Medical waste
Medical Waste are waste generated by health care activities such as hospitals, clinics, physician's offices, dental practices, blood banks, and veterinary hospitals/clinics, as well as medical research facilities and laboratories which includes a broad range of materials, from used needles and syringes to soiled dressings, body parts, diagnostic samples, blood, chemicals, pharmaceuticals, medical devices and radioactive materials.
Poor management of health care waste potentially exposes health care workers, waste handlers, patients and the community at large to infection, toxic effects and injuries, and risks polluting the environment.
Medical wastes includes the following:
- blood-soaked bandages
- culture dishes and other glassware
- discarded surgical gloves
- discarded surgical instruments
- discarded needles used to give shots or draw blood (e.g., medical sharps)
- cultures, stocks, swabs used to inoculate cultures
- removed body organs
- discarded lancets
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[edit] Types of Medical Waste
Medical waste can be identified by one of four different categories: infectious, hazardous, radioactive, and general.
[edit] Infectious
Infectious waste describes waste that has the possibility of causing infections to humans. It can include human or animal tissue (blood or other body parts), blood soaked bandages, discarded surgical gloves, cultures, stocks, or swabs to inoculate cultures. Much of this category, including human or animal tissue, can also be labeled as pathological waste, which can only be treated using specific methods. Pathological waste is either proven to contain pathogens, or could be perceived as containing pathogens.
[edit] Hazardous
Hazardous waste describes waste that has the possibility to affect humans in non-infectious ways. This type of waste includes sharps, which are generally defined as objects that can puncture or lacerate the skin, but can include needles and syringes, discarded surgical instruments such as scalpels and lancets, culture dishes and other glassware. Hazardous waste can also include chemicals, both medical and industrial. Some hazardous waste can also be considered infectious waste, depending on its usage and exposure to human or animal tissue prior to discard.
[edit] Radioactive
Radioactive waste describes waste resulting from nuclear medicine treatments, Cancer therapies and medical equipment that uses radioactive isotopes. Pathological waste that is contaminated with radioactive material is treated as radioactive waste rather than infectious waste.
[edit] General waste
General waste makes up at least 85% of all waste generated at medical facilities, and is no different from general household or office waste, and includes paper, plastic, liquids and any other materials that do not fit into the previous three categories.
[edit] Collection of Medical Waste
Medical waste must be collected and stored prior to treatment in a way that eliminates the possibility of interaction with humans, animals, or the environment. The method of collection and storage depends on the specific type of waste. However, medical waste containers are generally red, contain the word “biohazard” and are imprinted with the universal three-sided biohazard symbol. This standardization immediately identifies these containers as medical waste. General storage guidelinesinclude the following:
- Contaminated reusable sharps must be placed in containers that are puncture resistant, closeable, puncture resistant, leakproof on sides and bottoms, and labeled or color coded,
- Reusable sharps that are contaminated with blood or other potentially infectious materials must not be stored or processed in a manner that requires employees to reach by hand into the containers,
- Specimens of blood or other potentially infectious material are required to be placed in a container that is labeled and color coded and closed prior to being stored, transported or shipped,
- Regulated wastes (liquid or semi-liquid) must be placed in containers that are constructed to contain all contents and prevent leakage of fluids, labeled or color coded, and closed prior to removal,
- All bins, pails, cans, and similar receptacles intended for reuse are required to be inspected and decontaminated on a regularly scheduled basis.
- Labels must include the biohazard symbol, be fluorescent orange or orange-red or predominantly so, with lettering and symbols in contrasting color, and affixed as closely as possible to the container by adhesive or wire to prevent loss or removal.
[edit] Sharp Containers
Sharps containers are found in every medical office, and often in public places, for medical personnel and the general public to safely dispose of hypodermic needles. These containers are designed so the user is never exposed to any of the sharps already in the container, eliminating the possibility of contact or puncture by any of the used needles. Sharps containers are generally made of thick plastic, and have a door that opens and the user can insert the sharp into the container. When the door is closed, the sharp is dropped down into the main chamber of the container. The container functions much like a standard post office mailbox, in that the user cannot reach the sharps inside the container via the door. Sharps containers are also used for other categories of sharps, including scalpels and lancets.
Sharps containers are found in public locations, and can also be used by private individuals who use sharps in the home, such as diabetics who require regular injections of insulin. For home users, a sharps container is provided by a private disposal company. When the individual fills the container, the container is then mailed to the private disposal company for disinfection and destruction prior to disposal.
Other forms of medical waste containers include 55-gallon drums for larger volumes of waste, and thick plastic bags that will resist puncture. State regulations generally dictate the maximum amount of time that medical waste can be stored prior to treatment. For example, in the state of New York, storage of regulated medical waste is limited to seven days unless prior written approval has been granted. Medical waste must be stored separately from standard waste, without possibility of the two waste types mixing. All reusable storage containers must be disinfected after they have been emptied, unless they employ a disposable liner of some sort that is removed with the waste.
