Safety at NUS

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Safety at NUS
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Radiation Hazards
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What is radiation?

• Matter is composed of atoms. Some atoms are
• unstable. As these atoms change to become more
• stable, they give off invisible energy waves or
• particles called radiation.
• 2 types
• -Non-ionizing
• -Ionizing

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What is radiation? (contd)

• Non-ionizing radiation radiant energy is NOT
  capable of stripping electrons from atoms
• - E.g. infrared, visible light
• Ionizing radiation radiant energy is capable of
  removing electrons from their atomic structures
  (approx. gt10-12eV)
• - E.g. x-rays, gamma rays

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Ionizing Radiation

• Two fundamental types
• -Particulate radiation in the form of
  particles, e.g. alpha, beta, neutrons
• -Wave radiation in the form of
  electromagnetic wave, e.g. Gamma rays, X-rays

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Types of Radiation

• Alpha
• Identical to a helium nucleus (2 p and 2 n in one
  tightly bound particle)
• Beta
• Energetic electron ejected from the nucleus of an
  atom
• One neutron is converted to one proton and one
  electron

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Types of Radiation (contd)

• Gamma
• Electromagnetic radiation from nucleus
• X-ray
• Electromagnetic radiation from orbital electrons
• Neutrons

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Sources of radiation

• Naturally-occurring radiation accounts for
  approx. 80 of our exposure. Most of our exposure
  is to indoor radon, followed by radiation from
  outer space and from the earths crust.
• Since the discovery of radiation, people have
  benefited from the use of radiation in medicine
  and industry. Man-made sources of radiation
  account for about 20 of our total exposure to
  radiation.

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Sealed vs Unsealed sources
Sealed source Radioactive materials sealed inside
metal/plastic. Most sealed sources can be handled
without concern that the radioactive material
will be dispersed onto hands or clothing Unsealed
source Unsealed sources are usually liquids that
are applied directly and not encapsulated during
use. The contents of these unsealed sources are
readily accessible to the user. Most come in
liquid form, with potential for spills, splashes,
aerosolization, and vaporization. Stock vials may
not provide adequate shielding.
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Diff. between radiation radioactivity

• Radiation is the emission of energy from a
  source, either by particles or photons.
• There is a difference between Radiation and
  Radioactivity
• Radioactivity is radiation that is from a change
  in the nucleus of an atom, other forms of
  radiation are usually the emission of energy from
  a change in the electron orbits.

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Radioactivity

• The rate of radioactive decays is described by
  the nuclear disintegrations per unit time
• Amount of radioactive in Becquerels (Bq)
• 1 Bq 1 disintegration/second (SI unit)
• 1 Ci 3.7X1010 disintegrations/second (Older
  unit)

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Half-Life (T1/2)

• Time taken for the activity of a sample to halve
  as a result of radioactive decay
• A A0/2n
• Ao Original Activity
• A Activity at time t
• N is the number of half lives expired in time, t

• Activity of a vial of Tc-99m was 80 GBq, T1/2 for
  Tc-99m is 6 hours
• After 6 hours, one half life, A 40GBq
• After 12 hours, two half life, A20GBq
• After 24 hours, four half lifes, A5GBq

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Measurements of Radiation

• Common units or special units (US)
• -Roentgen (R)
• -RAD (Radiation Absorbed Dose)
• -REM (Roentgen Equivalent Man)
• -Curie (Ci)
• International units SI
• -Gray (Gy)
• -Sievert (Sv)
• -Becquerel (Bq)

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Two areas where units are used

• Units of activity
• -Quantity amount of radiation emitted from a
  radiation source
• Units of exposure (dose)
• -Quantity amount of radiation absorbed or
  deposited in a material

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Activity

• Quantity of a radioactive material present at a
  given time
• -It is the number of disintegrations or
  transformations of a given quantity of material
  in a given period of time
• Units Ci 3.7X1010 disintegration per second
  (dps)
• 1 Bq 1 disintegration/sec
• 3.7X1010Bq1 Ci
• 1 Ci2.22X1012 disintegration/min (dpm)
  amount of radioactivity in 1 gm of Ra 226

