What should you do with a container holding infectious waste that is leaking?

The prudent management of infectious laboratory waste requires the development of site-specific plans. Procedures developed by personnel within a facility will be appropriate for the specific needs of that facility and may gain a higher level of acceptance than will procedures imposed from outside sources. The process of developing a waste management plan is, in itself, acknowledgment of the need to accept responsibility for laboratory waste.

1. Basic Principles

Persons who generate infectious laboratory waste are responsible for preparing the waste so that potential occupational exposures and environmental contamination are minimized. Infectious waste needs to be segregated by the generator from other waste streams. This process will obviate the need for decision-making by support services personnel. The waste can then be treated on-site to reduce the concentration of the pathogen to an acceptable level (decontamination), or packaged in a way to prevent subsequent exposure of other persons having to handle the waste prior to terminal treatment. Packages of infectious waste need to be identified so that the potential hazard clearly can be recognized and understood by others. The universal biohazard symbol is used for this purpose.

2. Containment

A variety of packaging items for containment and transport of infectious waste are available. Infectious waste containers serve as primary barriers to protect the worker and to minimize the chance of environmental contamination (). Typically, these containers are made from leak-resistant paper or cardboard, stainless steel, or temperature-resistant polymers. The nature and volume of the waste, the terminal treatment method, and their costs are principal factors to consider in the selection of the mode of packaging.

FIGURE 4.1

Biohazardous waste should be segregated from other types of waste prior to its disposal. Courtesy, National Institutes of Health.

Solid waste can be packaged safely in sturdy bags or boxes. Flat trays with sealable lids are suitable for containing pipettes and other laboratory supplies during decontamination. Bulk liquids may be collected in leak-proof containers, decontaminated, and then safely discharged into the sewer system. Rigid, puncture-resistant, sealable containers are necessary for packaging "sharps," e.g., broken glass, brittle plasticware, needles, and scalpel blades. Wet waste should be packaged with sufficient absorbent materials to contain residual liquids and to minimize leakage. In packaging wet materials for transport, it is prudent to double-bag the waste, sealing each bag independently. Heavy waste such as anatomical specimens, animal bedding, and laboratory specimens need to be placed in rigid containers. Care must be taken that the weight of the waste load does not exceed the burst strength of the container.

The physical properties of the container should be compatible with the treatment process. Waste placed in stainless steel pans, waxed-lined paper bags, tempered glass, and heat-resistant plastics can all be safely processed in an autoclave. Metal containers have been shown to enhance the transfer of heat to the waste load during autoclaving, whereas containers made of plastic retard steam penetration. Processing smaller waste loads and extending the treatment period can compensate for this feature of plastic containers.

Most chemical disinfectants have no appreciable effect on high-strength plastics at room temperature, but may be corrosive to metals. Liquid infectious waste often is stored in plastic carboys designed for chemical disinfection. Metal receptacles can be autoclaved and recycled but are not suitable for incineration. Ideally, waste should be packaged in disposable receptacles that minimize handling of the waste and are suitable for the waste stream treatment method. Cleaning containers that are to be reused is labor intensive and increases the risk of occupational injuries and exposures to biohazards.

3. Personal Protection

The most important precautions for all personnel handling infectious waste are the wearing of protective gloves and frequent handwashing. Gloves and a laboratory coat are recommended for all activities involving manipulations of contaminated items. Gloves and clothing should be changed when soiled or damaged. Thorough handwashing is recommended after working with infectious materials. Scavenging through waste, as well as eating, drinking, and smoking while working with waste, must be prohibited.

The type of laboratory activity will determine if there is a need for additional protective measures. Laboratory activities with a high probability of contamination caused by spills of infectious fluids, or the production of droplets, should be performed on plastic-backed absorbent bench paper. Workers who process infectious waste in an autoclave should wear a rubber apron, sturdy shoes, asbestos-free heat-resistant gloves, and a face shield, to protect against accidents that may occur while loading or unloading the autoclave.

4. Chemical Decontamination

Liquid and gaseous chemicals are used routinely for decontaminating infectious waste. summarizes use parameters and applications for chemical decontamination of specific types of frequently generated infectious waste from laboratories[140 ]. Some examples of these applications are as follows:

TABLE 4.1

Decontaminants and Their Use in Infectious Waste Management.