[edit] Medical Waste Treatment
The primary methods of treatment and disposal of medical waste are:
- Incineration
- Autoclaves
- Mechanical/Chemical Disinfection
- Microwave
- Irradiation
For all of these treatment types, the treated waste can generally be disposed with general waste in a landfill, or in some cases discharged into the sewer system. In the past, treatment of medical waste was primarily performed on-site at hospitals in dedicated medical waste facilities. Over time, the expense and regulation of these facilities have prompted organizations to hire private companies to collect, treat, and dispose of medical waste, and the percentage of medical organizations who perform their own treatment and disposal is expected to drop.
To ensure that each treatment method provides the proper environment for the destruction of biologicals, test packages containing a microbiological spore test indicator are regularly used to test the effectiveness of the treatment methods. Microbiological spores are the most difficult of biologicals to destroy, so when the test package cannot be cultured after treatment, the waste is considered properly treated. In treatment methods where shredding or maceration is employed, the test package is inserted into the system after the shredding process to avoid physical destruction of the test package. The test package is then retrieved from the waste after treatment.
[edit] Incineration
About ninety percent of medical waste is being incinerated. Incineration is the controlled burning of the medical waste in a dedicated medical waste incinerator. The waste generally passes through the incinerator on a belt, and because most medical waste can be incinerated, the waste is not sorted or separated prior to treatment. Incineration has the benefit of reducing the volume of the waste, sterilizing the waste, and eliminating the need for pre-processing the waste before treatment. The resulting incinerated waste can be disposed of in traditional methods, such as brought to a landfill. The downside of incineration is potential pollution from emissions generated during incineration. The EPA has stringent requirements on emissions from medical incinerators. The incineration process can be applied to almost all medical waste types, including pathological waste, and the process reduces the volume of the waste by up to 90%.
Modern incinerators can provide a secondary benefit by harnessing the heat created by the incineration process to power boilers in the facility. The flames in the primary chamber can ignite fossil fuels in a secondary chamber and power facility boilers.
The largest concern associated with incineration is pollution. At least 20% of medical waste is plastic. The biggest concern is the incineration of chemicals that are released from combusting plastics. While incineration provides the advantage of reducing the volume of waste into ash and the ability to dispose recognizable waste and sharps, the incinerator may contain toxic gasses. Dioxins and furans can be produced when these plastics burn. The majority of older medical waste incinerators contain no pollution control equipment. As new federal and state emission regulations are instituted that have more stringent requirements, medical incinerators are often not being replaced at the end of their service life. Over time, the amount of waste being incinerated will be reduced as other technologies replace on-site incinerators. Another concern is related to the contents of incinerator ash. As incinerators are designed or retrofit with pollution prevention equipment, more of the potentially toxic chemicals that previously ended up in emissions now remain in the ash. Incinerator ash is generally disposed of in landfills, and little data is available on the effects of ash on the environment.
[edit] Health Effects
When wastes are incinerated at low temperatures or when plastics that contain polyvinyl chloride (PVC) are incinerated, dioxins and furans and other toxic air pollutants may be produced as emissions and/or in bottom or fly ash (ash that is carried by air and exhaust gases up the incinerator stack). Exposure to dioxins, furans and co-planar PCBs may lead to adverse health effects.
Long-term, low-level exposure of humans to dioxins and furans may lead to the impairment of the immune system, the impairment of the development of the nervous system, the endocrine system and the reproductive functions. Short-term, high-level exposure may result in skin lesions and altered liver function. Exposure of animals to dioxins has resulted in several types of cancer.
[edit] Autoclaves
Autoclaves are closed chambers that apply both heat and pressure, and sometimes steam, over a period of time to sterilize medical equipment. Autoclaves have been used for nearly a century to sterilize medical instruments for re-use. Autoclaves are used to destroy all microorganisms that may be present in medical waste before disposal in a traditional landfill. The autoclave lowers the pressure within the chamber, which shortens the amount of time required to generate steam.
Medical waste that is subjected to an autoclave is often also subjected to a compaction process, such as shredding, after treatment so that it is no longer recognizable and cannot be re-used for other purposes. The compaction process reduces the volume of the treated waste significantly. After treatment and compaction, the treated waste can be combined with general waste and disposed of in traditional manners. Waste that is treated using an autoclave is still recognizable after treatment, and therefore must be shredded after treatment to allow for disposal with general waste. Autoclaves are not recommended for the treatment of pathological waste, due to the recognizability factor after treatment, and that pathological waste may contain low levels of radioactive material or cytotoxic compounds. The autoclave process can aerosolize chemicals present in the waste and depending on the design of the autoclave, these chemicals can be released into the air when the autoclave is opened.
Autoclaves can be used to process up to 90% of medical waste, and are easily scaled to meet the needs of any medical organization. Small counter-top autoclaves are often used for sterilizing reusable medical instruments. Large autoclaves are used to treat large volumes of medical waste at once.
Steam sterilization provides generators a way to treat waste in a cost-efficient manner. The destruction of the microorganisms is highly effective, but the problem comes when transportation is required. Many landfills and general incineration facilities are reluctant to accept the waste, fearing the waste is infectious.
Recent work in Japan has found a method of chemicaly stabilizing heavy metals in fly ash from medical waste incinerators. Much development goes on in Japan, including recent work on a dual torch plasme arc furnace.
