Page 261 - Demo

“Your Safer Source for Science”
Biological Waste Disposal
259
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 materi- als 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 envi- ronment 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. 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 depart- ment of education. Many states have implemented cleanup 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 instructors who have faced similar issues 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 (goggles, aprons, gloves, etc.). Conduct disposal procedures in proper areas for the materials (hoods, ventilated areas, appropriate sinks, etc.). 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.
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
• 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 environ- ment should NOT be incubated at temperatures higher than 25 oC 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 house- hold 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 solu- tion, 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 is autoclaved bags may be disposed of as general waste.
• Objects to be autoclaved should be placed into the autoclave or biohazard bags without opening the containers (Petri dishes, culture tubes, etc.).
• Loosely close but do not seal the bags—steam must penetrate the materials for effective sterilization—and place the bags on trays inside the autoclave to capture potential spills.
• Depending on the load density, typical sterilization conditions are 30 minutes at 121 oC 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.
BIOLOGICAL WASTE DISPOSAL continued on next page.
Type I:
Type II: Type III: Type IV: Type V: Type VI:
Potentially harmful due to microorganism-type contamination
Potentially harmful due to dangerous chemical hazards Preserved materials
Living materials
Sharps and glass items
Common garbage items
Biological Waste Disposal
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 regula- tion by numerous authorities, including federal or state OSHA (for bloodborne pathogens), state environmental protection agencies, and local wastewater treatment plants. Review the following general guide- lines 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