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Half-Life

• T½ Measure of radioactive decay
• Half-life
• -Physical
• -Biological
• -Effective
• Examples, Carbon-11 (20min), Sulfur-35 (88 days),
  Calcium-45 (165 days), Tritium (3H) (12.46 yrs),
  Carbon-14 (5730 yrs), Uranium-238 (4.5X109 yrs)

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Examples of Half-life

• If ..was worth only 36 billion dollars, and if
  he were to lose ½ his money each year, how long
  before he is only a millionaire? (t½ 1 yr)

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Dose

• Units (US)
• -Roentgen (R), RAD radiation absorbed dose,
  REM radiation equivalent man
• -1 R1 RAD1 REM if radiation weighting factor1
• Units (SI)
• -1 Gy 1 joule/kg 100 rads
• -1 Si 100 rem

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Exposure

• Photon flux related to amount of energy
  transferred to unit mass of air
• Dose unit
• -Roentgen (US)
• -No. of unit C/kggtCoulomb
• -Quantity of gamma or x-rays producing ions
  carrying a charge of 2.58X10-4C/kg air

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Absorbed dose

• Charge per unit mass
• -Any type of radiation
• -Any type of material
• Dose units
• - rad62.4X106 MeV/g
• - Gy100 rads

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Dose calculations

• DLa/d2 where
• Dabsorbed dose in rad/hr
• Lgamma ray constant (from table)
• aactivity in millicuries
• ddistance
• Calculate the absorbed dose in mrad per hr at 150
  cm from a 250 millicurie Cesium-137 source
• - DLa/d23.3X250/150236.7 mrad/hr at 150 cm

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Equivalent dose

• Absorbed dose multiplied by the radiation
  weighting factor (RWF) or quality factor (QF)
• RWF is the biological effectiveness of a
  radiation type
• Accounts for the type of radiation and its
  biological effects in human
• Units-rem

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Calculating rem

• Remrad X QF where
• QF 1 for x-rays, gamma rays and beta rays
• 3 for neutrons (fast)
• 10 for neutrons (slow)
• 20 for alphas
• A source of radium-226 produces 0.15 mrad per hr
  in a worker. Calculate rem dose in an 8-hr shift.
• Rem rad X QF0.15X20 (alpha)X824 rem/8-hr shift

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Summary

• Gy and rad measure Absorbed Dose
• Si and rem Equivalent Dose
• Bq and Ci Radioactivity

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Ionising radiation measurement

• Monitoring instruments
• -A large variety available
• -None universally applicable
• -Selection of appropriate detector is
  important

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Monitoring methods

• Film badges
• -Worn on the outside of clothes
• -Consists of small piece of photographic film
• Thermoluminescence detectors
• -Used in finger dosimeters
• -Amount of light given off is related to the
  absorbed amount of radiation
• Pocket dosimeter
• -Direct reading portable unit
• -Allows individual to determine radiation dose
  as they are working

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Ionising chambers

• Measure gamma, x-, beta-, alpha radiation
• Very useful and popular
• Convenient and accurate

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Geiger Mueller Counter

• Used for beta, gamma, x-ray radiation measurement
• Capable of detecting very small amount of
  radiation
• Uses an ionising chamber but filled with a
  special gas and greater voltage is supplied

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How Radiation Harm You?

