Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
RADIOACTIVE AND NUCLEAR MEDICINE WASTE MANAGEMENT IN A HOSPITAL
UMAR MU’AZU TADAMA1, PHARM DAUDA ABDUL-MARUFF2, AARON KUSHUAI BAKUT3 OJO SAMUEL4 1, 3 &4
Department of Chemical Engineering Technology, Federal Polytechnic Mubi 2School Clinic, Federal Polytechnic Mubi
ABSTRACT The application of radioactive materials in medical diagnosis and therapy is extremely important and continuously growing. By using radioactive tracer elements, physicians can learn of the presence of disease. Radiation therapy is useful in controlling the spread of many types of cancer. Both types of activities result in the production of low-level radioactive waste. A very wide spectrum of radionuclides is available for hospital usage such as Tritium -3, Carbon-14, Cobalt-57, and other sources, which are generally classified as low level short lived radioactive waste. Safe disposal of the radioactive waste is a vital component of the overall management of the hospital waste. An important objective in radioactive waste management is to ensure that the radiation exposure to an individual (Public, Radiation worker, Patient) and the environment does not exceed the prescribed safe limits. Disposal of Radioactive waste in public domain is undertaken in accordance with the Atomic Energy (Safe disposal of radioactive waste) rules. Any prospective plan of a hospital that intends using radioisotopes for diagnostic and therapeutic procedures needs to have sufficient infrastructural and manpower resources to keep its ambient radiation levels within specified safe limits. Regular monitoring of hospital area and radiation workers is mandatory to assess the quality of radiation safety. Records should be maintained to identify the quality and quantity of radioactive waste generated and the mode of its disposal. Radiation Safety officer plays a key role in the waste disposal operations. The current status and future plan for the medical radioactive waste generation and their impact on the hospital environment is described, as well as the impact of medical radioactive waste on the broader aspects of radioactive waste management.
Keywords: Radioactive, Nuclear, Medicine, Hospital, Waste, Generation, Disposal, Safety, Regulation
INTRODUCTION Radioactive waste management in hospital gains a lot of momentum in the 21st century, due to the large usage of radioactive materials in different Applications. Most of the radioactive wastes that are produced in hospital are in the categories of low level wastes and small quantity considered as an intermediate level. All low-level radioactive waste, regardless of its source, must be carefully managed to minimize risk to people and the environment. The low level radioactive wastes are generated from mainly medical facilities, such a hospitals, which have grown to depend on the use of radioactive materials for diagnosing and treating patients. By using radioactive tracer elements, physicians can learn of the presence of disease. Radiation therapy is useful in controlling the spread of many types of cancer. Both types of activities result in the production of low -level radioactive waste. This can include contaminated syringes, linens, paper products, and waste liquids, as well as protective clothing worn by both hospital personnel and patients. The second source of low- level radioactive waste is Industrial process. Radioactive materials are used extensively to measure the thickness of materials (IAER, 1997; Umar, 2006).
Spectrum of Radionuclides Available for Hospital Usage Hospitals are increasingly using radioactive isotopes for diagnostic and therapeutic applications. The main radioisotopes used in hospitals are technetium-99m (Tc-99m), Iodine-131(I-131), Iodine-125 (I-125), Iodine-123(I-123), Flourine-18(F-18), Tritium (H-3) and Carbon-14(C-14), Cobalt-57.The bulk of the hospital radioactive waste gets generated in the department of Nuclear Medicine. There are more than 200 Nuclear Medicine centers in India alone, that include five independent Positron Emission Tomography (PET) centers, are currently performing approximately 1.25 million studies annually. Most of the radioactive waste is liquid, with lesser amount of solid and minimal gaseous. The solid waste containing traces of radioactivity is in the form of syringes, needles, cotton swabs, vials, contaminated gloves and absorbent materials. Clothing and utensils of patients administered high doses of radioisotopes like I-131 constitute the solid radioactive waste material. Safe disposal of unused radioactive material and objects contaminated with it is a vital component of the overall strategy of hospital waste management. The fundamental objective of safe disposal of radioactive waste is to ensure that the radiation exposure to public, radiation workers and environment does not exceed the prescribed safe limits (ICRP, 1995; Murthy, 2000). Keeping the exposure levels within the prescribed limits reduces the short term and long-term effects of ionizing radiations on humans, besides reducing its negative impact on environment. Any prospective plan for a hospital or clinical facility that envisages the use of radioactive isotopes needs to ensure structural and
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
functional parameters to keep the environmental radiation levels and personal radiation exposure of workers and public within the permissible limits (Tabish, 2005; Umar, 2006).
