MEDICAL & LABORATORY WASTE MANAGEMENT

Dr. Samwel V. ManyeleMedical Waste Management Research

Department of Chemical and Process Engineering, University of Dar es Salaam

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REASONS FOR POOR IPC• Inadequate knowledge and skills

among healthcare workers• Lack of guidelines and standards for

certain procedures• Deficiency of equipment and material• Inadequate supportive supervision• Lack of renovation and maintenance of

the infrastructure

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WHY PROMOTE IPC?• Increased risk from blood born infection like

HIV, HBV, and HCV• HIV/AIDS has increased the risk for

transmission (every person is regarded as infected)

• Raised awareness of how risky it is to work in healthcare facilities

• Advancement in healthcare provisions –scientific information, new technologies in providing safe and effective preventive services

• These services are provided in congested settings

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Introduction• Different medical activities generate

waste. • Some of which are hazardous and

can cause detrimental effects to human health and the environment if mismanaged.

• Generators must manage hazardous/infectious waste safely from "cradle to grave," that is, from generation, storage, treatment, and transportation, to ultimate disposal.

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DEFINITION1)Solid waste (mixed type)2)Generated during the diagnosis,

treatment, or immunization of human beings or animals

3)During research research 4)During production or testing of

biologicals 5) Liquids, semisolids, or contained

gases

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Waste Generated is Infectious

• Based on induction of disease to practitioners

• Presence of pathogens of sufficient–Virulence, Dose

• Worker exposure via –Portal of entry and

compromised resistance of host

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What properties make medical & lab waste hazardous?

• Toxicity –chronic, acute

• Carcinogenicity• Teratogenicity• Mutagenicity

• Can it explode?• Will it corrode or

burn skin?• Is it flammable?

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Prepare for Legal Compliance

• This is the key medical & lab waste management requirement.

• It is related to storage, hauling, treatment, and final disposal

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Elements of Infectious Waste Management

Identification of infectious wasteSegregationPackagingStorageTransport and handlingTreatment techniquesDisposal of treated wasteContingency planningStaff training

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Infectious Waste TreatmentChange bio-chemical character of waste

1. Monitoring of all treatment processes to assure efficient and effective treatment.

2. Use of biological indicators to monitor treatment

3. Waste types appropriate for treatment technology

4. Most types of medical/lab waste can be treated by incineration (changes volume and weight of waste but cannot remove radioactivity)

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Infectious Waste TreatmentFactors to consider while selecting treatment

method

Sterilization efficacyMaintenance & operator skillsAir emissionWater emissionsTreated waste characteristics

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Medical waste Incineration

•Volume & weight reduction•Effective destruction/sterilization•Can treat most types of wastes•Little processing prior to treatment•Renders waste unrecognizable•Best available technology for destroying organic solid wastes.•Medical waste = high BTU value.

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Other treatment methods

Do not destroy the waste but does destroy the pathogens.

Examples:• Steam autoclave• Microwave irradiation• Chemical Treatment• Radio frequency irradiation.

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Pathogens in the medical waste

Reduce risks by eliminating modes of transmission between humans and the pathogensExpose pathogens to temperatures encountered in incinerationExposure remains in survived fractions (ash, smoke) and escape during loading.Apply testing protocols

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Microbial inactivation•How do we know the medical or lab waste treatment system is working effectively?

•Through testing of survivability of microorganisms.

•A common mathematical model for thermal death rate of microorganisms is given by the following equation:

N = No x e-kt

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Inactivation levelsViable cells

at t = 0

Viable cells at time t

Reduction factor

Inactivation levels

Time to achieve

inactivation level

% reduction

106 105 10 1Log10

2Log10

106 102 10,000 4Log10 4D 99.99

6Log10

106 104 100

901D

2D 99

6D 99.9999106 100 =1 1,000,000

Where D = decimal reduction time = 2.303/k

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Microbial Inactivation• Spores are more resistant to heat that

vegetative cells.• Microbial inactivation must be designed

for viable spores.• Wet (steam) heat is faster in destroying

spores than dry heat at the same temperature.

• Spores may form more heat resistant aggregates than single spores.

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Acceptable levels of microbial inactivation

Level III:Vegetative bacteria, fungi, all lipophilic and hydrophilic viruses, parasites, mycobacteria at a 6log reduction or greater; and inactivation of B.stearothermophilus spores or B. subtilis spores at a 4log or greater

Level IV:vegetative bacteria, fungi, lipophilic/hydrophilic viruses, parasites, mycobacteria, and B.stearothermophilus spores or B. subtilis spores at a 6log or greater.

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Table 2. Recommended biological indicators

Vegetative Bacteria

Staphylococcus aureus (ATCC 6538)Pseudomonas aeruginosa (ATCC 15442)

Fungi Candida albicans (ATCC 18804) Penicillium chrysogenum (ATCC 24791)Aspergillus niger

Viruses Polio 2, Polio 3MS-2 Bacteriophage (ATCC 15597-B1)

Parasites Cryptosporidium spp. oocystsGiardia spp. Cysts

Mycobacteria Mycobacterium terraeMycobacterium phleiMvcobacterium bovis (BCG) (ATCC 35743)

Bacterial Spores Bacillus stearothermophilus (ATCC 7953)

Bacillus subtilis (ATCC 19659)

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Procedures for testing Medical Waste Incinerators

– Using microorganisms described for level III and IV.

– The microorganisms are charged into the equipment together with actual medical waste load by spraying (or in a ampule for incinerator).

– The end of a batch treatment, the microorganisms are retrieved under aseptic condition and tested for survivability.

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The microorganisms selected represent pathogen surrogates,

may be pathogenic under certain conditions.

Thus, all testing be conducted using recognized microbial techniques.

Efficacy testing should be conducted by qualified laboratory personnel only.

Precautions

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Handling Chemical CharacteristicsWhen hazardous chemicals are mixed with infectious waste, the hazardous component is given first priority.Prefer treatment options which can handle both hazardous chemicals and infectious waste together.Sometimes the infectious nature can be addressed first before hazardous treatment (to avoiding exposure during handling)

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The Chemical WastesVapors, spills, soaked materials Some are precursors of dioxins and furans, suspected carcinogens (Cl in the waste)Toxic metals (Pb, Cd, Cr, Hg) are present in medical/lab wastePlastics in the waste contributes most of the Pb & Cd (thermo-and photo-stabilizers)

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Low-level radioactive waste (LLW)

Sources: Radiopharmaceuticals; nuclear medicine, Radio- immunology procedures

Medical & research institutions produce < 5% of the total volume of LLW in USAIn Tanzania, 90% of these wastes come from medical & research institutions. Currently, there is no disposal sites for LLW in Tanzania (TRUE/FALSE?)

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(LLW)Usually, radioactive materials used in diagnosis have a very short half life (hours to days).Hospitals do not store LLW with isotopes of half-lives greater than 8 days given the storage problems.

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Conclusions• Review and approval of waste treatment

technologies is needed in Tanzania. Guidelines with strict review and approval policy is needed.

• Occupational health and safety is in jeopardy, due to mismanagement of these wastes.

• Knowledge dissemination is the key towards minimization of the problems.

• It is expensive to generate waste of any kind! So, minimize or don’t generate.

• Full cost accounting is need for proper medical and laboratory waste management