Treatment and Disposal

Disposing of regulated medical waste (RMW) can be complex. RMW must be “disinfected” before it can be disposed of in a landfill. In this instance, “disinfected” means that the waste must be treated to destroy or kill infectious microoragnisms with a potential to cause disease. State health agencies often determine the level to which microorganisms must be undetectable.

This page reviews commonly available treatment technology options, outlines specific waste management challenges posed by the different types of medical waste, available waste treatment and disposal options, and indicates which options are particularly suitable for each waste type, from both a technical and a regulatory standpoint.

Treatment Technology Overview

The main task of an RMW treatment system is to render the waste non-infectious. A number of different treatment technologies are in use that achieve this aim. Historically, incineration was the method of choice for dealing with medical waste, and many hospitals burned their waste in on-site incinerators.

But as new science emerged, it gradually became clear that while healthcare facilities were using incineration to protect the public from infection, medical waste incinerators were exposing the public to emissions of a variety of toxic chemicals, including mercury, dioxins and furans, and other highly toxic substances. Pressure from public interest groups, and new, more stringent EPA standards for emissions from medical waste incinerators (1997) brought about the closure of several thousand on-site medical waste incinerators at healthcare facilities. Fewer than 110 healthcare facilities are still operating on-site medical waste incinerators, though a few centralized, commercial-scale incinerators continue to burn a large portion of medical waste. As hospitals have moved away from incineration due to its environmental and public health impacts, a range of technologies have emerged that disinfect medical waste effectively.

This section examines a range of available medical waste treatment and disposal options, and discusses some of the trade-offs associated with each technology.

Treatment Options

Currently available treatment technologies rely on two basic approaches to sterilization. Infectious organisms can be killed by subjecting them to excessive heat, or by bringing them into contact with chemical agents.

The most popular options include:

Heat:

steam autoclaves

microwave systems

dry heat and hot air systems

plasma arc

Chemical Agents:

chlorine compounds (including hypochlorite, chlorine dioxide)

ozone

alkali

other disinfectants (peracetic acid, glutaraldehyde, etc.—typically used for small batches)

Some systems use combinations of these treatments. Incinerators, for example, use both heat and a chemical reaction (oxidation by atmospheric oxygen). Another example is a system that operates at a relatively moderate temperature, which would otherwise leave the waste intact, but that uses alkali to liquefy the waste.

This does not exhaust the full range of theoretical possibilities. Radiation, for example, is an effective sterilization method that is used extensively on medical products, but is used only rarely for waste treatment. Systems using radiation for sterilization involve either radioactive sources (e.g. cobalt 60), with all the attendant risks and compliance obligations associated with handling them, or costly and energy-intensive equipment to generate the required intensity (e.g. for systems involving electron beams). The cost may be justifiable for high value-added products, but not for treating significant quantities of waste.

There is an additional important consideration relevant to the treatment of infectious waste. Whatever the lethal agent is, it can only be effective if it is applied in sufficient strength throughout the entire bulk of the waste. Either the treatment must be applied for a time sufficient to allow the agent to penetrate to the interior of the waste mass, or the waste must be shredded or ground up to bring the interior to the surface. Shredding or grinding the waste also has the advantage that it renders any recognizable body parts unrecognizable, as required in some states before disposal. It can also help reduce the volume of the waste. The disadvantage of including a shredding or grinding system is the cost and the additional maintenance required. Breaking up the waste before it has been rendered uninfectious also involves the risk of disseminating the pathogens, so shredding or grinding operations must be carried out in equipment specifically designed for medical waste processing.

The following pages highlight a few of the most significant points of comparison among the available treatment options. A more extensive discussion can be found in the publication Non-Incineration Medical Waste Treatment Technologies (August, 2001) from Health Care Without Harm.

Incineration

Thermal Treatment

Chemical Treatment

Treatment requirements for special types of RMW

Certain specific types of medical waste require special consideration when choosing a treatment technology. In this section, we will classify those types, indicate their special treament requirements, and show instances where different states have singled those waste types out with specific rules that apply to them.

There is no one “standard” classification scheme for medical wastes. The categories chosen to classify medical wastes will differ, depending on the purpose for which the wastes are being classified. Moving and storing wastes involves a different set of concerns from treating and disposing of them, for example. Another source of variation is differences among the regulations adopted by different states.

The classification scheme below is based specifically on considerations involved in treatment and disposal, and on the most common regulatory distinctions found in state regulations. See Types of Regulated Medical Waste for a more comprehensive overview of medical waste classification.