Basic Principles of Radiation Protection In addition to the management of radioactive hospital waste on scientific lines, the basic principles for radiation protection to be adopted are: •
Justification of practice (use radiation only if benefits outweigh the risks),
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Optimization of practice (keep magnitude of individual dose and number of people exposed to as low as reasonably achievable,) and dose limitation (Govida, 2002).
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Regular personal monitoring of hospital radiation workers, area monitoring of hospital environment and quality control of the radiation instruments is mandatory to assess the quality of existing radiation safety standards. (NCRP, 1089)
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Every hospital should have a designated Radiation Safety Officer (RSO) who oversees all aspects of radiation safety including radioactive waste management.
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The RSO co-ordinates such measures in accordance with guidelines prescribed by the International Commission on Radiation Protection and the national regulatory body (RPR, 1971; Cherry, 1980). There are strong economic and social reasons for aggressively protecting the environment by managing the biomedical waste scientifically, so essential for sustainable development (Tabish, 2005).
Table 1: Usage of different isotopes in different medical applications
(Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3068798/)
Basic Concepts in Radioactive Waste Management A unit is necessary for measurement of any physical quantity. The International Commission on Radiation Units and Measurement (ICRU) reviews and updates, from time to time, the concepts related to quantities and their units in radiation physics that are important for radioactive waste management (ICRU, 1980).
Activity (Quantity) of Radioactive Material Old unit (REM): Curie (Ci), millicuries (mCi) etc. Standard international unit (SI): Sievert (Sv), milliSievert (mSv) etc. Becquerel (Bq): Relative biological effectiveness (Equivalent dose / Effective dose) Exposure to different types of radiations (Gamma rays, X-rays, Alpha rays, Beta rays, Neutrons etc) differ in the extent of causing biological damage due to differences in their tissue damaging (ionization) properties. A unit exposure of gamma rays or X-rays will be less biologically damaging than unit exposure of alpha rays. Based on the biological damage caused, the following units are used.
Half-Life of a Radioisotope This is defined as the time interval for a particular radioactive material to reduce (decay) its radioactivity by half. For example, if there are 10 millicuries (mCi) of a commonly used diagnostic radioisotope Tc-99m at 2 pm, since its half-life is 6 hours, the remaining activity at 8 pm will be 5 mCi. Different isotopes have different half-lives. For practical considerations, a simple fact to remember is that the radioactivity remaining after 10 halflives of a radioisotope is about one-thousand of the original radioactivities (i.e., millicurie amounts are reduced to microcurie amounts). Half-lives of some commonly used radioisotopes are: Technetium-99m (Tc-99m) 6 hours. Iodine-131 (I-131) 8 days. Flourine-18 (F-18) 110 minutes. Cobalt-60 (Co-60) 5.271 years.
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
Tenth -Value Thickness (TVT) This is defined as the thickness of an absorber or shielding material that decreases the transmitted beam intensity by a factor of 10 or 0.1% of its original intensity. TVT of lead, the commonly used shielding material for some of the isotopes:
Table 2: The commonly used shielding material for some of the isotopes.
(Source: AERB, 1989).
Commonly Used Radioactivity / Radiation Measuring and Monitoring Devices Well counter: Scintillation based sensitive system for measuring radioactivity, mostly gamma rays. Dose calibrator: Ionization based chamber used for measuring radioactivity. Gun monitor: Ionization based portable survey meter used mostly for radiaton monitoring. Geiger Muller (GM) Counter: Ionization based sensitive system for detecting minutest levels of radiation contamination Film badge: Photographic film based personnel dose monitoring. TLD badge: Thermoluminescent dosimeter for personnel dose monitoring. Pocket Dosimeter: Ionization based personnel dose monitor that provides instant readout.