• Ionizing properties of radiation
• Lead to molecular changes and form chemical
  species that are harmful to the chromosome
  material
• Harm can come from changes in construction and
  function of the cells.
• Radiation can cause
• Early death of the cell or prevention or delay
  of cell division
• Permanent modification which is passed on to
  daughter cells

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Biological Effects
Radiation
chromosome
Cell
Chemical bond break
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Biological effects of different radiation
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Deterministic Effects

• Below a certain dose, the proportion of cell
  damage from the exposure is not sufficient to
  affect the function of the organ or body and no
  observable effects as a whole
• Severity increases with dose
• Eg. 1 Gy can cause nausea and vomiting
• 5 10 Sv is sufficient to cause Bone Marrow
  Damage

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Stochastic Effects

• Probability of an effect occurring increase with
  dose
• Effects include cancer induction and hereditary
  effects in future generations
• This means that even low dose can potentially
  have ill effects its a statistical probability
• Zero threshold concept

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Working Safely with Radiation

• ALARA principle
• Time, distance and shielding
• Safe work practices

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ALARA

• Exposures are kept As Low Achievable As
  Reasonably Achievable / Allowable
• Formal ALARA program
• Keeping all doses, releases, contamination and
  other risks low
• Achieve 10 of applicable legal limits

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Methods of Achieving ALARA

• Time
• Distance
• Shielding

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Basic Radiation Protection

• Justification
• Benefit must outweigh risk
• Limitation
• Dose limits must not be exceeded
• Optimization
• ALARA, social and economic factors considered

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External radiation dosage

• - Explanation
• The dose accumulated by a person working in a
  area
• Dose Dose rate X Time

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External radiation dosage

• Calculation
• Dose limit is 400 uSv
• Dose rate is 20 uSv h-1
• Dose dose rate X time
• 400 20 X t
• t 20 hours

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Time Example

• Annual dose limit for rad worker is 20mSv/year.
  Assume 50 weeks/year, how much is the hourly
  exposure? Ans 0.01 mSv/hour
• How many hours can a worker spend in a week an
  area with a dose rate of 20 microSv/hour
• 20 mSv 20 mSv/year 1 year
• 20 mSv 20 µ Sv/hour time
• Time 1000 hour
• Hours/week 1000/50 20 hours

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Time Example

• If rad worker spends 35 hours per week in the
  area, what is the max allowable dose rate per
  week?
• 0.01 mSv/hr40 hr/week 0.4 mSv/week
• 0.4 mSv/week 1week/35 hr 0.114 mSv/hr
• 11.4 microSv/hr

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Time Example

• Dose limit for individual member of the public is
  1mSv/year. What is the max dose rate in the area
  which could be continuously occupied by the
  members of the public? 0.11 micro Sv/hour
• 1mSv/year 1 year/365 days 1 day/24 hour

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Distance

• Inverse square law
• D1r12 D2r22
• D Dose rate at distance, r
• R Distance from the radiation source
• Dose rate at 2m from a gamma source is 500 micro
  Sv/hour. Distance that will give dose rate of 10
  micro Sv/hour? 14.1m

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Shielding
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Safe Work Practices (contd)

• Rehearse operations without radioactive material
• Inform others in the area of the use of
  radioactive material
• Minimize the time spent near radioactive
  materials.
• Use remote handling tools like tweezers or
  forceps to handle stock vials.

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Safe Work Practices (contd)

• Do not handle the stock vial for a extended
  period of time
• Use appropriate shielding
• Minimize the amount of material handled. Only use
  what you need, put the rest away

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Safe Work Practices (contd)

• Make sure the material is properly contained.
• Drip trays lined with absorbent material
• Stabilize glassware to prevent it from tipping
• Dry powder use a glove bag or box
• Transport items in shielded secondary containers.

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Safe Work Practices (contd)

• Do not contaminate writing materials
• Segregate items used with radioactive materials
  with those used with non-radioactive materials.
• Protective clothing shall be worn when handling
  contamination may be expected.

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Safe Work Practices (contd)

• Personal with tears/breaks in skin should wear
  waterproof tape to seal such breaks or not
  manipulate radioactive material
• Personnel shall monitor themselves (and their
  work surfaces) for contamination after each use
  of radioactive material.

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Safe Work Practices (contd)

• Eating, drinking, smoking and mouth pipetting is
  prohibited
• Items that are routinely contaminated
  (centrifuges, water baths, tongs, etc) should be
  clearly labeled.
• Hands should be monitored and washed before
  leaving the lab.

