Hazardous Substances (Chemicals)

Use of chemicals is widespread in workplaces, and many of these chemicals are hazardous to the health of workers. Further, some years ago the National Health and Safety Commission (more recently known as the Australian Safety and Compensation Commission - the ASCC) estimated that about 2,300 workers die each year as a result of exposure to hazardous substances. Hazardous substances are found in almost all workplaces.

Action plan for health and safety representatives

As with all workplace hazards, ionizing radiation should be dealt with in this way:

  1. Identification of the hazard
  2. Assessment of the risk. 
  3. Elimination or reduction of the risk
  4. Review and evaluation of any control strategies.

Hazardous substances should be eliminated from the workplace if possible. This will eliminate the risk. If this is not possible, then the preferred order of hazard control must be followed, as prescribed in the various parts of Chapter 4 (Hazardous Substances and Materials) of the 2017 OHS Regulations, and described in the Flow Chart (below). As the health and safety representative, you should:

  • Keep the workforce informed at all times. Make sure your DWG knows about the regulations and knows to notify you if any new substances are brought into the workplace, or if they suffer any effects which may be related to use of chemicals.

  • Insist that management has a system in place to implement the requirements of Chapter 4 of the Occupational Health and Safety Regulations (2017), and that you and other reps are consulted and involved at every stage.

  • Check that there is an up to date copy of the relevant Safety Data Sheet (or Material Safety Data Sheet) for all substances at the workplace. Check these: if you have any queries on specific substances, contact your union for advice.

  • Ensure that controls are implemented for any substances which have been identified as hazardous. These should be according to the preferred order as required under the regulations.

  • Check whether there are any hazardous substances requiring atmospheric monitoring or health surveillance are in use in your workplace. If so, check whether management has complied with the requirements of the regulations, hold meetings with your members and contact the union.

  • Check what the purchasing policy of the company is - prior to any new substance coming into the workplace, the SDS should be checked and any OHS reps consulted. Raise this at the OHS Committee for review if necessary.

Legal Standards

In Victoria, chemicals defined as hazardous are regulated under Chapter 4 (Hazardous Substances) of the Occupational Health and Safety Regulations, 2017.

The regulations set out specific duties for the employer including:

  • Establishing registers of hazardous substances and materials in the workplace
  • Labelling, etc
  • Carrying out hazard identification, and controlling the risk arising from the identified substances
  • Providing information and training to workers
  • Keeping and maintaining records
  • Atmospheric monitoring
  • Health monitoring

Employers still have duties with relations to all other chemicals, not only those classified as "hazardous" under the general duties in the Victorian Occupational Health and Safety Act (2004). Employers have a general duty under Section 21 to provide and maintain for employees, as far as practicable, a working environment that is safe and without risks to health. In particular, the employer must:

"...make arrangements for ensuring so far as is reasonably practicable safety and absence of risks to health in connection with the use, handling, storage and transport of ...substances". (Section 21(2)(b))

General introduction to the legislation covering Hazardous Substances.

Exposure standards

There are legal limits to the concentration of some of the chemical fumes that workers may be exposed to.

About 700 of the most common hazardous substances have exposure standards. These standards are controversial for a number of reasons:

  • These are maximum levels and have been established as time weighted averages over 8 hours, 5 days per week. Many workers now work longer hours. If you have a 12-hour shift at your workplace, the employer should contact the supplier to estimate an appropriate exposure standard. However, this has never been "scientifically" calculated.

  • The levels have been established based on the assumption that they are "safe" for most people - they do not take into account individual differences.

  • Often workers are exposed to several substances at the same time.

  • There are up to 40,000 chemicals used in Australian workplaces. 

Exposure Standards are not necessarily adequate and should be regarded by unions as maximum exposure levels only, not "safe" levels. Exposure should be reduced as much as possible.

(See Exposure Standards for Chemicals for more information)


Exposure levels can be indicated by use of monitoring equipment to measure the concentration of contaminants in the air within the workers' breathing zone. (This is important because inhalation of chemical fumes, vapours, gases, etc. is the most common route of entry - however, this can't measure what might be absorbed through the skin.)

Detector tubes are commonly used for spot-checking or eight-hour exposure measurements.

Such concentrations are measured either as parts per million or air (ppm) or milligrams per cubic metre of air (mg/m3).

Information on Hazardous Substances

What are the health effects of exposure to Hazardous Substances?