Classification of Radioactive Waste Radioactive waste can be classified in following ways. According to level of activity: •
High level waste
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
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Medium level waste
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Low level waste
According to the form:
Solid waste
Liquid waste
Gaseous Waste
According to half- life: Long half-life waste (Half-life more than a month) Short half-life waste (Half-life less than a month)
The hospital radioactive waste is mostly composed of low level waste and occasional medium level waste with short half-lives. The high level waste is usually associated with nuclear industry and nuclear reactors.
Disposal of Radioactive Waste Radioactive and nuclear medicine wastes composed of radionuclides that are: Low, Medium, and High-level waste that are segregated into several classifications: •
High-level waste produced in nuclear reactors, Consists of Fission products (shorthalf-lives), Actinides (long-half-lives). High level waste consists of fissionable elements from reactor cores and transuranic wastes; transuranic waste is any waste with transuranic alpha emitting radionuclides that have half-lives longer than 20 years. High level waste has a large amount of radioactive activity and is thermally hot.
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Low level waste is not dangerous but sometimes requires shielding during handling, Contains very low concentration of radioactivity, Waste which does not require shielding during normal handling and transportation. Low level nuclear waste usually includes material used to handle the highly radioactive parts of nuclear reactors.
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Intermediate level waste typically is chemical sludge and other products from reactors, Waste which requires shielding but needs little or no provision for heat
dissipation during its handling and transportation typically is chemical sludge, resins, metal fuel cladding and other products from reactors (Umar, 2006).
The radioactive waste at hospitals/nuclear medical centers mainly comprises of low level Solid Liquid and Gaseous waste
Solid Waste: Solid waste mainly consists of used Molybdenum-Technetium generators, empty vessels, swabs, syringes, gloves, laboratory clothing, bench covers, absorbents etc. Liquid Waste: Liquid waste includes washing from active labs, and excreta of patients injected. Biological waste such as excreta is regarded as liquid waste. Gaseous Waste: Gaseous waste generally includes working with, tritium and tritiated water, iodine and xenon-133.
Radioactive Waste Pretreatment and Retrieval Pretreatment is the initial step that occurs just after generation. It consists of collection, segregation, chemical adjustment and decontamination. Treatment involves changing the characteristics of the waste. Basic treatment concepts are volume reduction, radionuclide removal and change of composition. Conditioning involves those operations that transform radioactive waste into a form suitable for handling, transportation, storage and disposal. Storage facilities may be co-located with a nuclear power plant or a licensed disposal facility. The intention of storage is to isolate the radioactive waste from environment. Retrieval involves the recovery of waste packages from storage either for inspection purposes, for subsequent disposal or further storage in new facilities. Disposal consists of the authorized emplacement of packages of radioactive waste in a disposal facility.
Disposal Facility for Low Level Radioactive Waste (LLW). Near surface disposal: disposal in a facility consisting of engineered channels or vaults
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
constructed on the ground surface or up to a few tens of meters below ground level. Hanford (Nuclear News, November 2004) Disposal of intermediate level waste: Depending on its characteristics, intermediate level radioactive waste (ILW) can be disposed of in facilities of different types. Disposal could be by emplacement in a facility constructed in caves, vaults or silos at least a few tens of meters below ground level and up to a few hundred meters below ground level. Geological disposal: disposal in a facility constructed in tunnels, vaults or silos in a particular geological formation at least a few hundred meters below ground level. Such a facility could be designed to accept high level radioactive waste (HLW), including spent fuel if it is to be treated as waste. •
First used in 1999 in the US.
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Similar concept to basic geological repositories
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Kilometers deep rather than hundreds of meters
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Provide further isolation from ground water
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More potential borehole locations around the globe
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Can be created in many cases close to power plants
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Near infinite storage space
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Completely removes waste from biosphere
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Technical risks and problems
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High risk of space vehicle failure
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Relatively limited volume per launch High energy cost of space launch the current cost to launch an object into orbit around the earth is about $20,000 per kilogram.
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Beamed energy technology (BEP) HLW is most dangerous byproduct of nuclear power.
