Skip to content
Physics and Astronomy
Home School documents Safety Manual   8. Hazardous Substances (COSHH)
Back to top

School of Physics Safety Manual


COSHH procedures

The Control of Substances Hazardous to Health Regulations 1988, 1994, 1999 & 2002 are designed to protect workers or others against substances considered hazardous to health in the workplace. COSHH assessments must be completed for any process or procedure that involves the use of hazardous substances. Hazardous substances may be found in nearly all working environments. Their effects may include the following and others:

·         Poisoning through ingestion, inhalation or skin absorption, for instance, losing consciousness or death as a result of being overcome by toxic fumes

·         Eye irritation or loss of sight from eye contact

·         Skin irritation or dermatitis from skin contact

·         Asthma as a result of developing an allergy to substances used at work

·         Cancer or other mutagenic effects, which may appear long after the exposure to the chemical that caused it

·         Infection from bacteria and other micro-organisms

Before carrying out a procedure with hazardous materials (including micro-organisms) any risk must be identified and assessed. It is the responsibility of the Supervisor and the laboratory worker to jointly assess the hazards associated with their work. Except in the very low risk situations it will be necessary for the assessment to be in the written form using a COSHH assessment pro forma. The process assessor and the process supervisor must sign the assessment form.

The process supervisor may delegate the task of assessment but s/he cannot delegate the supervisory responsibility. The process supervisor has executive control of and health and safety responsibility for the process and s/he must ensure that the assessment is complete and appropriate then sign it. The main findings of this assessment must be recorded in writing and then reviewed if there has been a significant change in the work. It is mandatory, BEFORE work is commenced, that the assessment is recorded and a copy is held locally in laboratory master records of COSHH assessments.

The School Safety Group will review selected COSHH assessments to assure that hazards have been properly identified and the appropriate control measures are in place to minimise risk.

The forms are available from the School COSHH Adviser or from the documents page of the University Health and Safety website.

COSHH procedures require the following steps are taken in the assessment, carried out by the person with the most knowledge and experience of the process, i.e. the process assessor. The assessor should carry this out jointly with the process supervisor.

Step 1. Identify the hazardous substances used or created by your procedure. What is the hazardous substance? Is it:

  • Substances or mixtures of substances classified as dangerous by the Chemicals (Hazard Information and Packaging for Supply) Regulations 1994 (as amended) (CHIP). These substances can usually be identified by their hazard-warning label and should have a material safety data sheet.
  • Substances with occupational exposure limits (OEL). These are published in the HSE Occupational exposure limits publication EH40 available in the Safety Office.
  • Biological agents and other micro-organisms directly connected with work.
  • Any kind of dust in a concentration specified by COSHH.
  • Any other substance, which has comparable hazards to people’s health, but which for technical reasons, may not have a hazard label eg some pesticides, medicines etc.

There are a number of other materials that are not actually covered by COSHH, such as asbestos, radioactive materials, lead and scheduled materials: these are covered by their own regulations. However, an assessment must be conducted.

Step 2 Consider the risk these substances present to people’s health. Assessing the risk involves making a judgement of how likely it is that a hazardous substance will affect someone’s health. How much of the substance is used? How could people be exposed to it? Who could be exposed to the substance and how often?

Step 3 If you identify significant risks then decide what precautions are needed to remove or reduce those risks to an acceptable level. What control measures are required? What are the first aid measures in case of an accident? What are the disposal methods?

Step 4 Ensure that control measures are used and maintained so that exposure to hazardous material is prevented or adequately controlled. This may involve changing the process so that the hazardous material is not needed or replacing it with a safer form. If prevention is not practical then the control measures must be improved so that exposure is adequately controlled and OELs are not exceeded.

Workers should be properly informed, trained and supervised. For certain very hazardous materials, exposure must be monitored and there should be health surveillance, the use of these materials is not permitted without prior consultation with the School Safety Officer. Any control measures that are used must be maintained and tested eg the fume cupboards are tested and serviced by Buildings and Estates Division. Defects must be reported to the School Safety Officer.


Bottles. All bottles of chemicals must be clearly and correctly labelled, and only those chemicals in use or likely to be required in the near future should be kept in the research laboratories. Over-labelling of original manufacturers labels is forbidden. Labelling must not be liable to facile removal eg on spillage of contents or splashing with solvent/water.

Mercaptans/Thiols.The School is obliged to report the use of such chemicals to other areas of the campus to avoid confusion over possible gas leaks. On any occasion, before handling mercaptans/thiols, workers must report their intention to the School Safety Officer.