Exposure to chemicals may result in a wide range of health effects and any part of the body may be affected - at the sites where substances enter the body; in the bloodstream or circulatory system by which chemicals may be transported through the body; in the excretory organs and mechanisms which attempt to remove them from the body; in the central nervous system (including the brain), and in any other organ or tissue.

Acute effects

  • Fairly immediate response to exposure, eg: rash, coughing spell, watering eyes, unconsciousness, death.

Chronic effects

  • Not always immediately obvious.
  • May involve a gradual onset of symptoms.
  • May not be experienced for a long time after exposure, eg cancers.
  • Usually irreversible.


  • Exposure is often to more than one chemical or in conjunction with other hazards like heat or noise.
  • The resultant effects of such combined exposure may be greater than a simple addition of effects of exposures to individual hazards.

Mechanism of Effects

The ways in which chemicals may affect the body are as follows:

Poisoning (Toxic)

  • Causing injury to biological tissue; the substance enters the body and causes a short-term effect (eg unconsciousness) or a long-term effect (eg liver disease, cancer).


  • Burning of the skin or lungs;
  • Blindness, when substances are splashed into the eye.


  • Inflammation of the skin (dermatitis);
  • Inflammation of the respiratory tract (bronchitis).


  • Allergic reaction in the lungs (asthma)
  • Allergic reaction on the skin (contact dermatitis).

Severe Toxic Effects

A chemical may be MUTAGENIC: exposure to it may produce changes in the genetic apparatus of the cell. In normal body cells this may result in disease. In germ (reproductive cells - sperm or ova) this may result in sterility or hereditary effects for subsequent generations.

A chemical may be CARCINOGENIC: exposure may result in the explosive growth of cells forming a tumour, which may be benign (a localised growth) or malignant (spreading). Both types of tumour may be fatal, depending on location.

A chemical may be TERATOGENIC: it may enter a pregnant woman's bloodstream and cross the placenta barrier to affect the developing foetus. This may result in:

  • Spontaneous abortion (miscarriage)
  • Reduced birth weight
  • Congenital abnormalities (damage to organs or limbs)
  • Brain damage
  • Cell damage which later results in cancer

The actual health effect or extent of health effects of exposure to any chemical depends on four factors:

  1. Its form
  2. Its physical properties
  3. Its route of entry into the body
  4. How the body deals with it once it has entered the body

1. Form

The form of a substance influences how it can get into the body and what damage it can cause.

Solids are least likely to cause harm as they are unlikely to enter the body accidentally except as splinters or high velocity projectile, eg paint via compressed air. Solids can contaminate skin or food, however. The main danger is that they can change form while being worked, eg turning wood results in formation of dusts; welding rods give off fumes and vapors; burning polyurethane foam gives off deadly gases - all of which may be inhaled.

Dusts are tiny airborne particles of solid matter which may be inhaled. Larger particles are usually trapped by the hairs and mucous in the nose and windpipe where they can be expelled by coughing, blowing the nose, etc. This can result in damage - such as cancer of the nose. Smaller particles may be breathed in deeply and can damage the lungs or enter other parts of the body through the bloodstream. Some dust clouds may also explode.

Liquids may damage the skin or pass through the skin into the bloodstream. Many give off vapors, which may be inhaled. Many substances are liquids at normal temperature (eg solvents).

Vapors and Mists are tiny droplets of liquid suspended in the air due to evaporation. Vapors may irritate the eyes or skin and may be inhaled. Some vapors are flammable or explosive.

Gases are the most likely to be inhaled. Some substances are gases at normal temperature. Others (solids or liquids) form gases when heated. Some may have immediate irritant or corrosive effects. Others can affect internal organs. Some gases are flammable or explosive.

2. Physical Properties

Knowledge of the physical properties of a chemical can give an indication of the nature or extent of potential health effects given certain environmental conditions, and enables decisions to be made in respect of correct use and storage procedures.

