Under the WHS Regulations, a substance is a hazardous chemical if it meets criteria under the Globally Harmonised System of Classification and Labelling of Chemicals (GHS classification system) Edition 7.

Regulation 5 of the WHS Regulations defines a hazardous chemical as a substance, mixture or article that satisfies the criteria for any 1 or more hazard classes in the GHS (including a classification referred to in Schedule 6), unless the only hazard class or classes for which the substance, mixture or article satisfies the criteria are any 1 or more of the following —

• acute toxicity — oral — category 5;
• acute toxicity — dermal — category 5;
• acute toxicity — inhalation — category 5;
• skin corrosion/irritation — category 3;
• aspiration hazard — category 2;
• flammable gas — category 2;
• acute hazard to the aquatic environment — category 1, 2 or 3;
• chronic hazard to the aquatic environment — category 1, 2, 3 or 4;
• hazardous to the ozone layer;       

The person manufacturing or importing the chemical is responsible for conducting the hazard classification.

The label and safety data sheet of the substance must indicate if it is a hazardous chemical.

PCBUs have a primary duty of care to eliminate or reduce risks to workers and others, so far as reasonably practicable.

A risk assessment should be undertaken to determine what hazardous chemicals are allowed on site, and the consequences of exposure or hazardous reactions that may impact on the health or safety of workers. In addition, a PCBU needs to establish and maintain a hazardous chemicals register, and, where required, conduct air monitoring and implement a health monitoring program for workers. More reliable controls must be implemented where practicable, based on the hierarchy of controls.

Workers and health and safety representatives, where present, must be consulted on safety and health matters.

Code of practice – How to manage work health and safety risks

Code of practice – Managing risks of hazardous chemicals in the workplace

Code of practice – Mine safety management system

Code of practice – Work health and safety consultation, cooperation and coordination

Part of the risk assessment before introducing a hazardous chemical to a workplace is to consider the following questions.

• Is the substance is absolutely required for the purpose?
• Is there is a safer alternative?
• How can the chemical and its waste be disposed of with no harmful effects?
• What quantity is required to be kept and how can it be stored safely?
• Is a licence or permit is required and are there any legislated safety requirements for the substance (e.g. hydrofluoric acid, mercury)?

It is important to consider that some hazardous chemicals may be generated by work activities (e.g. silica dust, fibres, welding fumes, diesel exhaust) and these hazards must also be identified and controlled.

Manufacturers and importers must:

• determine whether substances they manufacture or import are hazardous chemicals; 
• ensure that as far as practicable the substance does not present a hazard when used as directed;
• conduct any necessary testing or analysis and make that information available to others in the supply or use chain if necessary for safety purposes;
• before the hazardous chemical is supplied to workplaces, prepare a safety data sheet (SDS) and ensure it is available;
• review and revise the SDS as often as necessary to keep it up to date, and at least every five years;
• provide the SDS to any person who may be exposed to the substance and requests a copy of the SDS; and
• correctly label hazardous chemicals  they supply.

A Safety Data Sheet (SDS) is a document that provides information about a hazardous chemical and how to safely use it at the workplace. It must be written in English and contain the information outlined in the Code of practice for the preparation of safety data sheets for hazardous chemicals.

Hazardous chemicals must be labelled in accordance with the requirements of the Code of practice – Labelling of workplace hazardous chemicals.

PCBUs must:

• consult with people who might be exposed to the hazardous chemical at the workplace about the intention to use the substance and the safest method of using it;
• obtain (from the supplier) a safety data sheet (SDS) before or on the first occasion a hazardous chemical is supplied to the workplace;
• keep a current hazardous chemicals  register of all hazardous chemicals  used at the workplace from time to time and ensure it is readily available;
• provide information and training to people likely to be exposed to a hazardous chemical at the workplace before they start work, including information and training on:
• the potential health risks and any toxic effects;
• the control measures and their correct use;
• correct care and use of PPE; and
• any need for, and details of, health monitoring.
• keep records of the information and training provided;
• reduce the risks to people at the workplace that could arise from exposure to a hazardous chemicals by means of preventing of exposure, or where this is not practicable, reducing exposure using controls other than personal protective clothing and equipment (PPE). Only use PPE where other controls are not practical or not sufficient;
• ensure no person is exposed at the workplace to a hazardous substance above its workplace exposure standard (WES), (also known as a workplace exposure limit (WEL));
• in certain situations, ensure there is health monitoring;
• for mine sites, implement a health management plan – see the Information Sheet – Overview of mine safety management system code of practice or the Code of practice – Mine safety management systems.