Handling of Potentially Hazardous Air/Moisture-sensitive Compounds. Any research worker intending to use a potentially hazardous air/moisture-sensitive compound (eg organolithium reagents) must discuss the appropriate techniques for safe handling with their supervisor and fill out a COSHH Assessment form before starting the work. A copy of the Aldrich Technical Bulletin AL-134 “Handling Air-sensitive Reagents” must be consulted.

Rapidly toxic materials. May only be handled in the presence of at least one other experienced worker.

Inorganic Cyanides. Inorganic cyanides are controlled substances and will only be issued on presentation of a fully completed COSHH assessment form, which has been signed by the Research Supervisor and the School Safety Officer. A cyanide antidote kit must be obtained for the duration of the work. Only the required amount for the risk-assessed reaction is obtainable and residues must be destroyed immediately after use. Records of use must be kept.

S1 poisons and other controlled substances. The use of poisons, controlled substances and other forensic products under Schedule 1, 2, 3 and 4 are controlled through the Home Office. Many can only be obtained using special ordering procedures. Scheduled substances may only be ordered by academic staff, post doctoral research personnel and certain trained technical staff. All scheduled substances must be stored under lock and key and records of use must be kept. Their use must be subject to risk assessment as above. Some examples of S1 Poisons and Red list of proscribed substances are:

Arsenic and its compounds (except those containing less than 0.0075% As)

Aldrin Atrazine

Azinphos-methyl Bromomethane

Cadmium and its compounds Carbon Tetrachloride

Dieldrin DDT

Dichlorvas 1,2-Dichloroethane

Endosurfan Endrin

Fenitrothion Fluoroacetic acid and its salts

Hydrogen cyanide and cyanide salts gamma-Hexachlorocyclohexane

Hexachlorobenzene Hexachlorobutadiene

Mercury and its compounds Malathion

Nicotine and its salts Pentachlorophenol

Polychlorinated Biphenyls Simazine

Trichlorobenzene Tributyltin compounds

Triphenyltin Trifluralin

EC regulation on Drug Precursors. Under 2005 EC regulations the purchase of certain drug precursor chemicals requires a licence. The use of these materials must be recorded and a return must be completed for the Home Office. Further details are available from the School COSHH Adviser.

Chemical Weapons Convention. Under the Chemical Weapons Convention, the importation, use and production of certain chemicals and precursors must be recorded. There are restrictions on placing orders for these chemicals. Further details are available from the School COSHH Adviser.

Working with Insects or other Livestock. Persons working with insects are at risk of developing allergic reactions. These reactions can be skin rashes, itchy eyes, and runny nose but if severe may lead to more serious conditions such as asthma. Suitable precautions must be taken to reduce these risks including the use of facemasks conforming to FFP2. A COSHH assessment must be carried out.

Micro-organisms. Micro-organism, cell culture, or human endoparasite, including any which have been genetically modified, which may cause any infection, allergy, toxicity or otherwise create a hazard to human health must be assessed under COSHH. Such materials are also subject to the rules on handling micro-organisms.


Laboratory workers must be aware of the hazard associated with solvents; many are highly flammable and toxic and therefore should also be assessed under COSHH.

  • Most solvents are very volatile and so may easily be inhaled and will often cause drowsiness even if they are not toxic. Some can cause irritation or dermatitis if spilt on the skin.
  • Solvents should be stored in flameproof cabinets containing metal trays capable of retaining at least 110 per cent of the contents of the largest container stored. Large quantities must not be stored in the open laboratory. No more than 50 litres of highly flammable liquids may be stored in any one place.
  • Flammable and non-flammable solvents should not be stored together.
  • Flammable solvents should not be stored in refrigerators or freezers unless these have been spark-proofed.
  • Never put solvents for disposal down the sink.
  • As there is a real possibility of explosion of waste acetone and chloroform in the presence of alkali, ACETONE should only be added to the blue labelled waste bottles; if for some reason it is contaminated, then it should be sent for disposal in a separate container clearly labelled ‘Do not mix with other waste solvent’. Waste solvent should be separated into bottles of:
      • Acetone
      • Halogenated waste solvent (Chloroform, dichloromethane etc) and
      • Non-halogenated waste solvent (ethanol, ether etc)
  • Winchesters of solvents should be transported around the building using the carriers available for them and not carried in the hand.
  • Winchesters must not be left on the floor, on top of shelves or on reagent bottle shelves and they should not be kept on bench working surfaces for longer than necessary.
  • In general, waste solvent which contains a high concentration of acid or base should not be indiscriminately added to general waste solvent containers but disposed of separately.
  • Decompose reactive materials before placing in waste solvent bottles.