• Use of an intermediate decontamination step during the storage or transport of waste, e.g., the addition of liquid chlorine bleach, iodophors, or phenolic disinfectants to pipette discard pans at work stations. The concentration of decontaminant for this use should be such that the addition of liquid waste will not interfere with its effectiveness.

• Gaseous decontamination of HEPA filters in biological safety cabinets. This procedure should be carried out prior to removal of the filter for replacement or prior to repairing the cabinet. Decontamination is usually carried out with formaldehyde sublimed by heat from paraformaldehyde flakes in the presence of high humidity. The cabinet must be sealed with plastic sheets and tape prior to initiating decontamination. Human contact with the formaldehyde should be prevented because of the highly irritating, toxic, and possibly carcinogenic properties of the gas (the OSHA limit for permissible exposure is 2 ppm). A detailed description of the method is available[95 ].

• Decontamination of large items of equipment that are to be removed from the laboratory for repair or discard. Care should be taken to avoid corrosion of sensitive parts if the equipment is to be reused rather than discarded. A disinfectant that has low corrosive properties and has been proven to be effective against the specific microorganism should be used for this purpose.

• Treatment of mixed hazardous waste such as combinations of infectious agents and radioisotopes. After an appropriate assessment of the waste, it may be prudent to use chemically compatible decontaminants to avoid the release of potentially hazardous emissions. See the section on mixed waste (Chapter 4, Section F, Part 1) for a more detailed discussion of such problems.

5. Steam Autoclaving

Steam autoclaving usually is considered to be the method of choice for decontaminating cultures, laboratory glassware, pipettes, syringes, or other small items known to be contaminated with infectious agents. Location of the autoclave within the laboratory minimizes storage and transport problems. It provides a technically proved treatment method for rendering infectious material safe. Autoclaved waste can be disposed of as general waste.

Certain waste materials are difficult to decontaminate in the autoclave because they insulate and protect the contaminating organisms from heat and steam penetration. Examples include animal carcasses, human body parts, and large volumes of contaminated clothing. The preferred method for decontamination of animal remains and human body parts is incineration. Routine laundering is appropriate for clothing contaminated with all but the most hazardous infectious agents. Autoclaving is not the recommended method for decontaminating very large volumes of waste because the time required for processing is too long, and the chamber size is usually too small. The lack of volume reduction and the failure of the autoclave process to render body parts unrecognizable are also limitations to this process.

Operational considerations based on specific load conditions are very important to ensure adequate decontamination in autoclaves. Most laboratories have gravity displacement autoclaves, which operate at 121°C (15 lbs/in2 of pressure). Because of the high levels of organic matter normally associated with infectious waste, these types of autoclaves should be operated for a minimum of 60 minutes. Some laboratories may have vacuum-type autoclaves, which operate at 132°C (27 lbs/in2 of pressure). It is recommended that these autoclaves be operated for a minimum of 10 minutes. The shorter time period for this type of autoclave is due to the higher temperatures and pressures attainable with the vacuum cycle and the more effective penetration of steam.

It may be desirable to add water to a load of waste to be decontaminated in an autoclave to facilitate steam formation and penetration, as well as to avoid the collection of residues on reusable items that may be difficult to remove in subsequent cleaning processes. Caution is essential while adding water to a load, to minimize the potential for aerosolizing infectious agents in the waste. Drain lines from steam autoclaves can be connected to the sanitary sewer except for those installed in maximum containment laboratories (Biosafety Level 4).

When loads contain both reusable and disposable items, the material should be separated to prevent melted plastic from encapsulating items to be reused.

6. Incineration

Incineration is the method of choice for treating large volumes of infectious waste, animal carcasses, and contaminated bedding materials. Because incinerators usually are located some distance from the laboratory, additional precautions for handling and packaging of infectious waste are necessary.

Incinerators require approval and permits from local and state pollution control authorities. Although the initial capital costs and maintenance costs are high, incineration offers many advantages as a method for the treatment of infectious waste[16 ][49 ]. Incineration significantly reduces waste volume and produces an unobjectionable end-product, ash. Proper design and operation can provide for energy (heat) recovery, making the operation more economical[25 ].

Although specific operating standards have not been set for the incineration of infectious or pathological waste, the principles of effective combustion are well understood. Waste and the hot gaseous products of its volatilization should be retained in the combustion chamber(s) for a long enough time and at a high enough temperature to allow for mixing (turbulence) with excess oxygen, so that the combustion reactions can go to completion. A deficiency in any one or more of these critical combustion parameters can result in smoke or odor production, excessive emissions of harmful gaseous by products, and the discharge of incompletely burned waste residue.