  • Boiling Point - some liquids can give off gases and vapours even when below boiling point.
  • Melting Point - the temperature at which a solid turns to liquid.
  • Evaporation Rate - the rate at which a liquid evaporates, that is, changes to gas (measures "volatility"). Highly volatile liquids are a greater hazard in terms of potential inhalation of vapours, as they evaporate more quickly.
  • Vapour Pressure - high vapour pressure usually means more vapour will be given off.
  • Vapour Density - how heavy the vapour is compared to air.
  • Flash Point - it the temperature at which a flammable liquid produces enough vapours to be ignited by a spark (eg petrol has a flash point at -38 degrees Celsius). The Standards Association of Australia defines a liquid as flammable if it has a flash point of less than 61 degrees Celsius. (Flammable gases and solids do not have a flash point, as they require no preheating to catch fire, only a source of ignition.) Many solids require heating before they ignite, eg charcoal.
  • IGNITION TEMPERATURE - is the temperature at which flammable liquids, solids or gases spontaneously burst.
  • FLAMMABLE RANGE - the range of concentration of vapour in the air at which vapour will burn (eg petrol: 1.4 - 7.6%; acetylene: 2.5 - 81%).

(The above information should be included in material safety data sheets for each chemical product: More information on SDSs.)

3. Route of Entry

The route of entry of a chemical into the body determines both the site of physical damage and the extent of the potential hazard. There are three main routes of entry:

i) Inhalation

Breathing in dusts, gases and vapours is the most common route of entry. Inhalation may result in:

  • Irritation of the respiratory tract (bronchitis) or a sensitising effect on the lungs (asthma);
  • The substance remaining in the lungs causing scarring, cancers;
  • The substance being absorbed into the bloodstream and affecting other organs.

ii) Absorption

Absorption through the skin (or eye) is another route of entry for toxic substances. Effects include:

  • Burning of the skin/eye;
  • Irritation of the skin (dermatitis); sensitising effects (contact dermatitis); skin cancer;
  • The substance penetrating the skin/eye and entering the bloodstream to affect other organs. The size of molecules of the substance determines level of absorption.

iii) Ingestion

Swallowing substances is the least common route of entry for toxic substances. However, there are ways that toxic substances may be ingested, pass through the digestive system, and affect the gastro-intestinal organs of the body:

  • Inhaled compounds which are trapped in the mucous of the respiratory tract may be swallowed;
  • Eating or drinking foods contaminated by toxic substances;
  • Smoking cigarettes or eating with contaminated hands.

4. How the body deals with toxic substances

How the body deals with a chemical once it enters the body also determines the site of physical damage and the extent of the potential hazard. The body deals with chemicals in one of three ways:

i) Excreted

A major exit for toxic substances in the body is via the kidneys and bladder. The kidneys filter the blood, removing what is not needed and stores the resultant urine in the bladder. The kidneys and bladder may be damaged in the process. Another significant exit route is the respiratory tract and lungs, ie being breathed out. Others include sweat glands, nails and hair (as in the case of mercury and other metals).

ii) Stored

A substance may be stored in an organ or tissue having constant exchange with the bloodstream. This can result in damage, eg lead in bones.

Other substances are fat-soluble and are stored in our fatty tissues (eg some pesticides).

iii) Metabolised

A substance may be converted into other substances by reaction with enzymes. These substances may be harmful or harmless. Eg: the liver "detoxifying" alcohol. The process itself, however, may cause damage to the liver such as hepatitis and cirrhosis. The liver may also convert substances into cancer-causing agents.

See Also:
  • The Regulations

  • Other information on this site in the ToolKit Section: Checklists and Policies. 

  • Information on Dangerous Goods

  • Resource Manual for Health and Safety Representatives, ACTU Booklet 'Controlling Hazardous Substances' 
  • Other union publications

  • Chemicals management in workplaces  - a paper by the late Professor Chris Winder from the School of Safety Science, University of New South Wales, which provides practical advice to OHS reps on chemical management in the workplace and how to go about it.

  • A Step by Step Guide for Managing Chemicals in the Workplace [pdf] - A Victorian WorkSafe guide to assist employers to manage chemicals safely, and to comply with the relevant aspects of the Victorian Occupational Health and Safety (Hazardous Substances) Regulations 2017 and the Dangerous Goods (Storage and Handling) Regulations 2012. 

  • The WHS model regulations have a chapter on Hazardous Chemicals and relevant New Model codes on Hazardous Chemicals from Safe Work Australia 
    • Managing Risks of Hazardous Chemicals in the Workplace
    • Labelling of Workplace Hazardous Chemicals
    • Preparation of Safety Data Sheets for Hazardous Chemical

  • NIOSH, the National Institute for Occupational Safety and Health in the US, has many chemical related topics on its website 

  • UNIFOR (a large Canadian manufacturing union):  Prevent Cancer Campaign with resources including a Cancer Campaign book and a Personal Chemical Exposure Journal.

  • Other websites - see this page on this site

Last updated December 2020