  • A cryogenic fluid is normally defined as one which is manufactured, stored, handled or processed at temperatures at or below 188 K (-85°).
  • Liquid nitrogen, helium and other cryogenics including solid CO2 must only be stored or conveyed in approved Dewar containers. Sealed containers must never be used due to build-up of dangerous pressure.
  • Care should be taken when handling cryogenic liquid storage Dewars. Avoid mechanical shock and damage to the vessel’s vacuum insulating jacket. Breakdown of the insulation will cause rapid boil-off of the liquid contents, producing large quantities of gas and a possible increase in pressure within the vessel.
  • Liquid helium Dewars should not be tilted.
  • Dewars should only be used for the specific liquids for which they are designed.
  • Persons transferring liquid nitrogen and other cryogenics from storage containers to liquid nitrogen refrigerators or Dewar flasks (including small vacuum flasks) must use facemasks or goggles, and suitable gloves.
  • Dry gloves should always be worn when handling anything that is or may have been in contact with cold liquids or vapour. Gloves should be a loose fit so that they are readily removed should liquid splash on to them or into them.
  • Attention is drawn to the need for adequate ventilation when using liquid nitrogen and other cryogenics including solid CO2. Never remain in a small enclosed space or travel in a lift with a Dewar of liquid nitrogen or other cryogenic material. Such area should be fitted with an oxygen depletion monitor. Liquid nitrogen and helium, although non-toxic, produce large quantities of gas which can cause an oxygen deficient atmosphere and asphyxiation.
  • Open transfers of cryogenic liquids and venting or purging operations should be carried out in well ventilated areas.
  • Exposure of the skin to low temperature can produce effects on the skin similar to a burn. Naked or insufficiently protected parts of the body coming into contact with very cold uninsulated pipes or vessels may stick fast by virtue of the freezing of the available moisture and the flesh may be torn on removal. Protective clothing for the handling of low temperature liquefied gas serves mainly to protect against frost burns.
  • Prolonged exposure to cold can result in frostbite. Prolonged inhalation of cold vapour or gas can damage the lungs. Cryogenic liquids and vapour can damage the eyes.
  • The low viscosity of cryogenic liquids means that they will penetrate woven or other porous materials much faster than for example water.

Compressed gases and gas cylinders

It is recommended that compressed gas should be sited outside buildings and distributed to points of use by means of fixed piped systems where this is reasonably practicable. The very minimum of flexible couplings should be used at each end. A suitable location for the cylinders should be chosen in a well-ventilated position remote from sources of ignitions, sources of fire-hazard (e.g. storage of flammable material) and building openings, the cylinders being safely supported, physically protected and the manifolds of good engineering design.

The number of cylinders inside laboratories should be kept to the smallest reasonably practicable number. Spare cylinders should be kept in the storage compound.

Only qualified technicians are authorized to handle compressed gas cylinders. Correct handling procedures are important to avoid damage to cylinders or injury to personnel. After being moved and before being put into use, it is important to carry out routine checks that the identification markings on cylinders are correct, the cylinders are safely installed and that the valves, regulators and other ancillary equipment are intact.

One of the main dangers is over-pressurisation of the cylinder in the event of a fire. This is particularly so when the gas has liquefied under pressure. Cylinders should be stored away from any source of heat such as boilers etc and should always be sited at a safe distance from other high fire risks.

The hose and hose connections are the weakest links in the system and failure of these is a known cause of fire and explosions. So far as is practicable gases should be distributed through suitable fixed metallic pipework. When flexible gas pipes are necessary they should be suitable for the duty intended and preferably be of metal or metal armoured type. Pipes should be as short as reasonably practicable and protected from possible physical heat or corrosion damage. Flexible hoses should be replaced periodically in accordance with the manufacturer’s advice.

The following general points apply.

