2&3. Hazards in biological laboratories: (electricity, fire, radiation and chemicals
i)Fire - fire triangle –
The average science lab is a particularly hazardous area when it comes to fire. Flammable liquids,
compressed and liquefied gasses, hazardous and reactive materials are all either in use or in store in the
lab. In addition, there are many sources of ignition available. In a fire triangle, a fire needs 3 things to
burn:
Fuel- something to burn eg oil
Oxygen- to maintain combustion
Ignition – something to start the fire eg excessive heat, electrical spark etc.
By removing any one of the 3 above, fire is prevented. Many fires obtain oxygen from the air where its
20% in volume. Fire extinguishers prevent oxygen being available to the fuel or ignition source.
The essence of fire prevention is to prevent the formation of triangle. Since air is present all the time,
the principle is to keep fuel and ignition sources apart.
Precautions for fire protection
In event of fire or explosion occurring, there should be a pre-arranged plan of the necessary action to be
taken. All personnel must be made aware and a fire drill carried out. The essential procedures include:
-Fire alarms
-Fire escapes
-Barriers
-Fire extinguishers
ii) electricity hazards
electricity is important in the lab as many appliances can only use electric power. However, it also
posses a number of hazards. Its misuse can cause serious injury, give shock that may be fatal or start
devastating fires.
A current of 1mA - causes a tingling sensation
6-10 - mA the let go current
10mA - produces muscular contraction which does not allow even to throw away the current
carrying object
20-25 – death- causes irregular contraction of the heart thereby stopping pumping
Reasons behind electrical mishaps
-improper wiring
- improper choice of fuse
- choosing wire of improper rating
- accidental touches
- break in earthing system
- improper operation/use of unconventional tools
To prevent any hazard from electricity, one should follow a safe conduct. Ie proper use of adaptors,
plugs and also the cable and flex routing. One should keep checking every plug, socket and lead in the
lab from wire to wire. Earthing is also important while dealing with electricity. It is also essential to learn
how a piece of equipment is earthed and also to test the connections.
It is compulsory for lab assistants to be sure of the colour code of electricity wires.
a) Wiring a plug – which wires are connected to which terminus; Earth-green: Live-red: Neutral-black
b) Fuse – a safety device or a wire metal in a cut out which may be fused by and excessive current.
A regular (annual) thorough check of plugs, sockets, and leads should be a standard practice in the lab.
, iii) Gas hazards
Gas hazards in a lab arise from liquefied petroleum gasses (LPG) and other compressed gasses.
Pressurized gas cylinders are widely used in all labs and many contain toxic or flammable gasses.
Precautions necessary in order to minimize gas hazard in the laboratory
1) Ventilation: it is a good practice to ventilate a laboratory as soon as it is opened to disperse
any accumulations of vapour, dust and gas. In any emergency increased ventilation is
essential.
2) Respirators: should be available where there is risk of gas hazards.
3) Where there is risk of explosion, due to gas, elimination of ignition is essential. This can be
done through;-
i) Use of spark free electrical switches
ii) Elimination of all sources of sparking from impact/friction
iii) A thorough warning system
iv) Banning of all electric motor
v) No experiments/or work with flame.
4) Large cylinders should always be clamped vertically to prevent them from toppling over
5) Cylinders may be stored in a open but should be protected from water, to avoid rusting and
from extreme temperatures (temp should not be beyond 50 0c)
6) Care must be taken while moving cylinders. They should never be rolled, dragged or slid.
Use of a trolley is recommended.
7) The valve protection cap should not be removed if the gas is not be used. Stiff cylinder valves
must be opened carefully with hand pressure and not forced.
8) When the gas has to be passed through a liquid always use a check valve or a trap to prevent
back suction of the liquid into the cylinder.
9) Use suitable cylinders so that the gas exhaust within a reasonable period of time.
10) Oil or grease must never be used on lines, releasing valves or other equipment for oxygen
cylinders as this can cause explosions.
iv) Radiation Hazards
the hazardous nature of radiations is manifested on its integration with matter. They can therefore be
divided in to:
(i) ionizing and
(ii) non ionizing radiations
Ionizing radiations changes the atomic structure of a substance and can be classified into: Alpha (), Beta
(), Gamma ()
The international symbol of ionizing radiations is usually black on a yellow background.
The radiations can cause cancer, genetic mutations, skin reddening in human. Effect on reproductive
cells are cumulative and genetic damage may result.
Non-ionizing radiations cannot change the nature of the atom but can be highly hazardous.
They include microwaves, UV and infra-red radiations, ultrasonics, light (from lasers) etc.