Optimizations of ion exchange Results in compact form of waste that will not interact with biosphere Research of Deep Boreholes Further development of deep boreholes that are more reliable are ideal option Reasonable Cost Global availability Human Safety (Muhammad, 2013)
Radioactive Waste Treatment and Disposal Disposal is the emplacement of waste in an approved specified facility (for example, near surface or geological repository) without the intention of retrieval. Disposal may also include the approved direct discharge of effluents (for example, liquid and gaseous wastes) into the environment with subsequent dispersion. There are two main approaches to the disposal of radioactive waste. One is characterized as "dilute and disperse" and the other as "confine and contain". By the "dilute and disperse" concept, radioactive material, in aqueous or gaseous form, is released into the environment in such a way that the material is diluted and distributed over a large volume so that the final concentration of radionuclides is acceptably low. In the "confine and contain" approach, the waste is collected and converted into a form such that, when placed in a repository, it will retain the radionuclides until the activity has decayed, or at least will ensure that the leakage of radionuclides from the repository does not give rise to unacceptable concentrations anywhere in the environment. This approach is always used for longer-lived solid radioactive waste. During transportation, safety management includes appropriate packaging, labeling, and transportation of documents including sender, retriever, and content of the waste, categorization, and information to possible rescue personnel. The packages and containers should always be strong enough to ensure a safe, sometimes rough, handling. The transportation should follow the IAEA guidelines. (IAEA 1986). The collected radioactive waste is disposed as per the following: •
Dilute and Disperse
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Delay and Decay
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Concentrate & Contain (Rarely used)
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Incineration (Rarely used)
Dilute and Disperse: Low activity solid article may be disposed off as ordinary hospital waste provided the activity of the article does not exceed 1.35 microcuries (50 KBq) or the overall package concentration does not exceed 135 microcuries / m3 (5MBq / m3). Such articles include vials, syringes, cotton swabs, tissue papers etc. Similarly, liquid radioactive waste with activity less than microcurie level can be disposed off into the sanitary sewerage system with adequate flushing with water following the disposal. However, the maximum limit of total discharge of liquid radioactive material into sanitary sewerage system should not exceed the prescribed limits (ICRP, 1995).
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
Disposal limits for Sanitary Sewerage System
Delay and Decay: Medium activity radioactive waste and those with half-lives of less than a month may be stored. The storage room should be properly ventilated with an exhaust system conducted through a duct line to a roof top exit. The storage space should have lead shielding of appropriate thickness (10 HVL) to prevent radiation leakage. The radioactive waste should be stored for a minimum period of about 10 half-lives when after decay only 0.1% of the initial activity remains. The waste is then monitored for the residual activity and if the dose limit is low it is disposed off as low activity solid or liquid waste. Most of the low and medium level radioactive hospital waste is of short half-life permitting this type of waste disposal (Al Marshad et al., 1997).
Concentrate and Contain: This technique of radioactive waste disposal is sometimes used for radioactive materials with very high activity levels and for those with long half-lives (longer than a month). Their disposal by delay and decay method is impractical because of longer storage period, particularly if space availability is limited. Radioactive waste is collected in suitably designed and labeled containers and then buried in exclusive burial sites approved by the competent authority. In day-to-day work of a hospital, we do not come across radioactive waste of this nature and as such, this method of radioactive waste disposal is rarely used (ICRP, 1995).
Incineration: Insoluble liquid waste such as that from the liquid scintillation systems may be disposed off by incineration. Incineration reduces the bulk of waste and the activity is concentrated in a smaller volume of ash for further disposal. Since incinerators used for radioactive waste disposal release part of the radioactivity into the atmosphere they should operate under controlled conditions and in segregated places. Ashes collected have to be disposed off as solid radioactive waste separately. Environmental concerns and public pressure severely restrict the methods of ground burial and incineration as regular options of radioactive waste disposal. For these reasons, incineration and burial are rarely recommended (Umar, 2006).
Special situations of Radioactive Waste Management in a Hospital Disposal of sealed sources: Hospitals use sealed sources for a variety of applications, including teletherapy, brachytherapy, blood irradiation, calibration etc. Most of these sources are relatively small with activities ranging from a few up to a few hundred MBq, except the teletherapy and blood irradiation source, which may have high activities. Once the source becomes weak for further applications it has to be removed and replaced. Hospitals ordering and using such equipment must enter into a contract for safe removal and replacement of the sealed radioactive source with the suppliers. While ordering such equipment and the source, the Radiation Safety Officer of the hospital should be taken into confidence.