  • Toxic or asphyxiant gases such as CO2 can build up in confined spaces.
  • Compressed gas cylinders are colour coded according to the gas contained. Cylinders containing flammable gases are red or part red and have a left-handed thread; non-flammable gas cylinders have a right hand thread for fitting of regulators.
  • Gas regulators should be fitted by trained personnel only, training must be provided for new research workers before they change cylinder regulators.
  • Never over-tighten regulators when fitting and do not lubricate threads,
  • Cylinder colours, valve threads or markings, should never be interfered with.
  • Cylinders must be stored or used upright and strapped to a secure support away from heat.
  • Cylinders should only be moved using the appropriate equipment. Safety shoes and cylinder trolleys are to be used, available from stores. Laboratory workers are required to move gas cylinders; qualified technicians will assist or advise when available.
  • Regulators should only be used for the gas identified on the regulator.
  • Gases which assist fire, eg oxygen, should be stored separately to flammable gases.
  • The door to the laboratory should be labelled with the gases in use to inform fire fighters in the event of a fire.
  • Cylinders not in regular use should be returned to the stores.

Personal Protective Equipment (PPE)

Research workers must make full use of the safety equipment available and have the requisite items at hand before commencing a potentially dangerous experiment.

PPE refers to equipment such as clothing, respirators, helmets, ear protectors, safety boots and eye protectors and gloves required for use in hazardous situations. PPE such as ear protection and filter respirators should be considered as the “last resort” once all other measures to reduce a risk to acceptable levels have been taken. Doing the job by a safer method should always be considered first. PPE must be suitable for the risks involved and must be maintained (including cleaned) in an efficient state and working order. Under the latest COSHH regulations, filter respirators must be tested for face fit.

Ensure that the appropriate type of disposable glove is worn for a given application – for example nitrile gloves may not be the best choice for many organic solvents.

When working with micro-organisms, a laboratory coat with side fastenings is recommended. This coat must be kept separate from other lab coats and outside clothing.

Eye protection must be chosen that is appropriate to the risk, visors should be used when handling large quantities of corrosive or hazardous materials but safety spectacles may be used for small quantities. Eye protection to BS EN 170 is suitable for use when there is a risk of UV radiation.

British and new European standards cover the specification for PPE in given situations.

Prevention of Fire and Explosion – general comments

The major risk of fire and explosion in laboratories is caused by the use of unsuitable equipment in explosive atmospheres or in areas where quantities of flammable vapour are present. In such an environment, it is essential that non-sparking or spark-proof apparatus is employed and that apparatus with moving parts should not be run in such a manner as to overheat. If such a fire should arise, switch off the apparatus and use the appropriate extinguisher, i.e. a CO2 extinguisher or dry powder extinguisher if a fire involves solvents. Under no circumstances should water or foam extinguishers be used.

Apparatus containing heating elements used for heating liquids etc should not be allowed to overheat and should remain covered by the liquid. It is preferable, where possible, to use the modern type of fail-safe connection with an ejector plug or fusible link.

Do not use immersion heaters of water-type for heating baths of fluids other than water.

To reduce fire hazard, stocks of flammables in laboratories should be kept to a minimum. If materials requiring special fire-fighting materials are stored in the laboratory, a suitable notice showing the correct fire-fighting instructions should be displayed on the door of the laboratory.

Definitions.The flash point is the temperature at which a substance gives rise to an ignitable vapour. If a substance is cooled below its flash point, the danger of ignition through the vapour reaching nearby flames, cigarettes, sparks or hot surfaces is much reduced. The minimum ignition temperature is that at which the vapour will spontaneously catch fire in air. Thus if vapour from a liquid at room temperature is carried by a draught into contact with a surface at a temperature above the ignition temperature the vapour may ignite and burn back to ignite the liquid. The minimum ignition energyof a flammable mixture of given composition and at a specific temperature and pressure id that below which ignition cannot be produced: operation below this level is the underlying principle of intrinsically safe equipment.

Toxic and Injurious Chemicals – General Comments

All chemical, especially organic substances, should be regarded as potentially hazardous unless they are known to be otherwise. Many substances which are not obviously corrosive or toxic can act as cumulative poisons. Most chemicals can be handled by simple methods provided that a little common sense is used. However, the well known action of dusts, vapours and oils in causing lung, skin and other diseases must be kept in mind. A surprisingly large number of substances are capable of causing diseases to develop after a period of apparent immunity e.g. asbestosis, cancer.

Care should be taken to avoid inhalation of vapours, ingestion of liquids and solids, and all unnecessary contact with the skin. Easting a drinking, smoking, application of cosmetics and sucking pencils can all lead to accidental ingestion or skin absorption. The prime preventive against accidental contamination is good housekeeping. Use of fume cupboards, and the wearing suitable protective equipment including goggles should always be used wherever appropriate to minimise the risk to personnel.