Many modern incinerators achieve the proper conditions for complete and effective combustion by providing secondary combustion chambers or zones with burners to ensure that adequate conditions for time, temperature, and mixing are achieved. Primary combustion temperatures of at least 1600°F with good mixing and a gaseous retention time of about 2 seconds should provide for good burnout for the waste described in this chapter. All pathogens and proteinaceous materials are denatured at temperatures well below that just cited[49 ].

Complete combustion also is dependent on correct operation of the equipment. The operator of the incinerator should be careful to avoid overfeeding with waste materials. Too much raw waste in the primary combustion chamber can overwhelm the combustion zones with more volatile products than the equipment is designed to handle within a fixed gas retention time. The result of overfeeding will be smoke and odors. Overfeeding an incinerator also can result in the bottom ash being moved though the primary chamber too quickly, and consequently being discharged before complete burnout takes place.

Another condition that can result in incomplete burnout of the bottom ash (uncombusted feed material) is the lack of tumbling of the solid waste feed pile in the primary chamber. This is a common condition developing in top-fed incinerators where waste continually is fed directly on top of the existing pile of previously loaded waste materials. In this situation an outer layer of insulating ash can form that retards combustion of the contents in the center of the pile. To achieve complete residue burnout, provisions should be made to agitate or break up the pile periodically. This can be done mechanically with an oxygen pulse or manually with a rake.

In selecting a new incinerator for a facility, it is critical that the actual waste stream to be treated be characterized. Too often in the past the term ''pathological waste" has been used to determine the size of an incinerator. True pathological waste consists of animal tissue that is quite wet and has an approximate heat content of 1000 BTU/lb (555.6 kcal/kg). Infectious waste incinerators should burn a wide variety of materials including significant amounts of paper and plastics as well as pathological waste. The effective heat content of the actual waste mix usually will be well above 1000 BTU/lb. Only by knowing the specific composition of the facility's waste stream can a vendor properly size the unit.

In summary, safe, effective incineration can be achieved by (1) proper equipment design; (2) provision for the time, temperature, turbulence, and air required for complete oxidation; and (3) careful feeding of the unit. To assist the laboratory manager in the selection of equipment, a consultant knowledgeable in the field of incineration should be retained to help develop a site-specific procurement specification[49 ].

7. Validation of Decontamination Methods

Sterility testing or testing for survival of an indicator microorganism is neither applicable nor practical to verify the adequacy of the treatment of infectious waste, since sterility is not an objective of decontamination methods, and indicator microorganisms do not simulate typical waste load composition. Rather, precise reproduction of each of the conditions (operational parameters) prescribed for the different treatment methods should be relied upon to ensure adequate treatment each time waste is processed. This reliance, however, is justifiable only if all of the measuring devices used to monitor the treatment process (e.g., thermometers, pressure gauges, and timing mechanisms) are functioning properly. It is imperative that the accuracy of these measuring devices be certified independently by the user, after the equipment is first installed and before any waste is treated, and again thereafter at regularly scheduled intervals (at least annually). This process should be repeated after maintenance work or repairs are carried out, and if the equipment is relocated.

Each of the different treatment methods for infectious laboratory waste requires a different set of conditions to be effective. Effective autoclaving is dependent upon time, temperature, and steam penetration, whereas effective incineration is dependent upon time, temperature, and turbulence. Chemical decontamination is dependent upon several parameters, including selection of an effective chemical, contact time, concentration, and the presence of organic materials or other interfering substances. Operator controls include such matters as procedures for packaging the waste, placement of the load, feed rate, and—perhaps most important—the keeping of an accurate record of the operational parameters achieved for each load processed. Detailed information regarding the principles of efficacious treatment is available[48 ][49 ][52 ][75 ][111 ][140 ].

Chemical indicators are of limited value in verifying the decontamination of infectious waste. Chemical indicator inks printed on waste packaging materials intended for autoclaving provide a color change that serves only to distinguish treated waste from waste requiring treatment: i.e., failure of an indicator to change to its signal color after the process demonstrates immediately that the equipment has malfunctioned.

What characteristics should safe containers have quizlet?

Which of the following are examples of regulated waste quizlet?

Which of the following is an example of a moving machine part with hazardous motions?

Who is responsible for good housekeeping in the workplace quizlet?