In many circumstances, a risk assessment will be the best way to determine the measures that should be implemented to control risks for hazardous chemicals in the workplace. It will help you to:

• identify which workers are at risk of exposure
• determine what sources and processes are causing that risk
• identify if and what kind of control measures should be implemented
• check the effectiveness of existing control measures.

Where the hazards and associated risks are well-known and have well established and accepted control measures, it may not be necessary to undertake a risk assessment, for example, where there are a small number of chemicals in a workplace and the hazards and risks are well understood. If after identifying a hazard you already know the risk and how to control it effectively, you may simply implement the controls.

Any competent person can do a hazardous chemicals risk assessment. Some straightforward assessments can be done in-house. Others may be more complex and you may need to engage someone with expertise such as an occupational hygienist. Consultants can be found online under ‘occupational health and safety’ or ‘occupational hygiene’. Some occupational hygienists are listed by the Australian Institute of Occupational Hygienists.

Guidance on conducting a risk assessment is provided in the Code of practice – Managing risks of hazardous chemicals in the workplace.

Regulation 49 of the WHS Regulations requires a PCBU to ensure that no person at the workplace is exposed to a hazardous chemical above its workplace exposure standard.

Workplace exposure standards represent airborne concentrations of substances in a person’s breathing zone, which should neither impair the health of nor cause undue discomfort to nearly all workers. Additionally, compliance with WES should guard against narcosis or irritation, which could cause accidents.

WES are published by Safe Work Australia.

Interpretation of airborne chemical concentrations can be complex and should be done by a competent person and with reference to guidance published by Safe Work Australia. 

The work health and safety laws currently uses the term ‘workplace exposure standards’ (WES). Types of WES include time weighted average (TWA) exposures, short term exposure limits (STEL) and peak exposure limits.

There has been a policy decision to rename workplace exposure standards to ‘workplace exposure limits (WEL’ in future. This is to make the point that the WES (or WEL in future) are set in law. However it will not change how WES/WEL are assessed or used.

Safe Work Australia has further guidance on WES.

Under the WHS Regulations, the PCBU must keep a current register of hazardous chemicals used at the workplace.

A hazardous chemicals register must contain:

• a list of all the hazardous chemicals used in the workplace; and
• the SDS for each hazardous chemical.

A hazardous chemicals register must be readily available to all workers and others who may be potentially exposed to the hazardous chemicals, including emergency services.

A register of hazardous may be provided electronically if all workers who may need to access the register have access to a computer or equivalent device and are trained on how to use the system. There should be a system in place to ensure the register will be readily available in the event of foreseeable incidents such as a power failure or network failure.  

Your risk assessment should help you to work out if you need to do air monitoring. Some indicators of a need for monitoring may include:

• frequent or long duration use of a chemical or process which generates hazardous vapour, dust, mist or fume; and
• efficiency of ventilation is not known or no mechanical ventilation; and/or
• people in the workplace are complaining of health concerns that may be due to the vapour, dust, mist or fume; and/or
• there is the potential for serious health effects if controls are inadequate; and/or
• it is a complex work environment and it is difficult to estimate exposure.

Some substances present a risk even at low levels and air monitoring should be conducted periodically to check that controls are working, for example respirable crystalline silica.

If you are unsure whether air monitoring is required, consult an occupational hygienist for advice.

Quantities requiring a cabinet (or a flammable liquid store) depend upon the type of workplace, the floor space and the nature of the flammable or combustible liquid. 

Your cabinet should be constructed in accordance with Australian Standard, AS 1940 The Storage and Handling of Flammable and Combustible Liquids. 

The bottom of the cabinet is designed to hold spills and should not be used for storage.

