/Medical/Infectious Waste Incinerators,"(19) which was promulgated September 15, 1997.

II. BACKGROUND

1. Initial Awareness of the Problem and the Response by Congress

   Medical waste accounts for less than two percent of all municipal solid waste (MSW) produced in the United States(20) but its potential public health impact has made it a subject of concern.(21) In 1990, EPA estimated that about one million medical waste generators produce approximately four million tons of medical waste in the United States each year.(22) Of the four million tons of medical waste, infectious waste makes up approximately 465,600 tons, 359,000 tons of which is generated by hospitals.(23) About 7100 hospitals in the United States produce over three-fourths of the total volume of infectious waste,(24) but they make up slightly less than two percent of the total number of HMIW generators.(25) EPA attributed generation of the remaining twenty-three percent of infectious waste, by volume, to eight other types of infectious waste generators.(26)

   The medical profession has by necessity dealt with the safe and efficient management, treatment, and disposal of HMIW. However, the public did not become noticeably concerned with HMIW issues until the summers of 1987 and 1988 when medical waste of various types washed up on the beaches of the United States, primarily because of illegal disposal.(27) Some affected beaches were closed, and tourist-related beach businesses may have lost up to one billion dollars(28) Federal and state agencies, as well as many private groups, undertook studies or took other steps to address the problems of medical waste management.(29) Members of Congress, responding to the political pressure created by the public outcry over beach contamination, introduced numerous bills.(30) In November 1988 Congress passed the Medical Waste Tracking Act of 1988 (MWTA),(31) which became subchapter X of the Solid Waste Disposal Act (SWDA).(32)

   The MWTA provided for a two-year demonstration program to track medical waste from its creation to its disposal. EPA established a program that began June 22, 1989 and ended two years later. It applied to New York, New Jersey, Connecticut, Rhode Island, and Puerto Rico(33) and resulted in several reports.(34) In addition to this demonstration program, EPA gathered information on medical waste and developed a medical waste incinerator operator training course and manual.(35) Moreover, the Occupational Safety and Health Administration (OSHA) promulgated regulations concerning occupational exposure to bloodborne pathogens.(36) At the state level, more than eighty-four percent of the states developed regulations concerning medical waste.(37)

2. Methods of Hospital, Medical, and Infectious Waste Treatment

   1. In General

      In the first of two interim reports EPA was required to submit to Congress under the MWTA,(38) the Agency identified nine techniques, either existing or potentially available, for the treatment of HMIW: incineration, steam sterilization (autoclaving), gas sterilization, chemical disinfection with grinding, thermal inactivation, irradiation, microwave treatment, grinding and shredding, and compaction.(39) The Office of Technology Assessment has identified other potential treatment methods, including thermal destruction in molten glass furnaces, electrohydraulic disinfection, pulse-power technology, plasma torch technology, pyrolysis, electrocatalytic oxidation, steam sterilization combined with dry grinding and shredding, and thermal inactivation (dry heat sterilization) combined with shredding or compaction.(40)

      While the reports discuss high technology solutions to HMIW disposal, crude approaches are common. Noninfectious liquid medical waste may legally be poured down a drain leading to a sanitary sewer system, and some solid medical waste (e.g., pathological waste) may be disposed of by grinding and flushing it to a sanitary sewer system, assuming approval is obtained from the local sewer authority.(41) Infectious waste, typically considered a subset of medical waste, usually must be treated to render it noninfectious.(42) EPA estimates that ten to fifteen percent of medical waste is potentially infectious.(43) Ideally, treating infectious waste changes its pathogenicity so that it is incapable of transmitting disease.(44) EPA recommends that only treated infectious waste be landfilled.(45) If the state allows landfilling of infectious wastes, EPA recommends that such waste be placed only in well-controlled sanitary landfills.(46)

   2. Incineration

      Most noninfectious waste in the United States is disposed of directly into landfills without prior treatment. Most infectious medical waste is incinerated;(47) steam sterilization is the second most common treatment for infectious waste.(48) Most alternatives to incineration are conducted at the site where the medical waste is generated.(49) Incineration, on the other hand, may take place at the waste generation site or offsite at a commercial incinerator. The American Hospital Association reported in 1983 that sixty-seven percent of U.S. hospitals used onsite incinerators, sixteen percent used autoclaves (pressurized steam sterilization) followed by landfilling, and approximately fifteen percent used offsite treatment to dispose of their medical waste.(50) However, during the last few years many states have adopted stringent regulations limiting emissions from HMIWIs, and this has reduced the use of onsite incineration to manage medical waste.(51) EPA has stated that by the mid-1990s, less than half of the hospitals in the United States operated onsite medical waste incinerators.(52) Moreover, EPA estimates that more than ninety-five percent of other health care facilities such as nursing homes, outpatient clinics, and doctor and dentist offices no longer operate onsite medical waste incinerators.(53) Many medical waste generators have now switched to either onsite treatment by autoclaving or offsite treatment in large commercial incinerators typically dedicated to the treatment of medical waste.(54) Chemical treatment or microwave irradiation are also current commercially available options for the treatment of medical waste.(55)

      Incineration detoxifies and sterilizes medical waste.(56) Most incinerators in which medical waste is burned utilize two connected combustion chambers, the primary and the secondary.(57) Medical waste is loaded into the primary chamber where it is then ignited; most of the material is combusted, leaving ash, but volatile organic compounds (VOCs) that are not burned are driven into the secondary chamber where they are combusted.(58) Although most HMIWIs utilize this two-chamber combustion process, individual HMIWIs often differ from one another in design. After treatment, the ash from incineration--both bottom ash and the fly ash captured by air pollution controls--should be nonpathogenic and is typically disposed of by burial in a sanitary landfill.(59)

      Prior to the CAA's incinerator regulations going into...