Medical waste treatment and disposal presents a continuing problem to hospitals. Increasingly stringent regulations limit did disposal options. Costs and liabilities escalate. Hospitals are attempting to gain control over both costs and liability by seeking alternative on-site solutions to their medical waste disposal problems.
Making the proper waste disposal decision, however, requires that each hospital consider all the factors influencing treatment and disposal alternatives.
Medical wastes are a part of the total solid waste stream generated by the facility. As such, any potential option must be evaluated as an integral part of the hospital's total solid waste management plan.
Congress is amending the Resource Conservation and Recovery Act to incorporate this philosophy of integrated solid waste management.
A part of this philosophy is to investigate and implement mechanisms that encourage waste minimization through prudent purchasing decisions, process revisions, recycling and reclamation. However, even with the best of all waste minimization programs, wastes will be generated that still require treatment and/or disposal.
Infectious medical wastes would be included in this category. As proposed in Senate Bill 976, language directs the Environmental Protection Agency (EPA) to promulgate regulations for the management of medical wastes at the national level.
Although it allows the EPA to determine parameters for medical waste treatment and disposal, this language provides an indication of what may be expected of medical waste treatment options for hospitals in the near future.
Proposed Senate language is nonprescriptive, allowing incineration, steam sterilization, chemical disinifection, and other alternate treatments for medical wastes. However, for these methods, the proposed language sets criteria to ensure the treatment or disposal method is effective.
Incineration
Incineration of medical waste has been traditionally viewed as the most efficient method for both treatment and destruction. However, more stringent emission standards and general public opposition to incineration have combined to make incineration more difficult to carry out, largely because of the required permits.
Incinerators designed to meet anticipated emission standards via internal design and/or pollution control equipment are too expensive for many smaller and mid-sized hospitals to build or operate. Hospitals not only have to meet emission requirements; some states require public hearings before permits are granted.
If these cost and permit obstacles can be overcome, incineration is the best disposal option available. Waste volumes are reduced by 90% to 95% to residual ash, which is typically regulated as a general or special waste.
The incinerator, if sized properly, also can destroy the majority of general solid wastes generated by the hospital. Plus, energy recovery may be applicable under certain circumstances. The use of on-site incineration can substantially reduce the hospital's dependence on landfilling and minimize the liability associated with offsite disposal of infectious waste.
Within the proposed Senate language, incineration technology has been limited to controlled-air, multi-chambered incinerators. These incinerators must meet criteria that:
(1) effectively destroys all categories of medical wastes, and effectively kills live and dormant forms of pathogenic organisms;
(2) meets emission standards at least as stringent as those established pursuant to section 129 of the Clean Air Act (notably particulate, hydrochloric acid, carbon monoxide, sulphur oxides, nitrogen lead, cadmium, mercury, and dioxins); and
(3) prevents the rupture of containers during loading operations.
The medical waste incinerator standards, legislated under the Clean Air Act Amendments of 1990 will be promulgated by November 1992, with enforcement of the standards no more than six months after the date of promulgation. Those performance standards issued by the EPA by legislative directive will include subsections on (1) emission limitations; (2) monitoring: and (3) operator training.
Steam Sterilization
As an alternative to incineration, steam sterilization (autoclaving) places first as a medical waste treatment option. Decontamination by steam sterilization depends on time and temperature, and is determined by the minimum time required to kill bacillus stearothermophillus spores exposed to saturated steam (wet heat) at a particular temperature.
The degree of steam penetration is often the limiting factor in achieving sterilization within a reasonable time. Decontamination is primarily accomplished through heat transfer by direct steam contact with the microorganism, or secondarily through heat transfer by conduction.
Heat transfer through direct steam contact is essentially instantaneous, while heat transfer by conduction is relatively slow. The degree of steam penetration through the waste load, therefore, has a direct influence on the time it takes to achieve sterilization.
Factors such as load density, containment barriers and load configuration must be considered to ensure rapid and effective decontamination.
Infectious wastes most suited for steam sterilization are those with a relatively low density and low-to-moderate water content. Contaminated plastic single-use items and cellulose products are easy to decontaminate, provided that they are not packed tightly or encased so that steam penetration is hindered. Conversely, materials such as body tissue, parts, and fluids are relatively dense and are high in water content, inhibiting the amount of heat directly transferred by steam contact.