UV light has higher energy than visible light. Hydrogen lamps, deuterium lamps, are common in
the lab. One should always avoid contact with these radiations.
, Microwaves – the hazard of microwaves is primarily due to their invisible nature and ability of the body,
particularly the eyes to absorb microwaves without any sensation. This easy absorption of radiation by
the body and the high thermal effects of microwave can cause severe damage to internal organs.
-People with metal plates, steel implant, heart peacemaker etc can suffer severe injury from microwave
radiation.
-The doors of microwaves should always be properly shut to avoid leakage of dangerous amounts of
microwave energy.
Precautionary measures against ionizing radiations
1) Avoid contact with skin by ;-
a) Wearing protective gloves and a lab coat
b) Transferring chemicals in a fume cupboard or in manipulator glove box with a spatula of
forecepts.
c) Using safety bulbs while pipetting. Avoid licking.
2) Confine the work with radioactive materials in one area of the lab e.g. a fume cupboard and
always set up warning signs.
3) Glassware to be used should be kept surely for this purpose and stored separately to guard against
accidental contamination.
4) All bottles containing these materials should be labeled with a recognizable label.
5) Any issuance of radioactive material should be properly recorded i.e. date and time and full
names.
6) The quantities used should be checked and properly accounted for.
7) The reminder should be returned to a securely locked and suitably shielded cupboard in the
stores. The cupboard should be properly labeled and used only for storing radio-active materials.
A special notebook should be kept alongside and all details filled.
8) Hands should always be washed thoroughly and disposable towels used after working with these
materials. Geiger counter should also be used to ensure that no radio-active remains on the skin
9) Use plenty of water if disposing of permitted quantities (upto100g) of uranium or thorium salts.
iv Chemical hazards
Chemicals are present in all laboratories. It is always good to consider chemicals toxic and flammable
unless one has definite information regarding its nature. The hazardous chemicals are generally
poisonous, explosive and flammable type. In the lab, human contact with chemicals can take place in the
following ways:
- direct contact from spills or improper handling
- inhalation of vapor, fumes or dust
- ingestion i.e. the oral route
- indirectly e.g. highly inflammable liquids may catch fire and severe burns
Precaution should be strictly followed while storing and handling these chemicals. The classification of chemical
hazards by the UN committee of experts on the transport of dangerous goods has been widely adopted. It recognizes
9 classes. For hazard identification, all the hazard classes (with the exception of class 9) has a distinctive diamond
i)Fire - fire triangle –
The average science lab is a particularly hazardous area when it comes to fire. Flammable liquids,
compressed and liquefied gasses, hazardous and reactive materials are all either in use or in store in the
lab. In addition, there are many sources of ignition available. In a fire triangle, a fire needs 3 things to
burn:
Fuel- something to burn eg oil
Oxygen- to maintain combustion
Ignition – something to start the fire eg excessive heat, electrical spark etc.
By removing any one of the 3 above, fire is prevented. Many fires obtain oxygen from the air where its
20% in volume. Fire extinguishers prevent oxygen being available to the fuel or ignition source.
The essence of fire prevention is to prevent the formation of triangle. Since air is present all the time,
the principle is to keep fuel and ignition sources apart.
Precautions for fire protection
In event of fire or explosion occurring, there should be a pre-arranged plan of the necessary action to be
taken. All personnel must be made aware and a fire drill carried out. The essential procedures include:
-Fire alarms
-Fire escapes
-Barriers
-Fire extinguishers
ii) electricity hazards
electricity is important in the lab as many appliances can only use electric power. However, it also
posses a number of hazards. Its misuse can cause serious injury, give shock that may be fatal or start
devastating fires.
A current of 1mA - causes a tingling sensation
6-10 - mA the let go current
10mA - produces muscular contraction which does not allow even to throw away the current
carrying object
20-25 – death- causes irregular contraction of the heart thereby stopping pumping
Reasons behind electrical mishaps
-improper wiring
- improper choice of fuse
- choosing wire of improper rating
- accidental touches
- break in earthing system
- improper operation/use of unconventional tools
To prevent any hazard from electricity, one should follow a safe conduct. Ie proper use of adaptors,
plugs and also the cable and flex routing. One should keep checking every plug, socket and lead in the
lab from wire to wire. Earthing is also important while dealing with electricity. It is also essential to learn
how a piece of equipment is earthed and also to test the connections.
It is compulsory for lab assistants to be sure of the colour code of electricity wires.
a) Wiring a plug – which wires are connected to which terminus; Earth-green: Live-red: Neutral-black
b) Fuse – a safety device or a wire metal in a cut out which may be fused by and excessive current.
A regular (annual) thorough check of plugs, sockets, and leads should be a standard practice in the lab.