Tale 3: Disposal limits for radioactive waste according to IAER Law
(Source: Al-Owain & Al-Marshad, 1997) Disposal of gaseous waste: Volatile radioactive sources like Iodine-131 and Iodine-125 release radioactive vapors, generating airborne radioactive waste. The containers of such radioactive substances should be opened under fume hoods connected through duct lines to highest roof top exit. Before the vapors are diluted and dispersed into the atmosphere, they should pass through charcoal and particulate air filters. Hospitals using radioactive gases should have efficient laminar airflow system. Other gaseous radioactive waste generating isotopes used are Xenon-133, Carbon-14, Hydrogen-3, Nitrogen-13, Technetium-99m aerosols (Al Marshad,
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
1997).
Disposal of Excreta and Urine of Patients Administered High Doses of Radioisotopes: Patients administered high therapeutic doses of radioisotopes (e.g., Iodine-131 in thyroid cancer) are admitted in isolation wards until their radiation emission levels are within the minimum safe limits (3 m Roentgens per / Hour at 1meter distance). The excreta and urine of patients admitted in a high dose isolation ward (e.g. Iodine −131) after getting flushed passes the PVC pipes through the shortest route possible into customized storage tanks, called delay tanks for storage before dispersal into the sewerage system. The delay tank should be located in an area where there is minimal movement of public (Kinni, 1998). The tank should be leak proof, corrosion free and should have smooth surface from inside. The capacity of the tank depends on the number of patients admitted each day. A facility admitting two patients would require two delay tanks of 6000 liters each. This capacity is based on the presumption that on an average each patient uses about 100 liters of water per day. At that rate, each patient will use 3000 liters per month and two patients will use 6000 liters. At the end of one month as the tank will be full, it is closed and the gate valve of the second tank is opened. The full tank is kept closed for the period of one month that the second tank takes to fill. As such, each tank holds the radioactive waste for 2 months that is sufficient for the decay of Iodine-131 to low levels (Delay & Decay). However before releasing the effluent of the tank into the public sewerage system a sample is collected to check the activity, this should not be more than 1.2 microcuries per liter. No hospital is permitted to release into public sewerage system an aggregate 37 G Bq (1 Curie) of liquid radioactive waste in one year (Nagalakmi, 2000).
Management of cadavers containing radioactive material: Sometimes a situation may arise when a patient suffering from a disease such as thyroid cancer is administered a high dose of iodine-131 and the patient dies while she or he is in the hospital and still has very high levels of radioactivity in her or his body. In such a situation, one has to inform the Radiation Safety Officers who in collaboration with the Nuclear Physician supervise the future course of action. If high activity is concentrated in an organ like residual thyroid, than the same may need to be removed (Autopsy). If the activity is in a metastatic site, an effort to remove that site may also be undertaken. Once it is established that the cadaver has radioactivity less than the safe limit recommended by
the competent authority, the dead body may be handed over for disposal through burial or cremation without any special precautions (Nagalakmi, 2000) In case, the levels of radioactivity are high than the corpse is retained in the hospital mortuary until the activity decays to safe limits.
Advisory / Regulatory bodies and Record keeping The usage of radioisotopes and disposal of radioactive waste is done in accordance to recommendations and guidelines issued by various international and national bodies. Institutional Head, Departmental Head, and Radiation Safety Officer of the institution have to co-ordinate their activities with the national regulatory body. Authorization for procurement, usage and disposal of radioactive waste from the regulatory body is mandatory. The following bodies play key roles in ensuring safe use of radioisotopes and safe disposal of the radioactive waste: •
International Commission on Radiological Protection (ICRP): This body was founded in 1928, under the then name of “International X-ray and Radium Protection Committee.” ICRP is an international advisory body providing recommendations and guidance on radiation protection (http://www.icrp.org/). The secretariat of this body is located in Sweden (http://www.icrp.org/).