Use your cabinet only for flammable and combustible liquids – do not store other classes of dangerous goods in it, unless you have checked that they are compatible with the flammable and combustible liquids.

The self-closing mechanism of the doors should be in good working order. 

The cabinet should be marked with a Class 3 Flammable liquid label and the words ‘No Smoking, No Ignition Sources within 3m’ and the maximum storage quantity of the cabinet.

Containers in the cabinet must be closed.

Cabinet ventilation may be required for very volatile, toxic or corrosive substances. This can be determined by a risk assessment. If your cabinet smells, ensure it is clean and that all containers are clean and tightly closed. If cabinet ventilation is required, it must be to the outside of the building away from air intake points and the ventilation must not reduce the level of fire protection of the cabinet or create an ignition source. (Note: opening cabinet ventilation outlets without venting to the outside is not recommended, as it could allow flammable vapours into the work environment and reduce the fire protection of the cabinet).

The cabinet should be located:

• so as not to impede emergency exits; and ​
• 3m or more from ignition sources other than ceiling lights.

For further information refer to Australian Standard, AS 1940 The Storage and Handling of Flammable and Combustible Liquids.

For large quantities of flammable liquids, refer to dangerous goods requirements.

Consider if the hazardous chemical is still required at the workplace or no longer used, as you may decide to dispose of it. If the product is retained, a recent SDS (no more than 5 years old) must be readily available where practicable at the workplace.

In the first instance an updated version should be requested from the supplier, manufacturer or importer. However, if the manufacturer has ceased trading, and an updated SDS is not available, the old SDS can be kept on the register with a note that it is the most recent. More recent information should be used to supplement it (to ensure for example that users are aware if the hazards have been reclassified). This could be a recent SDS from another supplier provided the formulation is the same (eg pure chemicals), or it could be a third party SDS (ie prepared by a consultant), or equivalent information.

Process plants and refineries

A wide range of hazardous chemicals is typically found in process plants and refineries, including:

• acids such as sulfuric acid, hydrochloric acid and nitric acid, which are frequently used to dissolve metals in ores
• caustic soda (sodium hydroxide), which can be used as a reagent to dissolve bauxite in alumina refineries, or to neutralise acid process streams and wastes
• sodium cyanide, which is used on most gold mines to help process the ore

Xanthates, used as a flotation chemical, solvents and compressed gases may also be found. Hazardous chemicals such as sulfur dioxide, hydrogen sulfide, carbon monoxide and oxides of nitrogen may be generated during the processing of mineral ores. Sodium cyanide must be strictly managed to minimise worker exposure through direct contact or from hydrogen cyanide gas.

Mine site laboratories commonly have the greatest variety of chemicals found on the mining operation, though typically in relatively small quantities. Acids used to digest materials generally represent the greatest risk, although all chemicals must be handled carefully.

Fire assay laboratories can use large quantities of lead reagents, while the sample preparation area will need to manage respirable crystalline silica dust, fibres generated while preparing samples, and fumes.

For security reasons, few people have access to gold rooms, but common hazardous chemicals found there are acids, cyanide and fluxes. Ammonia from electrowinning and lead, arsenic or mercury from smelting gravity gold may also need to be managed.

Mine site workshops typically include light and heavy vehicle, mechanical and electrical areas. Most oils, greases and other lubricants present a low hazard. However, cleaning solvents, spray painting chemicals and dusts generated during grinding and sand blasting need to be controlled.

Fumes generated from welding, cutting or vehicle exhausts can be a potential issue, particularly in enclosed areas.

• MSB No. 094: Use of contact cleaning agents - 113 Kb
• Mines Safety Bulletin No. 094: Use of contact cleaning agents (16 December 2010)

Many mines have reverse osmosis or other water treatment plants. Hazardous chemicals that need to be managed to minimise exposure include acids and chlorine.

One of the most common dusts encountered on mine sites is quartz (crystalline silica), which is a mineral found in many orebodies.

• Guidance about dust and other airborne contaminants

Several varieties of asbestiform minerals may be encountered during exploration and mining of iron ore, base metals and gold.

• Guidance about fibrous mineral hazards

Diesel emissions from equipment contain a number of toxic chemicals.

• Guidance about underground air quality and ventilation