HAZARDOUS
WASTE DISPOSAL
Hospitals generate large
amounts of diverse wastes that require disposal. Much of the waste is hazardous
and must therefore be packaged, transferred, and disposed of properly to
protect both the persons handling it and the environment.
Hospital wastes can be
categorized as infectious or noninfectious. Infectious wastes include human,
animal, or biological wastes and any items that may be contaminated with
pathogens. Noninfectious wastes include toxic chemicals, cytotoxic drugs, and
radioactive, flammable, and explosive wastes.
INFECTIOUS
WASTES
The material in this
section is extracted from the EPA guide for Infectious Waste Management
(EPA 1986). The following publications are also recommended:
·
Guideline
for Handwashing and Hospital Environmental Control Section 4 (Garner and Favero 1985). This
document reprinted in Append 8.
·
Guideline
for Isolation Precautions in Hospitals (Garner and Simmons 1983). This document is
reprinted in Appendix 8.
·
Waste
Disposal in Microbiology Laboratories, Chapter 9 (Mackel and Mallison 1981).
Infectious Waste
Management Plan
Compliance with State and
local regulations should be carefully considered when developing an infectious
waste treatment plan. Each hospital should develop an infectious waste
treatment plan. Each hospital should develop an infectious waste management
plan that provides for (1) Designation of the waste that should be managed as
infectious, (2) Segregation of infectious waste from the noninfectious waste,
(3) Packaging, (4) Storage, (5) Treatment, (6) Disposal, (7) Contingency
measures for emergency situations, and (8) Staff training.
Types of Infectious
Waste
Infectious wastes may be
classified as isolation wastes, cultures and stocks of infectious agents and
associated biologicals, human blood and blood products, pathological wastes,
contaminated sharps, contaminated carcasses, body parts, and bedding, or
miscellaneous contaminated wastes. Each of these categories is discussed
briefly as follows:
·
Isolation
wastes are those
generated by patients who are isolated because of communicable diseases.
·
Cultures
and stocks of infectious agents and associated biologicals include specimen cultures from
medical and pathological laboratories, cultures and stocks of infectious agents
from research and industrial laboratories, wastes from the production of
biologicals, discarded live and attenuated vaccines, and culture dishes and
devices used to transfer, inoculate, and mix cultures.
·
Human
blood and blood products include blood as well as serum, plasma, and other blood products.
·
Pathological
wastes include
tissues, organs, body parts, and body fluids that are removed during surgery
and autopsy.
·
Contaminated
sharps are
hypodermic needles syringes, Pasteur pipettes, broken glass, and scalpel
blades. These items should be considered infectious wastes because of the
possibility of contamination with blood-borne pathogens.
·
Contaminated
carcasses, body parts, and bedding emanate from animals intentionally exposed to pathogens during
research, the production of biologicals, or the in vivo testing of
pharmaceuticals.
·
Miscellaneous
wastes that are not
designated as infectious should be assumed to be infectious and should be
managed as such to maintain consistent levels of protection for both the
environment and for persons handling these wastes. Miscellaneous wastes include
those from surgery and autopsies, contaminated laboratory wastes, dialysis unit
wastes, and contaminated equipment.
o
Wastes
from surgery and autopsies include soiled dressings, sponges, drapes, lavage tubes, drainage sets,
underpads, and surgical gloves.
o
Contaminated
laboratory wastes
include specimen containers, slides and cover slips, disposable gloves,
laboratory coats, and aprons.
o
Dialysis
unit wastes include
contaminated disposable equipment and supplies such as tubing, filters,
disposable sheets, towels, gloves, aprons, and laboratory coats.
o
Contaminated
equipment refers to
discarded equipment and parts that are used in patient care, medical and
industrial laboratories, research, and the production and testing of certain
pharmaceuticals.
Treatment and Disposal
Methods
Several methods are used
for infectious waste treatment, depending on the type of waste material. These
treatment methods include steam sterilization, incineration, thermal inactivation,
gas/vapor sterilization, chemical disinfection, and sterilization by
irradiation. After treatment, the wastes or their ashes can be disposed of by
discharge into sanitary sewer systems (for liquid or ground-up waste) or burial
in sanitary landfills. Acceptable treatment methods for the various types of
wastes are listed in Table 6-1.
Table
6-1. Recommended techniques for treatment of infectious wastes*
|
Type of
infectious waste |
Recommended treatment techniques† |
||||
|
Steam |
Incineration |
Thermal |
Chemical |
Other |
|
|
Isolation
wastes |
X |
X |
|
|
|
|
Cultures
and stocks of infectious agents and associated biologicals |
X |
X |
X |
X |
|
|
Human
blood and blood products |
X |
X |
|
X |
X** |
|
Pathological
wastes |
X†† |
X |
|
|
X§§ |
|
Contaminated
sharps |
X |
X |
|
|
|
|
Contaminated
animal wastes: |
|
||||
|
Carcases and parts |
X†† |
X |
|
|
|
|
Bedding |
|
X |
|
|
|
*Taken from EPA (1986).
†The recommended treatment
techniques are tose that are most appropriate and are generally in common
use; an alternative teatment technique may be used to treat infectious waste
if it provides effective treatment §Chemical disinfection is
most appropriate for liquids. **Discharge to the sanitary sewer for treatment in
the municipal sewage system (provided that secondary treatment is available). ††For aesthetic reasons, steam
sterilization should be followed by incineration of the treated waste or by
grinding with subsequent flushing to the sewer system in accordance with
State and local regulations. §§Handling by a mortician
(burial or cremation). |
|||||
Steam Sterilization,
Autoclaving
Steam sterilization,
autoclaving, involves the use of saturated steam within a pressure vessel at
temperatures high enough to kill infectious agents in the waste. Sterilization
is accomplished primarily by steam penetration. Steam sterilization is most effective
with low-density material such as plastics. An alternative treatment method,
e.g. incineration, should be used on high-density wastes such as large body
parts or large quantities of animal bedding or fluids because they inhibit
direct steam penetration and require longer sterilization times.