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Atomic Energy Regulatory Board (AERB): This national apex regulatory body was constituted in 1983 to perform certain regulatory and safety functions. The main mission of AERB is to ensure that the use of ionizing radiations and nuclear energy does not cause undue risk to health and environment (http://www.aerb.gov.in/). The Atomic Energy Act of 1962 governs the use of radioactive materials and radiation generating equipment. The Chairman of the AERB is designated as the Competent Authority to enforce these rules. The employer, which may be the Head of the institution, shall obtain an authorization from the Competent Authority for disposal of radioactive waste either locally or through authorized waste disposal agency. The Chairman, AERB may issue Surveillance procedures, codes, standards, and guides which elaborate the provisions of Rules for implementation. The office of AERB is located in Mumbai (http://www.aerb.gov.in/).
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Radiation Safety Officer (RSO): The employer shall employ a RSO with the requisite minimum qualification approved by the competent authority (AERB, 1989). The RSO shall advise and assist the employer in safe disposal of radioactive waste in accordance to the guidelines issued from time to time by the competent authority. The RSO has the key role to ensure all aspects of radiation safety, including safe disposal of radioactive waste in the institution. However, the ultimate
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
responsibility for the same rests with the employer. •
Record Keeping: Proper records in the form of logbook must be maintained. Details of diagnostic and therapeutic radioisotopes procured and administered should be recorded. The records must also include the details of radioactive waste generated with the activity levels and the levels at the time of their disposal. The activity levels in the effluent of delay tank must be recorded prior to disposal into public sewerage system. The total activity disposed off annually in the sewerage system should be recorded (Umar, 2006).
Waste Management and Segregation in Nuclear Medicine The solid waste generated in nuclear medicine includes cover papers, gloves, empty vials and syringes, radionuclide generators, items used by hospitalized patients after radionuclide therapy, sealed sources used in therapy, sealed sources used for the calibration of instruments, animal carcasses and other biological waste. In the liquid waste category one can find residues of radionuclides, patient excreta, liquid scintillation solutions, and in the gaseous waste exhausted gas from patients in nuclear medicine. Depending on the final handling or disposal, the waste could be divided into different categories. One category where the waste will end up in a public waste treatment system with or without incineration, the next where it will be poured out in the public sewage system, and the third where it will be disposed of in a national plant or recycled. The segregation could be done in the following categories:
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Solid waste which after proper treatment and conditioning can be handled in the public waste treatment system. Solid waste should be immobilized by surrounding it with a matrix material in order to produce a waste form suitable for storage and transportation governed by the properties of the waste, the transport regulations and the specific waste treatment or disposal acceptance requirements. Incineration is recommended for combustible solid waste because it achieves the highest volume reduction and dilutes and disperses the radionuclide content. Total sterilization of biological waste will be achieved. Discharge limits given by the regulatory authority should be followed.( IAEA 1985)
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Liquid waste which after proper treatment and conditioning can be handled in the public waste treatment system. For aqueous waste evaporation, chemical precipitation and ion exchange may be considered. For organic and infectious liquid waste incineration is a suitable method. The residues of the treatment process
should be handled as solid waste. Treated aqueous effluents can be discharged in the environment via the sewage system if either clearance has been granted for the radioactive substance or the discharge is within the limits authorized by the regulatory authority (IAEA 1986). •
Solid waste containing short-lived radionuclides capable of being stored for decay. Thereafter it may be handled in the public waste system if the discharge is within the limits authorized by the regulatory authority
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Liquid waste containing short-lived radionuclides capable of being stored for decay. Thereafter it may be handled in the public waste system if the discharge is within the limits authorized by the regulatory authority.
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Sealed sources with high activities which will be disposed of in a national plant or recycled. Biological waste, which may undergo decomposition. A suitable treatment method is incineration. Infectious waste requiring sterilization possibly by incineration prior to disposal (IAEA 1988).
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Broken glass-ware, syringes etc, requiring collection in separate containers to prevent personnel being injured. Depending on other content, radionuclide type, biological, infectious etc. it should be appropriately handled, treated and stored.
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Radionuclide generators should after storage for decay be checked for contamination and dismounted or, preferably, returned to the producer.