Types of RMW associated with elevated infection risk

The possibility of spreading infection is the primary concern associated with medical waste. Most microorganisms found in the environment are not particularly suited to colonizing humans, and most of the waste from healthcare facilities is no riskier than, say, typical household wastes. But three special categories of medical waste pose a particularly high risk of infectiousness:

Pathological Waste

Microbiological Waste

Sharps

Pathological Waste

Pathological Waste contains human tissue, organs, and fluids. Microorganisms that have become established in human tissues have already proved themselves capable of infecting humans, so it makes sense to apply extra precautions to handling this type of waste.

Some states, such as Arkansas, Connecticut, Delaware, Massachusetts, Maine, and Rhode Island, require either incineration or interment for pathological waste, apparently with no provision for exceptions. Other states allow alternative treatment methods, but spell out in detail which methods are allowed. For those state that do allow alternatives, steam sterilization (autoclaving) is the most common method indicated. A few states (e.g. Texas) also specifically provide for a broader range of thermal and chemical treatments for pathological waste. (See the table below for more specific links to paragraphs and sections in the state regulatory codes.)

A search of state regulations identified ten states that single out pathological waste for special treatment. Specific references to the relevant regulations, where available, are listed below. Check the State-by-State Regulated Medical Waste Regulations Locator for more information.

Microbiological Waste

Laboratory cultures (also called Microbiological Waste): This designation refers specifically to waste products from microbiology laboratories. It can pose a special hazard because it typically contains colonies of microorganisms that have been intentionally encouraged to grow under conditions conducive to their growth (generally for diagnostic purposes). Thus a greater concentration of organisms can be assumed to be present in these wastes than in general medical wastes. In addition, the organisms that have been cultured are often precisely those with infectious potential (which is why they are of interest to healthcare laboratories in the first place).

Most of the states that make special provisions for pathological waste (see above) also make special provisions for laboratory cultures.

Sharps

“Sharps” is a term applied to objects such as needles and scalpel blades. Their special hazard lies in the fact that, having been designed to pierce the skin, they are very efficient delivery mechanisms for putting infectious agents directly into the bloodstream. Wastes containing both infectious material and sharp objects create particular hazards for anyone handling them, or coming into contact with them.

There are basically two ways to address the risk of infection from sharps—mitigate the infectivity, or mitigate the sharpness. The first approach typically involves specifying treatment methods for sharps, often of the same level of stringency as those applied to pathological wastes. The second approach can involve isolating the sharps, generally in special containers, mechanically processing them, or encapsulating them. Many states spell out detailed regulations for sharps containers, including conditions to ensure that they are resistant to punctures, and that they are clearly labeled. Some states require that sharps be mechanically rendered non-sharp (using terms like “blunted” or “shredded”). Others require that they be rendered unrecognizable.

Sharps are singled out for special regulatory provisions by more states than any of the other medical waste categories. A search of state regulations identified the following specific references. Check the State-by-State Regulated Medical Waste Regulations Locator for more information.

Hazardous wastes

Certain materials have been singled out under federal law as being particularly dangerous to deal with and dispose of, and are included in a special regulatory category called “hazardous wastes”. (See Hazardous Materials for more background on these regulations). One provision of the hazardous waste rules, known as the “mixture rule”, specifies that if an otherwise non-hazardous waste is mixed with even a small amount of a “listed” hazardous waste, the mixture falls under all the restrictions that apply to hazardous wastes.

Mixtures of wastes which are simultaneously regulated medical wastes and hazardous wastes present special disposal challenges. Many hazardous waste haulers are not equipped to handle medical wastes. Few medical waste disposal facilities have permits to accept hazardous wastes.

The best course of action for a healthcare facility is to minimize the amount of this type of waste that it must deal with. (Of course, it may not be possible to eliminate mixed medical and hazardous waste entirely. For example, syringes and IV units that have been used to deliver certain chemotherapeutic agents may have to be treated as hazardous under some states’ rules.)

Some states use a different definition for mixtures, according to which a waste material only falls into the “hazardous” classification if the hazardous components are present in concentrations above some minimal threshold. When chemotherapy wastes can qualify for a “trace” classification, a facility may provide special containers, often colored yellow, for such “trace” wastes, so they are not mixed in with the hazardous wastes. It is important to use these containers appropriately. See the references under “Chemotherapy waste” in the More Resources section below, and consult the HERC Hazardous Waste State Resource Locator for links to additional information for your state.