Skin contact is often the unrecognized route of entry into the body. While it provides reasonable protection against particulate matter, it provides very little protection of entry for substances such as solvents.
Inhalation – breathing in
Consideration must be given to the body’s natural defence mechanism against inhaled particles. The ciliary escalator carries foreign bodies up the respiratory tract where they are either spat out or swallowed.
Ingestion – eating and drinking
An estimated 50 per cent of the particles deposited in the upper respira-tory tract and 12.5 per cent from the lower passages are eventually swal-lowed.
Injection – puncturing skin; for example, needle
Needle injuries are common for health care workers, police and other public workers.
ACTIVITY
What is the most common form of entry for hazardous substances in your workplace, and why?
Biological agents
Biological agents are micro-organisms (fungi, bacteria and viruses) which may cause infection, allergy or toxicity, or otherwise create a hazard to human health.
ACTIVITY
List any biological hazards that you may be at risk from, due to the nature of your work.
Identify examples of biological agents:
■ Fungi.
■ Bacteria .
■ Virus.
Factors to consider when assessing hazardous agents:
■ Potential route(s) of entry – how the substances can enter the body (e.g. inhalation, skin absorption).
■ Effects they may cause (e.g. dermatitis).
■ Physical properties of hazardous agents.
■ Quantities of hazardous agents used.
■ Ways in which the solvent is applied (by hand/brush/spraying?).
■ Frequency and duration of exposure to hazardous agents.
■ Work methods employed.
■ Who is being affected – the number of individuals exposed, their health status, pregnancy, etc.
■ Information – manufacturers’ material safety data sheets, guidance documents, etc.
■ Potential additive/synergistic effects from other hazardous agents.
■ Existing control measures in terms of their nature and adequacy.
■ Identify the best form of atmospheric monitoring (AM) or biological monitoring (BM) for the hazardous agent.
Atmospheric monitoring (AM) involves the monitoring of airborne workplace contaminants through personal monitoring or, on occasion, through static monitoring. AM has limitations in that it excludes skin and ingestion as routes of absorption. AM may take a variety of forms with a number of available techniques; it is generally non-invasive.
Biological monitoring (BM) involves the measurement of indicators of the uptake of toxic substances in the body, such as in blood, urine or exhaled breath, in order to prevent health impairment. BM includes
non-occupational exposure and takes into account individual dose and metabolism. BM is useful where there is a high dependency on personal protective equipment (PPE).
After gathering data about the hazardous substance (i.e. from the safety data sheets) a risk assessment for hazardous substances needs to be undertaken. This will include completing a pro-forma assessment with headings, such as:
■ Date or internal company reference.
■ Company information about product and/or trade name.
■ Properties (i.e. vapour pressure, dustiness, etc.).
■ Composition (i.e. proportion of the different components).
■ Hazard and/or risk classifi cation.
■ Any short- or long-term exposure limits (for the country in which it is to be used).
■ Description of the task(s).
■ Details of the exposure profi le.
■ Details of the number of people exposed.
■ Outline of the control measures being used.
■ Details of the handling and storage facilities and processes.
■ Details of the disposal of excess and waste material.
■ Precautions and emergency procedures.
■ Assessment of residual risk after control – high/medium/low.
■ Results of airborne monitoring.
■ Any further action(s) required.
■ Review date (one year or less).
Once information has been gathered, control measures can be designed and implemented. These will be included in the risk assessment and if further action is needed this too must be recorded.
Hierarchy of control for hazardous substances
The following outlines the hierarchy of control for using substances hazardous to health. The following questions need to be addressed:
Eliminate
Can the hazardous substance be eliminated?
For example:
■ Pigeon droppings are a hazardous substance – if you stop pigeons roosting (e.g. by using netting), you will prevent the buildup of drop-pings, meaning that people will not be exposed to them or need to use potentially hazardous products when cleaning up the droppings.
■ Lead has been removed from petrol in many countries due to its haz-ardous properties.