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Waste Handling Process

• Store in a safe location with proper shielding
  until the waste has decayed to a low level
• Must be lt 1 microSv/hr or 0.1 mrem/hr
• Proper shielding
• Beta emitters Perspex enclosure
• Gamma emitters Lead shielding

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Waste Handling Process (contd)

• Place in secondary containers
• Proper labeling and designate the storage area
  with clear signages

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Radiation Waste Disposal in NUS

• Permitted types
• C14 (Licensing exemption limit (LEL) 100microCi)
• Tritium (1000microCi)
• I-125 (10microCi)
• P-32 (10microCi)
• S-35 (10microCi)

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Radiation Waste Disposal in NUS

• If mixtures of radioisotopes
• Sum of An/Mn is less than the LEL of the most
  active radionuclides
• An Activity of nuclide n,
• Mn LEL of nuclide n

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Radiation Waste Disposal in NUS

• Place waste inside Red Bag (can be obtained from
  Ms. Lisa Lui _at_ oshsec)
• Tape opening with Red Tapes (From Lisa)
• Fill up Yellow label and paste onto the Bag
• Fill up Form RAD01-01
• Low level biological-incineration
• Chemical Biological

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Radiation Waste Disposal in NUS

• Liquid Radiation Waste
• Absorbed into vermiculite at point of use and
  dispose off as solid waste
• All radioactive bags must be kept in secure and
  safe area
• OSHE will organize central collection every 4 to
  6 months depending on level at the departments
• Cost of disposal is borne by OSHE but this may be
  charged to individual departments in the near
  future

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Radiation Protection Act (Cap 262)

• Regulated by Centre for Radiation Protection
  (CRP) under Health Sciences Authority
• Subsidiary legislations
• - Radiation Protection (Non-Ionising)
  Regulations
• - Radiation Protection (Ionising) Regulations
• - Radiation Protection (Transport of Radioactive
  Materials) Regulations

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Radioactive Protection Act

• CRP has Director appointed by the minister
• Radiation Advisory Committee- to advise Minister
• Act focuses on Use, Manufacture, Sale of and
  Dealing with Radioactive Materials and
  Irradiating Apparatus
• You require to have a license
• Duties of licensees
• Disposal of radioactive waste
• Powers of Director Authorised Officers

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Radiation Protection (Ionising) Regulations

• Exemptions-details
• Licenses
• Age limit
• Condition for engaging in radiation work
• Arrangements for protection of workers
• Medical and radiological supervision
• Labeling of irriadiating apparatus and
  radioactive materials
• Storage

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What Is NIR?

• Energy waves of oscillating electric and magnetic
  fields traveling at the speed of light
• Energy levels not great enough to cause the
  ionization of atoms
• Includes spectrum of UV, IR, microwave (MW),
  radio frequency (RF), extremely low frequency
  (ELF) and visible light

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Why Is It Dangerous?

• Wide range of occupational settings
• Can pose a considerable health risk to exposed
  workers if not properly uncontrolled

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Examples of Non-Ionizing Radiation

• Extremely Low Frequency (ELF)
• Radiofrequency (RF) / Microwave (MW)
• Laser Hazards
• Infrared Radiation (IR)
• Visible Light Radiation
• Ultraviolet Radiation (UV)

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ELF

• Refers to an electromagnetic field having a
  frequency much lower than the frequencies of
  signals typically used in communications (From 1
  Hz to 300 Hz).
• Includes alternating current (AC) fields
• Most common ELF field is 60 Hz produced by power
  lines, electrical wiring, electrical equipment
• Two forms Static and ELF fields

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Health Hazards

• Potentially significant due to widespread use of
  electrical power at 50 60 Hz
• Much concern over consequence of long-term
  exposure to these fields
• One area is in computing applications where
  cathode-ray tube (CRT) displays are used

