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Biological Waste Disposal
• Contaminated media and culture vessels (Petri dishes, inoculating loops) and
personal protective equipment (PPE), such as disposable gloves
• Blood and other bodily or biological fluids
• Sharps and broken glass, including needles, razor or dissecting blades, glass
pipets and glass tubing
HAZARDS
It is prudent practice to treat all microbial cultures and contaminated materials as if
they may cause infection or pose an environmental risk if released. Microorganisms
cultured directly from the environment should NOT be incubated at temperatures
higher than 25 °C, and cultures should not be opened after they have been plated
on agar. After incubation, a single microbial cell may multiply to more than one
million, and at that level may present a risk if a culture is broken or carelessly
handled. Universal precautions for microbiological wastes, biological fluids and
contaminated labware include autoclaving, dry-heat sterilization or chemical
disinfection.
Disposal Procedure
Sterilization is defined as the death of all living organisms, including spores, in or
on an object. Chemical disinfection with diluted household bleach is effective at
killing bacteria, fungi and algae, including bacterial spores and viruses. The required
concentrations and time will vary for different organisms and spores. Use only
fresh household bleach, dilute 1:10 with water immediately prior to disinfection, and
immerse materials for at least 6 hours (overnight is best). For increased safety using
bleach disinfection, open plates while they are under solution, not in air.
Autoclaving with steam and dry heat sterilization are the preferred methods for
achieving sterilization. The following materials should never be placed in an
autoclave: flammable, combustible or volatile liquids and any liquid in a sealed
container. Check with local authorities to determine whether autoclaved bags may
be disposed of as general waste.
• Objects to be autoclaved (e.g., Petri dishes, culture tubes) should be placed into
the autoclave or biohazard bags without opening the containers.
• Loosely close but do not seal the bags—steam must penetrate the materials for
effective sterilization—and place then on trays inside the autoclave to capture
potential spills.
• Depending on the load density, typical sterilization conditions are 30 minutes
at 121 °C and 15 psi pressure. The requirements for length of autoclaving and
temperature increase at higher altitudes.
• Carefully follow the manufacturer’s instructions and all safety precautions,
including the use of PPE.
• The use of a biological or chemical indicator, such as autoclave indicator tape, is
highly recommended. Some state authorities may require periodic validation of
autoclave operation using bacterial strips or cultures.
• Do not place sharp objects into an autoclave bag.
Sharp objects, such as needles, razor blades and glass pipets, must be collected
in a labeled, puncture-proof container. Sharps that are contaminated with
potentially hazardous biological materials or fluids should be sterilized prior to
collection and/or disposal.
Type II Potentially Harmful Wastes Due
to Dangerous Chemical Hazards
Examples
Solutions from electrophoresis or staining procedures, formaldehyde solutions or
other chemical solutions or solids.
HAZARDS
Chemical wastes may be corrosive, toxic or flammable and should be handled
accordingly. If the waste material is of unknown composition, assume the material
is toxic, corrosive and flammable and take all precautions when handling the
material. Contact Flinn Scientific for advice on how to identify and dispose of
unknown chemical wastes.
Disposal Procedure
If the identity of the chemical waste is known, then consult the chemical waste
disposal section of the Flinn Scientific Catalog/Reference Manual To find the
Ecological studies have repeatedly demonstrated the intertwined nature of all
elements of the ecosystem. A basic ecological principle simply states—“You can’t
do just one thing.” So when we dispose of materials we are likely to do more than
just dispose of the materials. When considering the disposal of any material, our
goal must be to minimize the environmental impact of the disposal (i.e., come
as close to doing “one thing” as possible). Common sense, a knowledge of the
material and a familiarity with local disposal regulations, procedures and policies
must prevail. The general guidelines provided here are only intended to stimulate
clear thinking about how to minimize our effects on the environment as we recycle
Earth’s materials.
One important first step is to formulate a biological waste disposal policy. General
guidelines and parameters should be written prior to conducting actual disposal
procedures. Follwing are some suggestions that might help in formulating a general
biology disposal policy:
• Contact the facilities staff for information about ongoing disposal programs.
• If applicable, get in touch with your state science supervisor or department of
education. Many states have implemented clean-up campaigns in recent years.
The state EPA may also have an existing program.
• Work with the state and local associations. Use the experience of other
experienced instructors to help your school comply with disposal requirements.
• Seek the advice of your Environmental Health and Safety Department or that of a
nearby college or university. Most large universities have ongoing waste disposal
programs and understand state and local requirements.
• Contract with a licensed hazardous waste disposal firm for removing chemicals.
Because the institution has cradle-to-grave responsibility for its chemicals, even
after they have been removed from the site, it is vital that you choose a licensed
and reputable firm. Ask for and check references, and do not automatically
choose the lowest bid. Request a certificate of disposal for the chemicals.
When conducting any disposal procedures, be sure to provide personal
protection for yourself and others around you. Always wear proper personal
protection equipment (e.g., goggles, aprons, gloves). Conduct disposal procedures
in proper areas for the materials (e.g., hoods, ventilated areas, appropriate sinks).
Where appropriate, follow sterile procedures and cautions relative to potential
pathogens.
We have arbitrarily divided waste materials into six categories for the sake of
discussion and clarity. Some situations might involve a combination of several
of the categories. Specific federal, state and local regulations may apply to the
disposal of biohazards from your lab. You must review your obligations and options
with regulatory and school officials before developing a disposal procedure at your
school.
Type I: Potentially harmful due to microorganism-type contamination
Type II: Potentially harmful due to dangerous chemical hazards
Type III: Preserved materials
Type IV: Living materials
Type V: Sharps and glass items
Type VI: Common garbage items
Type I Potentially Harmful Wastes
Due to Microorganism-Type
Contamination
Biology, microbiology and biochemistry labs may generate wastes that must be
managed as potentially infectious, biohazardous or regulated medical waste.
Disposal of biohazardous wastes is subject to regulation by numerous authorities,
including federal or state OSHA (for bloodborne pathogens), state environmental
protection agencies and local wastewater treatment plants. Review the following
general guidelines and essential equipment needed for the sterilization and
ultimate disposal of biological wastes before planning laboratory activities involving
the use of microorganisms, body fluids or recombinant DNA. Check with your state
and local agencies for specific regulations regarding biohazardous waste disposal.
Examples
• Microbiological cultures and stocks, including all bacterial cultures and
culture tubes
BIOLOGICAL WASTE DISPOSAL—TYPE II continued on next page.