, iii) Gas hazards
Gas hazards in a lab arise from liquefied petroleum gasses (LPG) and other compressed gasses.
Pressurized gas cylinders are widely used in all labs and many contain toxic or flammable gasses.
Precautions necessary in order to minimize gas hazard in the laboratory
1) Ventilation: it is a good practice to ventilate a laboratory as soon as it is opened to disperse
any accumulations of vapour, dust and gas. In any emergency increased ventilation is
essential.
2) Respirators: should be available where there is risk of gas hazards.
3) Where there is risk of explosion, due to gas, elimination of ignition is essential. This can be
done through;-
i) Use of spark free electrical switches
ii) Elimination of all sources of sparking from impact/friction
iii) A thorough warning system
iv) Banning of all electric motor
v) No experiments/or work with flame.
4) Large cylinders should always be clamped vertically to prevent them from toppling over
5) Cylinders may be stored in a open but should be protected from water, to avoid rusting and
from extreme temperatures (temp should not be beyond 50 0c)
6) Care must be taken while moving cylinders. They should never be rolled, dragged or slid.
Use of a trolley is recommended.
7) The valve protection cap should not be removed if the gas is not be used. Stiff cylinder valves
must be opened carefully with hand pressure and not forced.
8) When the gas has to be passed through a liquid always use a check valve or a trap to prevent
back suction of the liquid into the cylinder.
9) Use suitable cylinders so that the gas exhaust within a reasonable period of time.
10) Oil or grease must never be used on lines, releasing valves or other equipment for oxygen
cylinders as this can cause explosions.
iv) Radiation Hazards
the hazardous nature of radiations is manifested on its integration with matter. They can therefore be
divided in to:
(i) ionizing and
(ii) non ionizing radiations
Ionizing radiations changes the atomic structure of a substance and can be classified into: Alpha (), Beta
(), Gamma ()
The international symbol of ionizing radiations is usually black on a yellow background.
The radiations can cause cancer, genetic mutations, skin reddening in human. Effect on reproductive
cells are cumulative and genetic damage may result.
Non-ionizing radiations cannot change the nature of the atom but can be highly hazardous.
They include microwaves, UV and infra-red radiations, ultrasonics, light (from lasers) etc.
UV light has higher energy than visible light. Hydrogen lamps, deuterium lamps, are common in
the lab. One should always avoid contact with these radiations.
, Microwaves – the hazard of microwaves is primarily due to their invisible nature and ability of the body,
particularly the eyes to absorb microwaves without any sensation. This easy absorption of radiation by
the body and the high thermal effects of microwave can cause severe damage to internal organs.
-People with metal plates, steel implant, heart peacemaker etc can suffer severe injury from microwave
radiation.
-The doors of microwaves should always be properly shut to avoid leakage of dangerous amounts of
microwave energy.
Precautionary measures against ionizing radiations
1) Avoid contact with skin by ;-
a) Wearing protective gloves and a lab coat
b) Transferring chemicals in a fume cupboard or in manipulator glove box with a spatula of
forecepts.
c) Using safety bulbs while pipetting. Avoid licking.
2) Confine the work with radioactive materials in one area of the lab e.g. a fume cupboard and
always set up warning signs.
3) Glassware to be used should be kept surely for this purpose and stored separately to guard against
accidental contamination.
4) All bottles containing these materials should be labeled with a recognizable label.
5) Any issuance of radioactive material should be properly recorded i.e. date and time and full
names.
6) The quantities used should be checked and properly accounted for.
7) The reminder should be returned to a securely locked and suitably shielded cupboard in the
stores. The cupboard should be properly labeled and used only for storing radio-active materials.
A special notebook should be kept alongside and all details filled.
8) Hands should always be washed thoroughly and disposable towels used after working with these
materials. Geiger counter should also be used to ensure that no radio-active remains on the skin
9) Use plenty of water if disposing of permitted quantities (upto100g) of uranium or thorium salts.
iv Chemical hazards
Chemicals are present in all laboratories. It is always good to consider chemicals toxic and flammable
unless one has definite information regarding its nature. The hazardous chemicals are generally
poisonous, explosive and flammable type. In the lab, human contact with chemicals can take place in the
following ways:
- direct contact from spills or improper handling
- inhalation of vapor, fumes or dust
- ingestion i.e. the oral route
- indirectly e.g. highly inflammable liquids may catch fire and severe burns
Precaution should be strictly followed while storing and handling these chemicals. The classification of chemical
hazards by the UN committee of experts on the transport of dangerous goods has been widely adopted. It recognizes
9 classes. For hazard identification, all the hazard classes (with the exception of class 9) has a distinctive diamond