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Health Hazards

• ELF fields known to interact with tissues by
  inducing electric fields and currents
• Research has suggested possible carcinogenic,
  reproductive  and neurological effects
• Other health effects could include
  cardiovascular, brain and behavior, hormonal and
  immune system changes

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Safety and Precautions

• Inform about possible hazards
• Increase the worker's distance from the source
  (radiation fields often drop off dramatically
  within about 1m of the source)
• Stand back from electrical equipment, and work
  station CRT should be at least 0.5m away from
  eyes

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Safety and Precautions

• Use low-radiation designs wherever possible (for
  the layout of office power supplies, for example)
• Reduce exposure times. No action should be taken
  to reduce exposure if it increases the risk of a
  known safety or health hazard such as
  electrocution

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RF and MW Radiation

• Electromagnetic radiation
• RF - any frequency within the electromagnetic
  spectrum associated with radio wave propagation
• Microwaves are a specific category of radio waves
  that can be defined as radiofrequency energy
  where frequencies range from several hundred MHz
  to several GHz.
• From 3 kHz - 300 GHz (MW range from several
  hundred MHz to several GHz)

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Sources of RF and MW

• Traffic radar devices
• Heaters and sealers
• Wireless communications/cellular phones
• Radio transmission
• Radio antennas / masts
• Magnetic Resonance Imaging (MRI)

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Health Hazards

• RF and MW will damage tissue through heating at
  high intensities
• MW radiation is absorbed near the skin
• RF radiation may be absorbed throughout the body
• Parts of body most prone are the eyes and testes
  due to the relative lack of blood flow to
  dissipate the heat

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Health Hazards

• Levels encountered by the general public are far
  below levels deemed significant
• Workers working near transmission towers /
  antennas are exposed to large amounts of radiation

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Safety and Precautions

• Engineering Controls
• Sources of radiation should be properly shielded
• Devices which can produce acute thermal injuries
  (e.g., industrial MW ovens) should have
  interlocked doors
• Devices which produce high levels of stray RF
  radiation (e.g., induction heaters and dielectric
  heaters) should be operated remotely whenever
  possible

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Safety and Precautions

• Administrative Controls
• Exposure should not exceed the recommended
  exposure limits
• Areas where worker exposure is suspected to
  exceed the recommended limits should be surveyed
  to determine the exposure levels
• Needless exposure should be avoided
• Exposure times should be kept as short as
  reasonably possible

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Safety and Precautions

• Administrative Controls
• Potentially hazardous devices should be
  appropriately labeled
• Areas of excessive exposure around them clearly
  demarcated
• Notices with warnings and the necessary
  precautions should be posted
• Electrically-activated explosive devices should
  not be placed near sources of RF/MW radiation

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Safety and Precautions

• Administrative Controls
• RF/MW devices should not be used in flammable or
  explosive atmospheres
• Equipment sensitive to RF/MW should not be
  installed near sources of radiation
• Maintenance of devices used to produce RF/MW
  radiation should be done by qualified personnel.
  The equipment should be turned off whenever
  possible

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Safety and Precautions

• Controlling RF Shocks and Burns
• Metallic structures producing contact shocks
  should be electrically grounded and/or insulated
• Insulating platforms or shoes can be used to
  reduce energy absorption and currents to ground
• Workers should wear insulating gloves

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Safety and Precautions

• First Aid
• Remove worker from exposure area to a cool
  environment and provide cool drinking water
• Apply cold water or ice to burned areas
• Seek immediate medical attention
• Severe MW or RF overexposure may damage internal
  tissues without apparent skin injury, so a
  follow-up physical examination is advisable

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Lasers

• Stands for Light Amplification by Stimulated
  Emission of Radiation
• Produces an intense, highly directional beam of
  light is emitted
• Monochromatic one specific wavelength
• Coherent - each photon moves in step with the
  others

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Types of Lasers

• Commonly designated by the type of lasing
  material employed
• Solid-state lasers - lasing material distributed
  in a solid matrix
• Gas lasers use gases like helium and
  helium-neon
• Excimer lasers - (the name is derived from the
  terms excited and dimers) uses reactive gases,
  such as chlorine and fluorine, mixed with inert
  gases such as argon, krypton or xenon

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Types of Lasers

• Commonly designated by the type of lasing
  material employed
• Dye lasers - complex organic dyes, such as
  rhodamine 6G, in liquid solution or suspension as
  lasing media
• Semiconductor lasers - sometimes called diode
  lasers, are not solid-state lasers. Generally
  very small and use low power.