■ Use water-based paints so that you don’t need to use white spirit or thinners.
Substitute
Can a less hazardous substance be substituted for a particular task?
For example:
■ Put down an insecticide gel rather than using powder or spray, which may drift in the air and be inhaled or ingested by young children, who may mistake it for sherbet when it is used in nurseries, etc.
■ Use a lower concentration of the hazardous substance – such as Milton fl uid to disinfect surfaces rather than bleach (same chemical, just a lower concentration).
■ Use chlorine tablets to disinfect swimming pools rather than powder, reducing the risk of inhalation of dust when handling the chemical.
■ Use water-based paints rather than solvent-based paints (with the added benefi t that thinners are not needed to clean brushes).
Technical engineering controls
Can the development of technical engineering controls reduce the risk?
For example:
■ Capturing emissions by using dust bags on sanders and planers or HEPA fi lters on vacuum cleaners (remember to also consider how you will handle and dispose of collected emissions safely).
■ Distance yourself from the substance; for example, by using a long-handled wiping tool in printing rather than applying the substance to a rag in your hand.
■ Enclosing the substance by putting lids back on containers when not in use.
■ Enclosing the work process by working with the substance in a fume cupboard or glove box.
■ Extracting emissions using Local Exhaust Ventilation (LEV), such as an extractor hood on a circular saw to remove sawdust as it is produced.
■ Where release cannot be contained (e.g. when painting), use general ventilation by opening doors and windows (non-toxic emissions only).
Procedural controls
Is it possible to change the work process or system to emit less of the substance or limit associated dangers?
For example:
■ Brushing on paint rather than spraying it.
■ Using water to suppress dust.
■ Closing windows and/or doors to prevent air currents from blowing substances around.
■ Storing less of the substance on the premises.
■ Storing and using substances in different locations to prevent them from mixing with substances that could react dangerously if mixed together; for example, before using bleach to clean a toilet, fl ush the toilet to remove any other substance that may be in the bowl.
Behavioural controls
Workers must take responsibility for themselves.
For example:
■ Following the information, instruction and training provided.
■ Using all protective measures including wearing personal protective equipment (PPE).
PPE should always be the last resort as it only protects the person wear-ing it, and it is the most likely control to fail in its protection.
Main reasons for the failure of PPE include:
■ Can be heavy or cumbersome, restricting movement and causing wearer to become hot.
■ Inadequate fi t for wearer.
■ Incompatible with other PPE or personal items (e.g. goggles worn by workers with glasses).
■ Interferes with other senses (e.g. sense of smell when wearing a mask).
■ Must be used correctly – may require special training.
■ Pressure to get the work done – it may be perceived that it takes ‘too long’ to put on all PPE needed.
■ Requires maintenance and storage.
Hazardous substance risk assessment
Factors to consider when carrying out a hazardous substance risk assess-ment include looking at the substance, individual, task and environassess-ment (SITE) and asking the following questions:
Substance ■ Are there any exposure limits?
■ Could the substance be mixed (intentionally/accidentally) with another, which could be dangerous?
■ How often may people be exposed?
■ How will it get into the body?
■ Might the substance produce dangerous fumes or be a fi re risk?
■ In what form is the substance (solid, liquid, airborne)? Would this lead to signifi cant exposure?
■ What harm could it do to the body?
■ What is the chance of exposure? This may be affected by the training and information people have and how reliable and suitable the control measures are.
Individual ■ Are there any people who would be particularly vulnerable?
■ Are users capable of using the substance safely?
■ Who will be using/be exposed to the substance?
Task ■ How will the substance be used or produced?
■ What other hazards may be involved?
■ What will the user do next?
■ Will a substance be used in line with the manufacturer’s instructions?
Environment ■ Is there anything in the environment that could be incompatible with the substance (e.g. naked fl ames in the presence of fl ammable substances or other substances that could chemically react with it)?
■ Where is the substance going to be used/produced and who might it affect?
ACTIVITY
Review a COSHH assessment from your workplace using the above questions.