Containers that can be used
effectively in steam sterilization are plastic bags, metal pans, bottles, and
flasks. High-density polyethylene and polypropylene plastic should not be used
in this process because they do not facilitate steam penetration to the waste
load. Heat-labile plastic bags allow steam penetration of the waste, but they
may crumble and melt. If heat-labile plastic bags are used, they should be
placed in another heat-stable container that allows steam penetration, such as
a strong paper bag, or they should be treated with gas/vapor sterilization.
The following precautions
should be taken when using steam sterilization:
·
Plastic
bags should be placed in a rigid container before steam treatment to prevent
spillage and drain clogging.
·
To
facilitate steam penetration, bags should be opened and caps and stoppers
should be loosened immediately before they are placed in the steam sterilizer.
·
Care
should be taken to separate infectious wastes from other hazardous wastes.
The following precautions
should be taken when using steam sterilization:
·
Plastic
bags should be placed in a rigid container before steam treatment to prevent
spillage and drain clogging.
·
To
facilitate steam penetration, bags should be opened and caps and stoppers
should be loosened immediately before they are place in the steam sterilizer.
·
Care
should be taken to separate infectious wastes from other hazardous wastes.
·
Infectious
waste that contains noninfectious hazards (see Section 5) should not be
steam-sterilized because of the possibility that the equipment operator will be
exposed to toxic, radioactive, or other hazardous chemicals.
·
Waste
that contains antineoplastic drugs, toxic chemicals, or chemicals that would be
volatilized by steam should not be steam-sterilized.
·
Persons
involved in steam sterilizing should be trained in handling techniques to
minimize personal exposure to hazards from these wastes. Some of these techniques
include:
o
Use of
protective equipment
o
Minimization
of aerosol formation
o
Prevention
of waste spillage during autoclave loading and unloading
o
Prevention
of burns from handling hot containers
o
Management
of spills
·
The
autoclave temperature should be checked with a recording thermometer to ensure
that the proper temperature is being maintained for a long enough period during
the cycle.
·
Steam
sterilizers should be routinely inspected and serviced, and the process should
be routinely monitored to ensure that the equipment is functioning properly.
Incineration
Incineration converts
combustible materials into noncombustible residue or ash. Gases are ventilated
through the incinerator stacks, and the residue or ash is disposed of in a
sanitary landfill. If incinerators are properly designed, maintained, and
operated, they are effective in killing organisms present in infectious waste. Although
all types of infectious waste can be disposed of by incineration, the process
is especially useful for anesthetic disposal of pathological wastes such as
tissues and body parts. Incineration also renders contaminated sharps unusable.
The principal factors to consider when incinerating infectious wastes are
variations in waste composition, the waste feed rate, and the combustion
temperature. Infectious wastes containing antineoplastic drugs should be
disposed of in an incinerator that provides high temperatures and enough time
for the complete destruction of these compounds. The incinerator’s
effectiveness in disposing of chemical wastes should be documented before such
use.
Thermal Inactivation
Thermal inactivation
involves the treatment of waste with high temperatures to eliminate the
presence of infectious agents. This method is usually used for large volumes of
infectious waste. Liquid waste is collected in a vessel and heated by heat
exchangers or a steam jacket surround the vessel. The types of pathogens in the
waste determine the temperature and duration of treatment. After treatment, the
contents can be discharged into the sewer in a manner that complies with State,
Federal, and local requirements. Solid infectious waste is treated with dry
heat in an oven, which is usually electric. This method requires higher
temperatures and longer treatment cycles than steam treatment.
Gas/Vapor Sterilization
Gas/vapor sterilization
uses gaseous or vaporized chemicals as the sterilizing agents. Ethylene oxide
is the most commonly used agent, but should be used with caution since it is a
suspected human carcinogen, see sec 5 for a discussion of ethylene oxide
toxicity and work practices. Because ethylene oxide may be adsorbed on the
surface of treated materials, the potential exists for worker exposure when
sterilized materials are handled.
Chemical Disinfection
Chemical disinfection is
the preferred treatment for liquid infectious wastes, but it can also be used
in treating solid infectious waste. The following factors should be considered
when using chemical disinfection:
·
Type
of microorganism
·
Degree
of contamination
·
Amount
of proteinaceous material present
·
Type
of disinfectant
·
Contact
time
·
Other
relevant factors such as temperature, pH, mixing requirements, and the biology
of the microorganism
Ultimate disposal of
chemically treated waste should be in accordance with State and local
requirements.
Sterilization by
irradiation
Sterilization by
irradiation is an emerging technology that uses ionizing radiation. Advantages
over other treatment methods are as follows:
·
Electricity
requirements are nominal.
·
Steam
is not required.
·
No
heat or chemicals remain the treated waste.
The principal disadvantages
are as follows:
·
Capital
costs are high.
·
Highly
trained operating and support personnel are required.
·
Space
requirements are great.
·
The
potential exists for worker exposure as a result of leaks in seals or poor work
practices.
·
Ultimate
disposal of the radiation source may pose problems.
This page was last updated: April 28, 1998