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Bed linen and clothing from hospital wards, which are contaminated, could be stored for decay if the nuclides are short-lived. Otherwise it is treated as solid waste.
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Patient excreta. For diagnostic patients there is generally no need for collection of excreta. Ordinary toilets can be used. For therapy patients there are different policies in different countries. Either to use separate toilets equipped with delay tanks or an active treatment system, or allow the excreta to be released directly into the sewage system.
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Liquid scintillation solutions, which due to its flammable organic solution, could preferably be disposed of by incineration. New types of liquid scintillation solutions are less flammable and hazardous to the environment could otherwise be handled in the public waste treatment system.
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Containers to allow segregation of different types of radioactive waste should be available in areas where the waste is generated. The containers must be suitable for purpose (volume, shielding, leak proof, etc.) Each type of waste should be kept in
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
separate containers properly labeled to supply information about the radionuclide, physical form, activity and external dose rate. •
A room for interim storage of radioactive waste should be available. The room should be locked, properly marked and if necessary ventilated. Flammable waste should be placed apart. It is essential that all waste be properly packed in order to avoid leakage during the storage. Biological waste should be refrigerated or put in a freezer. Records should be kept where the origin of the waste can be identified (IAEA 1993; IAEA 1989).
MATERIAL AND METHODS Healthcare institutions generate enormous amount of waste which is considered as potentially hazardous in view of the inherent potential for dissemination of infection. Hospitals generate on an average, between 0.5 and two kilograms of waste per bed per day (Tabish, 2005). It is estimated that about 85% of the waste generated is non-hazardous, about ten percent is infectious and 5% non-infectious but hazardous. The rising trends of HBV and HIV infection has led to an increasing awareness about the risk associated with improper management of biomedical waste and the need to evolve and implement strategies for safe and sustainable methods of disposal of waste (Tabish, 2005).
Fig 1: Percentage of Radioisotope Applications in Industrial, Medical and Research in Saudi Arabia 1996 (Source: http://www.wmsym.org/archives/2001/21c/21c-29.pdf) In order to minimize the impact of radioactive wastes left after the various applications in these very expanding applications of radioisotopes in the modern life of the people, there should be a plan to control this growing use of the radioactive materials to prevent the hazard waste from effecting human health and the environment. Since it is not very difficult to manage the radioactive wastes deriving from medical use of radioisotopes. A stiff law and regulations should be Implemented on all kind of medical radioactive wastes. Hospital
should to adopt the following procedure to manage the radioactive wastes coming from all the medical facilities: Collection of the wastes from all departmental users. Segregate storage in different places for deposing for an appropriate number of half-
lives Disposal, by means of conventional system for waste treatment, when the amount of
radioactivity is below the limits, which are defined by national laws. While a national repository plan has been considered by IAER (Al-Owain & Al-Marshad, 1997), waste minimization may be applied at the source of waste generation (i.e. hospitals). The waste minimization idea can be initiated with the simple physical separation of noncompactablewaste (i.e. glass, metals) for compactable wastes (plastics, paper goods). This initial process is a highly desirable goal in a country that has no national repository facility.