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Laser Classes

• Class I
• Laser systems that do not pose a hazard under
  normal conditions
• Examples include enclosed / interlocked lasers or
  lasers with low power output
• No warning label is required

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Laser Classes

• Class II
• Low power visible lasers or laser systems
• Not usually hazardous as natural human body
  reflexes reduces this
• Hazardous if viewed for prolonged periods of time
  (like many conventional light sources)
• If manufactured after 1976, will usually have a
  sign Caution Laser Radiation Do not stare
  into beam
• Sign must be clearly visible

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Laser Classes

• Class IIIA
• Lasers of laser systems that do not usually pose
  a hazard if viewed momentarily with the unaided
  eye
• Hazardous if viewed using collective optics

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Laser Classes

• Class IIIA
• Clearly visible sign with words Caution Laser
  Radiation Do not stare into beam or view
  directly with optical instruments
• Eye protection should be worn

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Laser Classes

• Class IIIB
• Lasers or laser systems that are hazardous if
  viewed directly, including viewing of reflections
  from smooth surfaces (diffused reflections are
  not hazardous)
• A clearly visible sign Danger Laser Radiation
  Avoid Direct Exposure to Beam must be in place
• Eye protection must be worn

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Laser Classes

• Class IIIB
• A clearly visible sign Danger Laser Radiation
  Avoid Direct Exposure to Beam must be in place
• Eye protection must be worn

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Laser Classes

• Class IV
• Lasers or laser systems that produce a hazard not
  only from direct viewing and reflections, but
  also from diffused reflections
• May produce fire and skin hazards
• A clearly visible which reads Danger Laser
  Radiation Avoid Eye or Skin Exposure to Direct
  or Scattered Radiation

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Laser Classes

• Class IV
• Capable of causing serious eye injury
• Should be enclosed if possible and operated
  remotely

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Health Hazards

• Common cause of laser-induced tissue damage is
  thermal in nature
• Tissue proteins are denatured / destroyed due to
  the temperature rise following absorption of
  laser energy
• Exposure can result in damage to the eye and skin
• Human eye is most vulnerable to injury than human
  skin

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Associated Hazards

• Hazards that are not associated with the beam
  itself
• Electrical Lethal electrical hazards from high
  power lasers.
• Chemical Eximer, dye and chemical lasers, and
  welding or cutting fumes
• Non-Beam Optical UV, Infra Red, or Visible Light

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Safety and Precautions

• Special Safety and Control Measures for
• Medical Applications
• Special training requirements
• Special equipment testing requirements
• Special medical surveillance requirements
• Laser treatment controlled areas
• Patient eye protections
• Evaluation of fiber delivery systems
• Ventilation systems

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Safety and Precautions

• Other Special Control Measures
• Laser demonstrations involving the general public
  or exposure of the general public to any laser
  beam hazards.
• Laser installation procedures
• Federal, state, or local requirements
• Personal protective equipment
• Warning signs, labels, and signal words in
  accordance with local standards.
• Electrical installations in compliance with local
  standards.

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Radiation Protection (Non-Ionising) Regulations

• Controlled apparatus
• (a) Ultraviolet sunlamps
• (b) Microwave ovens
• (c) Medical and industrial ultrasound apparatus
• (d) Magnetic resonance imaging (MRI) apparatus
• (e) Entertainment lasers
• (f) High power lasers

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Radiation Protection (Non-Ionising) Regulations
(contd)

• Licenses (4 types)
• Age requirement 18 years and
• Requirements for apparatus as mentioned
• Requirements for labeling
• Examples of label in laser apparatus
• (warning signs) (transparencies)

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Biological Hazards
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What are biohazards?