Chemical Storage hazards

Chemicals should be stored in such a way as to minimise the risk of accidental contact between incompatible chemicals, which could arise from breakage, spillage or fire. The table below provides a list (not exhaustive) of chemicals that need to be segregated on the grounds of potential reactive or toxic hazard. It is the responsibility of those working with chemicals to ensure they have assessed these risks and have stored all chemicals appropriately.

Ideally, fume cupboards should never be used for the storage of chemicals due to the very real risk of spillage. It must always be remembered that a fume cupboard is a working environment and those located in the Biophysics laboratory are a School resource – ensure your safety and the safety of others by not storing chemicals in these fume cupboards. Occasionally however, the storage of material in fume cupboards may be unavoidable, but if the chemicals must be in clearly labelled containers, with all potential hazards clearly indicated and with all containers placed in a tray in order to contain any accidental spillage.

Poorly labelled samples and chemicals pose an unacceptable risk to everyone and will NOT be tolerated.

List of reactive chemical hazards


(NOTE: this list is NOT complete, indicative only; it is YOUR responsibility to check reactive hazard risks)


The substances in the left hand column must be stored and handled so that they can not accidentally come into contact with the corresponding substances in the right hand column under uncontrolled conditions because violent reactions may occur. IT IS ESSENTIAL THESE CHEMICALS ARE SEGREGATED IN ORDER TO MINIMISE THE RISK OF ACCIDENTAL CONTACT




Chromic acid, nitric acid, hydroxyl containing compounds, ethylene glycol, perchloric acid, peroxides and permanganates


Conc. nitric acid and sulphuric acid mixtures


Chlorine, bromine, copper, silver, fluorine and mercury


Carbon dioxide, carbon tetrachloride, other chlorinated hydrocarbons.

IMPORTANT NOTE: DO NOT use water, foam or dry chemical on fires involving these metals, extinguish with dry sand

AMMONIA (anhyd.)

Mercury, chlorine, calcium hypochlorite, iodine, bromine and hydrogen fluoride


Acids, metal powders, flammable liquids, chlorates, nitrites, sulphur, finely divided organics or combustibles


Nitric acid, hydrogen peroxide


Ammonia, acetylene, butadiene, butane and other petroleum gases, sodium carbide, turpentine, benzene and finely divided metals



CARBON (activated)

Calcium hypochlorite


Ammonium salts, acids, metal powders, sulphur, finely divided organics or combustibles


Acetic acid, naphthalene, camphor glycerol, turpentine, alcohol and other flammable liquids


Ammonia, acetylene, butabiene, butane and other petroleum gases, sodium carbide, turpentine, benzene and finely divided metals,


Ammonia, methane, phosphine and hydrogen sulfide


Acetylene, hydrogen peroxide




Hydrogen peroxide, nitric acid and any other oxidant


Nitric acid, alkalies


Ammonia aqueous or anhydrous


Copper. Chromium, iron, most metals and metal salts, any flammable liquid, combustible materials, aniline, nitromethane


Conc. Nitric acid, oxidising gases


Acetylene, ammonia (aqueous or anhyd.)


Acetylene, fulminic acid, ammonia


Acetic acid, acetone, alcohol, aniline, chromic acid, HCN, hydrogen sulphide, flammable liquids and nitratable substances


Inorganic bases peroxides and amines


Silver, mercury


Oils, grease, hydrogen, flammable liquids, solids or gases


Acetic anhydride, bismuth and its alloys, alcohol, paper, wood grease oils.


Acids (organic or mineral) NOTE: avoid friction when handling also store at low temperature


Air, oxygen


Acids, ammonium salts metal powders, sulphur finely divided organics and combustible materials


Glycerol, ethylene glycol, benzaldehyde, sulphuric acid


Acetylene, oxalic acid, tartaric acid, fulminic acid, ammonium compounds


Ammonium nitrate and other ammonium salts


ANY oxidisable substance, such as ethanol, methanol, glacial acetic acid, acetic anhydride benzaldehyde, glycerol, ethylene, ethyl acetate etc…


Chlorates, perchlorates, permanganates

Toxic chemical hazards

Listed below are some chemicals which, if they come into contact will produce a toxic hazard. NOTE: this list is not exhaustive and very much a partial list to act as a guide for common hazards. It is YOUR responsibility to ensure you understand and minimise the risk of the accidental production of toxic products.

The substances in the left hand column should be store and handled with care so that they cannot possibly accidentally contact the corresponding substance in the centre column, because otherwise toxic materials (in the right hand column) would be evolved.







































Validate   Link-check © Copyright & disclaimer Privacy & cookies Share
Back to top