1. MEDICAL & LABORATORY
WASTE MANAGEMENT
Dr. Samwel V. Manyele
Medical Waste Management Research
Department of Chemical and Process Engineering,
University of Dar es Salaam

2. 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
Dr. S.V. Manyele, CPE, UDSM 2

3. 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 Dr. S.V. Manyele, CPE, UDSM 3

4. 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.
Dr. S.V. Manyele, CPE, UDSM 4

5. DEFINITION
1)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
Dr. S.V. Manyele, CPE, UDSM 5

6. 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
Dr. S.V. Manyele, CPE, UDSM 6

7. What properties make medical
& lab waste hazardous?
• Toxicity –
chronic, acute • Can it explode?
• Carcinogenicity • Will it corrode or
• Teratogenicity burn skin?
• Mutagenicity • Is it flammable?
Dr. S.V. Manyele, CPE, UDSM 7

8. Prepare for Legal
Compliance
• This is the key medical & lab
waste management
requirement.
• It is related to storage,
hauling, treatment, and final
disposal
Dr. S.V. Manyele, CPE, UDSM 8

9. Elements of Infectious Waste
Management
Identification of infectious waste
Segregation
Packaging
Storage
Transport and handling
Treatment techniques
Disposal of treated waste
Contingency planning
Staff training Manyele, CPE, UDSM
Dr. S.V. 9

10. Infectious Waste Treatment
Change 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)
Dr. S.V. Manyele, CPE, UDSM 10

11. Infectious Waste Treatment
Factors to consider while selecting treatment
method
Sterilization efficacy
Maintenance & operator skills
Air emission
Water emissions
Treated waste characteristics
Dr. S.V. Manyele, CPE, UDSM 11

12. 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.
Dr. S.V. Manyele, CPE, UDSM 12

13. Other treatment methods
Do not destroy the waste but does
destroy the pathogens.
Examples:
• Steam autoclave
• Microwave irradiation
• Chemical Treatment
• Radio frequency irradiation.
Dr. S.V. Manyele, CPE, UDSM 13

14. Pathogens in the medical waste
Reduce risks by eliminating modes of
transmission between humans and the
pathogens
Expose pathogens to temperatures
encountered in incineration
Exposure remains in survived fractions
(ash, smoke) and escape during
loading.
Apply testing protocols
Dr. S.V. Manyele, CPE, UDSM 14

15. 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
Dr. S.V. Manyele, CPE, UDSM 15

16. Inactivation levels
Viable Viable Reduction Inactivatio Time to %
cells cells at factor n levels achieve reduction
at t = 0 time t inactivatio
n level
106 105 10 1Log10 1D 90
106 104 100 2Log10 2D 99
106 102 10,000 4Log10 4D 99.99
106 100 =1 1,000,000 6Log10 6D 99.9999
Where D = decimal reduction time = 2.303/k
Dr. S.V. Manyele, CPE, UDSM 16

17. 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.
Dr. S.V. Manyele, CPE, UDSM 17

18. 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. Dr. S.V. Manyele, CPE, UDSM 18

19. Table 2. Recommended biological indicators
Vegetative Staphylococcus aureus (ATCC 6538)
Bacteria Pseudomonas aeruginosa (ATCC 15442)
Fungi Candida albicans (ATCC 18804)
Penicillium chrysogenum (ATCC 24791)
Aspergillus niger
Viruses Polio 2, Polio 3
MS-2 Bacteriophage (ATCC 15597-B1)
Parasites Cryptosporidium spp. oocysts
Giardia spp. Cysts
Mycobacteria Mycobacterium terrae
Mycobacterium phlei
Mvcobacterium bovis (BCG) (ATCC 35743)
Bacterial Bacillus stearothermophilus (ATCC 7953)
Spores
Bacillus subtilis (ATCC 19659)
Dr. S.V. Manyele, CPE, UDSM 19

20. 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.
Dr. S.V. Manyele, CPE, UDSM 20

21. Precautions
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.
Dr. S.V. Manyele, CPE, UDSM 21

22. Handling Chemical Characteristics
When 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)
Dr. S.V. Manyele, CPE, UDSM 22

23. The Chemical Wastes
Vapors, 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 waste
Plastics in the waste contributes
most of the Pb & Cd (thermo-
and photo-stabilizers)
Dr. S.V. Manyele, CPE, UDSM 23

24. Low-level radioactive waste
(LLW)
Sources:
Radiopharmaceuticals; nuclear medicine,
Radio- immunology procedures
Medical & research institutions
produce < 5% of the total volume of
LLW in USA
In Tanzania, 90% of these wastes come
from medical & research institutions.
Currently, there is no disposal sites for
LLW in TanzaniaManyele, CPE, UDSM
Dr. S.V.
(TRUE/FALSE?) 24

25. (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.
Dr. S.V. Manyele, CPE, UDSM 25

26. 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
Dr. S.V. Manyele, CPE, UDSM 26