• Any material of biological origin capable of
  causing harm to human and its environment
• Examples
• Viruses
• Bacteria
• Fungi
• Human source material
• Animal source material, etc.

Viruses
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Biosafety Protection Principles

• Containment
• Safe methods for managing infectious materials in
  the laboratory to reduce or eliminate exposure of
  laboratory workers, other persons, and the
  outside environment.
• Include three elements
• 1. Laboratory practice and technique
• 2. Safety equipment (Primary containment)
• 3. Facility design (laboratory design)
• (Secondary containment)

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Safety Equipment

• Primary Barriers
• Includes BSC, Centrifuge cups, Personal
  protective equipment, enclosed containers, etc.
• Will only be effective if they are used properly

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Facility Design and Construction

• Labs must be designed and constructed based on
  the usage requirement
• Many design and construction factors
  ventilation, plumbing, access, work flow,
  construction material, treatment system, etc.
• Design and construction are not the most
  important factor but still an essential factor in
  biosafety

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Risk Assessment for Work withBiohazardous Agents
or Materials

• What is known about the agent or material?
• Is it associated with infections, toxicity, or
  allergies?
• What role does physical environment and work
  activity play in assessing risk?
• Are preventive measures available?
• Do barriers, personal protective equipment (PPE),
  pre- or post-exposure prophylaxis or
  immunizations offer protection?

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Biological Agent Characteristics

• Pathogenicity
• Virulence - degree of pathogenicity
• Host range
• Communicability

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Method of Transmission

• Direct Contact
• Direct transmission to receptive portal of entry
• Indirect Contact
• Vehicle-borne such as inanimate materials or
  objects (fomites)
• Vector-borne (arthropods)
• Airborne
• Dissemination of microbial aerosols to a suitable
  portal of entry

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Routes of Transmission

• Ingestion
• Inhalation
• Absorption
• Penetration of skin or membranes

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Other Risk Assessment Criteria

• Concentration of material to be used
• Quantity to be used
• Potential for aerosol generation
• Infectious dose
• Stability in the environment
• Ability to avoid host defence
• Type of work

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Other Risk Assessment Criteria

• Toxicity (microbial toxins)
• Enzymes (microbes produce coagulase, hemolysins,
  hyaluronidase)
• Allergenicity (agent or by-products animal
  dander, urine)
• Genetic modifications
• Biological/chemical/radiological mixtures and
  interactions

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Risk Group Classification (WHO)

• Pathogenicity
• Infectious dose
• Mode of transmission
• Host range
• Availability of effective preventive measures and
  treatments

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Risk Group 1

• Severity of Disease
• Unlikely to cause human or animal disease
• Host Range
• Human (healthy adult) and animals
• Individual Risk
• Low
• Community Risk
• Low

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Risk Group 2

• Severity of Disease
• Can cause disease, unlikely to be serious
• Effective treatment and preventive measures are
  available
• Host Range
• Human (healthy adult) and animals
• Individual Risk
• Moderate (potential hazard)
• Community Risk
• Low

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Risk Group 3

• Severity of Disease
• Can cause serious disease
• Does not ordinarily spread from one person to
  another
• Other criteria effective treatment and
  preventive measures are usually available
• Exposure route inhalation (often)

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Risk Group 3

• Host Range
• Human (healthy adult) and animals
• Individual Risk
• High
• Community Risk
• Low

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Risk Group 4

• Severity of Disease
• Likely to cause serious or lethal disease
• Can be readily transmitted from one individual to
  another
• Effective treatment and preventive measures are
  not usually available
• Transmission direct, indirect, inhalation

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Risk Group 4

• Host Range
• Human (healthy adult) and animals
• Individual Risk
• High
• Community Risk
• High

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Biosafety Levels

• VERY Important Biosafety Levels and Risk Groups
  are not always the same!!!
• Biosafety level Containment level
• Specifies
• Facility
• Safety equipment
• Microbiological and special practices

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Biosafety Levels (BSLs)Classification

• Biosafety level(s) refer to those conditions
  under which the biological agents can be safely
  handled ordinarily.
• Four laboratory biosafety levels (BSLs) are
  defined by CDC/NIH biosafety guidelines.
• Principal Investigator (PI) is specifically and
  primarily responsible for assessing the risks and
  appropriately applying the recommended biosafety
  levels.