Proposed Senate language states that for steam sterilization the following criteria must be met by a hospital to demonstrate effectiveness of the process:
(1) "demonstrate that all pathogenic organisms are rendered harmless";
(2) "must provide quality assurance programs";
(3) "provide for periodic testing using biological indicators that demonstrate proper sterilization of the waste stream";
(4) "provide for labeling that clearly distinguishes treated from untreated waste";
(5) "provide for loading parameters that ensure consistent and adequate steam and heat penetration to each load."
A problem facing all steam sterilizers is that of waste being recognizable after the sterilization process. Although this was not of major concern in the past to haulers, landfill operators and regulators, it is now a priority issue. Infectious waste presents not only the problem of an infectious nature, but of an emotional one as well.
Many of the items listed as regulated medical wastes in the Medical Waste Tracking Act of 1988 were included on the basis of recognizability more than on potential infectivity.
Regulatory positioning by the EPA (1989) in the now-expired EPA "Standards for the Tracking and Management of Regulated Medical Wastes" stated that to avoid the tracking standards (e.g., segregating labeling, manifesting, etc.) imposed on regulated medical waste, the waste must be destroyed.
This same philosophy is echoed in the proposed Senate language that states that medical wastes once treated and in which treatment is in conformance with the guidelines "shall not be considered medical wastes expect that pathological wastes, sharps and contaminated animal carcasses must be rendered unrecognizable."
Alternate treatment technologies
Added costs and permits required for incinerators, coupled with the limitations of steam sterilization, have created the momentum for new on-site medical waste treatment technologies to be developed. These technologies can be categorized into two groups: (1) chemical disinfection and grinding and (2) wet heat disinfection/sterilization via non-ionizing radiation (e.g., microwaving).
As with steam sterilization, these alternatives also have their limitations. Beyond capacity or waste-type limitations, however, is the fundamental need to make sure the treatment process employed is effective. To date, no criteria have been universally established that demonstrates and compares relative treatment effectiveness.
To provide criteria for treatment effectiveness, proposed Senate language directs the EPA to "establish a process for approval and certification of treatment technologies capable of rendering medical waste harmless." To establish a "level playing field" on which all treatment technologles must conform will require the adoption of, or reference to, nationally recogulzed methods or standards that specify conditions and biological indicators to judge the process effectively.
Depending on the treatment process tested, these conditions will define the parameters of the testing procedures and the concentrations and amounts of the heat-, radiation-or chemical-resistant biological indicators required.
At a mininimum, testing criteria should delineate specific testing parameters that must be met to ensure complete decontamination. These criteria should include verification of a specified log-reduction of a specific heat-, radiation-or chemical-resistant microorganism under standard operating conditions (e.g., time, temperature, load densities).
In the absence of established effectiveness criteria, I advise hospitals to be skeptical of the manufacturer's claims for alternative treatment processes. Use the following questions as a guide in the decision-making process:
* Has the process been approved by the state?
* What permits are required by the state or local governments?
* What evidence has been supplied by the manufacturer to ensure effective treatment and operator safety?
* What categories of medical waste will the equipment effectively treat or handle?
* Does the equipment meet the capacity requirements for the waste volumes generated?
* For those categories of waste that can't be treated, what further segregation and other disposal methods will be required and at what costs?
* What are the capital equipment, utility, supply, maintenance and labor costs required to operate the equipment?
* What are the space requirements (including structural support, traffic patterns, field or electrical requirements)?
Each treatment and disposal option should be evaluated in terms of state and local regulations, the effectiveness of the treatment process, and the safety features provided to protect the operator from chemical, biological or physical hazards.
Criteria for selecting waste treatment systems
* Has the process been approved by the state?
* What permits are required by the state or local governments?
* What evidence has been supplied by the manufacturer to ensure effective treatment and operator safety?
* What categories of medical waste will the equipment effectively treat or handle?
* Does the equipment meet the capacity requirements for the waste volumes generated?
* For those categories that can't be treated, what further segregation and other disposal methods will be required and at what costs?
* What are the capital equipment, utility, supply, maintenance, and labor costs required to operate the equipment?
* What are the space requirements (including structural support, traffic patterns, field or electrical requirements)?