DISCUSSION OF FINDINGS The management of radioactive waste involves two stages: collection and disposal. The radioactive waste should be identified and segregated within the area of work. Foot operated waste collection bins with disposable polythene lining should be used for collecting solid radioactive waste and polythene carboys for liquid waste. Collecting radioactive waste in glassware should be avoided. Each package is monitored and labeled for the activity level before deciding upon the mode of disposal. Some hospitals that have incinerators and permission to dispose of combustible radioactive waste through incineration may also segregate combustible radioactive waste from non-combustible waste. When two different isotopes of different half-lives like Tc-99m and I-131 are used, separate waste collection bags and bins should be used for each. Each bag or bin must bear a label with name of the isotope, level of activity and date of monitoring. Radioactive waste is generated from various applications such as medical, industrial, and research intuitions (Umar, 2006). These wastes are classified as low –level radioactive and small quantity consider as an intermediate level. The radioactive wastes, generated by these activities are divided physically into two groups; liquid wastes and solid wastes. Solid wastes divided into two groups, compactable solid wastes and non-compactable solid wastes. The non-compactable solid wastes such as spent sealed sources, metals, etc. compactable waste such as, clothes, gloves, etc. The application of radioactive materials in medical diagnosis and therapy is very important and expanding rapidly. In many cases alternative methods are not available. The main areas of application are diagnostic
Proceedings of the Academic Conference on Agenda for Sub-Sahara Africa Vol. 4 No. 2. 28th April, 2016 –University of Abuja, Teaching Hospital, Conference Hall, Gwagwalada, Abuja FCT-Nigeria
techniques, radiotherapy and research. These represent the use of not only small quantities of unsealed sources, but also highly concentrated sealed sources housed in shielded assemblies. These medical radioactive wastes generally classified as low level short lived sources. They represent more than 50% of radioisotope applications. Most industrial uses use particular forms of radioactive material such as sealed sources, luminous displays, and specialized electronic devices for not destructive testing, evaluation of plant performance and development of products. The quantities of radioactive materials used depend largely on the development and level of the national technology. As of now, one of the main sources of radioactive waste is the spent sealed radioactive sources which are imported to the study by different users under the supervision of Institute of Atomic Energy Research (IAER). These sealed sources consist of different types such as Cs-137, Sr90, and C0-60. Users of radioactive material in research centers and universities are commonly involved in monitoring the environmental pathways associated with materials as diverse as fertilizers, drugs, minerals, and pesticides. Co-60 has proved to be very valuable gamma rays emitters’ source. A very wide spectrum of radionuclides is available for research and study centers, they represents only 11% of the total radioisotope applications. The increasing use of unsealed radionuclides in medical applications for diagnostics and for therapy, presents the need for safe management of radioactive wastes in order not to pollute the environment. A study showed that hospitals and possibly other institutions are disposing off a considerable amount of radioactive iodine in the domestic sewage system (Al Marshad et al., 1997). I-125 and I-131 were the most frequently detected medical radionuclides.
CONCLUSION AND RECOMMENDATIONS 21st century hospitals are increasingly using radioisotopes for diagnostic and therapeutic applications hence an emerging situation in medical waste management is arising from radiation Sources used in medicine and other fields. Medical scanning using a variety of radioactive positron emitters is emerging as a vital diagnostic tool in cardiology and oncology. All of this will lead to an increase in the amount of radioactive hospital waste. When these sources are no longer useable, they must be disposal of safely. However, many of the “disused” sources have not been or “might not” properly managed, sometimes remaining “problems” from competent authority and their control serious incidents have occurred in some other countries where mismanaged sources caused unwanted situations before being recovered or controlled. This waste will have to be disposed off in accordance to the guidelines provided by the International Atomic Energy Agency (IAEA) and regulated by national agencies like Atomic Energy Regulatory Board (AERB). An institutional coordinated effort within the National legal framework will ensure that the radiation
exposure to humans and environment remains within the permissible limits. Safe disposal of the radioactive waste is a vital component of this effort. This study would assist hospitals and all users in improving their capabilities for ensuring the safe control and disposal of radioactive wastes. The safe management of radioactive waste should rely on an advance laws and regulations that can be dealt with all the times. The government should have the responsibility to Treat, condition, transport and to store all wastes been generated by the produces in the safest manner. With the knowledge and information contain in this study, we can effectively and safely manage Hospital’s radioactive, nuclear and biomedical waste. By knowing the type of waste and the kind of radiation it emits, we can: •
Package the waste in materials that reduce the radiation, so that it is safe to handle and transport;
•
Safely store it in facilities that use effective shielding; and
•
Dispose of it in the ground using natural rock and soil, and install barriers like concrete to ensure the radioactivity does not enter the environment. This will prevent radiation from harming humans, animals or plants.
•
ensure that the activity and volume of any radioactive waste that results from the sources for which they are responsible be kept to the minimum practicable, and that the waste be managed, i.e. collected, handled, treated, conditioned, transported, stored and disposed of, in accordance with the requirements of the Standards and any other applicable standard
•
segregate, and treat separately if appropriate, different types of radioactive waste where warranted by differences in factors such as radionuclide content, half-life, concentration, volume and physical and chemical properties, taking into account the available options for waste disposal (IAEA, 1996).
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