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Biosafety Level 1

• Agent
• Well-characterized agents not known to cause
  disease in healthy adults
• Escherichia coli K12, Bacillus subtilis
• Basic lab facility work on the open bench
• Use standard microbiological practices
• No containment equipment is required

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Biosafety Level 2

• Agent
• Agents of moderate potential hazard to personnel
  and the environment
• Staphylococcus aureus, Hepatitis B virus,
  Salmonella species
• Basic lab facility, plus autoclave is available
• Use standard microbiological practices plus limit
  the access
• Containment equipment is used when aerosols are
  generated or concentrated preps and large volumes
  are handled

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Biosafety Level 3

• Agent
• Indigenous or exotic agents with potential for
  aerosol transmission that may cause serious or
  potentially lethal disease
• Mycobacterium tuberculosis, Coxiella burnetii,
  St. Louis encephalitis virus
• Containment facility
• Use standard microbiological practices plus
  controlled access
• Containment equipment, such as Class I or II
  biological safety cabinets (BSCs) are required
  for manipulations of viable material and
  additional PPE is required

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Biosafety Level 4

• Agent
• Dangerous and exotic agents that pose high risk
  of aerosol transmitted LAI and life threatening
  disease, or related agents with unknown risk of
  transmission
• Marburg, Congo-Crimean hemorrhagic fever

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Biosafety Level 4

• Maximum containment facility
• Standard microbiological practices plus clothing
  change, showers, and decontamination of all
  materials on exit from the lab
• Containment equipment, such as Class III BSCs or
  Class I or II BSCs in combination with one-piece
  positive pressure suits ventilated by a
  life-support system protected in conjunction by
  HEPA filtration

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Disinfection Procedures

• Why disinfect?
• to get rid of unwanted pathogenic microorganisms
• To eliminate - or at least reduce - exposure risk
• medical waste treatment
• spill cleanup
• minimization of nosocomial infections
• routine surface decontamination
• To eliminate contamination risk
• preparation of microbiological media supplies
• preparation of pharmaceutical production supplies
  and equipment
• preparation of food (surface sanitization)
• preparation of work area for cleanliness-critical
  tasks

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Some key disinfection terms

• sterilization - act or process, physical or
  chemical, that destroys or eliminates all forms
  of life, especially microorganisms
• disinfectant - an agent, usually chemical, that
  inactivates viruses or kills vegetative microbes
  but not necessarily resistant forms such as
  spores
• antiseptic - a substance that prevents or arrests
  the growth or action of microbes, either by
  inhibiting their activity or by destroying them
  (living tissue use)
• decontamination - disinfection or sterilization
  of contaminated articles to make them suitable
  for use
• sanitizer - an agent that reduces the numbers of
  vegetative bacteria only

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Resistance to disinfectants
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Classes of Disinfectant

• Chlorine
• Iodine
• Alcohol
• Phenolics
• Quaternary Ammonium Compounds
• Glutaraldehyde
• Formaldehyde
• Hydrogen Peroxide
• Chlorhexidine

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Transport and Storage

• Transport pointers
• Secondary container
• Planning ahead
• Spill control
• Storage
• Labeling
• Proper record
• Freezer management

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Biological Waste Handling

• Must have in place biological waste handling
  procedures in the lab
• Mixed waste hierarchy

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Waste Handling Pointers

• Use proper sharps bins
• Do not overfill 80 mark
• Use yellow bag with biohazard symbol
• Double bagged and seal securely
• Use secondary containers

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THE END