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The aim of this review is to develop a list of health-based recommendations for workplace exposure standards (WES) in Australia.

Recommendations for changes to the WES will be based on an evaluation of available information from trusted domestic and international sources. Only publicly available information will be used.

The review will result in recommendations for the workplace exposure standard values, notations and the list of chemicals. The recommendations and supporting information will be published in individual evaluation reports for each chemical.

The evaluations of individual chemicals that commenced in 2018 will continue throughout 2019 and 2020 and includes an independent peer review process.

Review of the workplace exposure standards timeline

PLEASE NOTE: In March 2020, Safe Work Australia has paused the release and public consultation for the WES review until further notice. More information about the public comment process.  


The limits to which workers can be exposed to hazardous airborne chemicals are published in the Workplace exposure standards for airborne contaminants (WES list).

The values published in this list are the airborne concentrations of a chemical that are not expected to cause adverse effects on the health of an exposed worker.

WES values are generally based on the adverse effect that occurs at the lowest airborne concentration of the chemical, or the ‘critical effect’.

There are three WES parameters under the model WHS laws:

  • if the critical effect is a chronic or sub-chronic effect:
    • eight-hour time-weighted average (TWA), and
  • if the critical effect is a short term or acute effect:
    • short term exposure limit (STEL), or
    • peak limitation.

Review methodology

The methodology to update the workplace exposure standards addresses selecting trusted sources of information, the composition of the WES list and how to come to a recommendation for a specific chemical.

Criteria for the selection of trusted sources

A workplace exposure standard recommendation will be determined by evaluating:

  • primary sources of data that will form the basis of decision-making for recommending a workplace exposure standard for a hazardous chemical, and
  • secondary sources of data that will be used where there are significant data gaps or in a weight of evidence approach where there is uncertainty arising from primary sources.

Trusted sources

Primary sources

The following bodies have met the criteria for trusted primary sources of data:

Secondary sources

The following bodies have met the criteria for trusted secondary sources of data:

Sources for notation recommendations

Advisory notations accompanying the workplace exposure standards include:

  • carcinogens (Carc. 1A, Carc. 1B, Carc. 2)
  • sensitisers (Sen), and
  • chemicals where significant absorption and toxicity may occur via the dermal route (Sk).

Under the model work health and safety (WHS) laws, the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is used for classifying hazardous chemicals.

The following bodies will be used to inform carcinogenicity and sensitiser notations for the workplace exposure standards in this review:

Information available in the primary and secondary sources can also inform whether a classification or notation may be required.

Criteria for the selection of hazardous chemicals to be added to or removed from the WES list

Criteria for identifying chemicals to be added or removed from the WES list have been developed to ensure it is reflective of contemporary Australian workplaces.

The chemicals identified will be available for public consultation through the regulation impact analysis process and considered by Safe Work Australia Members.

Chemicals that will be included in the review of the workplace exposure standards

The criteria for identifying chemicals to be considered for addition to the WES list have been applied to the trusted sources. The table below outlines the chemicals that meet these criteria.

These chemicals will also be evaluated as part of the review of the workplace exposure standards.

Chemical CAS No. Chemical CAS No.
1,2,3-Trimethylbenzene 526-73-8 Gallium arsenide 1303-00-0
1,2,4-Trimethylbenzene 95-63-6 γ-Butyrolactone 96-48-0
1,3,5-Trimethylbenzene 108-67-8 Glyoxal 107-22-2
1,3-Dioxolane 646-06-0 Hard metals (containing cobalt
and tungsten carbide)
7440-48-4; 12070-12-1
1,4-Dichloro-2-butene 764-41-0 Hexachlorobenzene 118-74-1
1-Bromopropane 106-94-5 Hexahydrophthalic anhydride 85-42-7
1H-Benzotriazole 95-14-7 Hexamethyl phosphoramide 680-31-9
2,4,5-Trimethylaniline 137-17-7 Hydroxyacetic acid butyl ester 7397-62-8
2,4-Pentanedione 123-54-6 Isopentane (2-methyl butane) 78-78-4
2-Ethylhexanoic acid 149-57-5 Man-made mineral fibres (fibrous dust)  
2-Ethylhexanol 104-76-7 Ethylene thiourea 96-45-7
2-Hydroxypropyl acrylate 25584-83-2 Flour Dust (cereal)  
2-Methylbutyl acetate 624-41-9 m-Cresol 108-39-4
3,3'-Dichlorobenzidine 91-94-1 Methyl Vinyl Ketone 78-94-4
4-Vinyl Cyclohexene 100-40-3 Natural Rubber Latex 9006-04-6
5-Nitro-o-toluidine 99-55-8 Neopentane
Benzidine 92-87-5 Nickel, insoluble  
Benzoyl chloride 98-88-4 N-Nitrosodimethylamine 62-75-9
Bisphenol A diglycidyl ether 1675-54-3 N-Phenyl-2-naphthylamine 135-88-6
Bisphenol-A 80-05-7 N-Vinyl-2-pyrrolidone 88-12-0
But-2-yne-1,4-diol 110-65-6 o-Anisidine 90-04-0
Chloromethyl methyl ether 107-30-2 o-Cresol 95-48-7
Chrysene 218-01-9 o-Tolidine 119-93-7
Cyanide salts   p-Cresol 106-44-5
Diacetyl 431-03-8 Peracetic acid 79-21-0
1,2-Dibromo ethane 106-93-4 2,3-Pentanedione
(Acetyl propionyl)
Dichloroacetic acid 79-43-6 Perfluorooctanoic acid (PFOA)
and its inorganic salts
Diesel engine emissions   Phenyl isocyanate 103-71-9
Diethyl sulfate 64-67-5 Piperazine and salts 110-85-0
Diethylene glycol monobutyl ether 112-34-5 Polyvinyl chloride 9002-86-2
Diglycidyl resorcinol ether 101-90-6 Polycyclic aromatic hydrocarbon (PAH)
mixture when containing benzo[a]pyrene
Dimethyl carbomoyl chloride 79-44-7 Propane sultone 1120-71-4
Dimethyl sulfide 75-18-3 Terephthalic Acid 100-21-0
Dimethylsulfamoyl chloride 13360-57-1 Tetrafluoroethylene 116-14-3
DMA 87-62-7 Toluene-2,4-diisocyanate 91-08-7
EDTA 60-00-4 Urethane 51-79-6
Ethyl Cyanoacrylate 7085-85-0 Vinylidene Fluoride 75-38-7
Ethylene 74-85-1 White spirit Type 3 64742-48-9

Based on the criteria, the chemicals below have also been identified as potential candidates to be removed from the WES list.

Chemical CAS No. Chemical CAS No.
1-Chloro-1-nitropropane 600-25-9 Methyl demeton 8022-00-2
ANTU 86-88-4 Nitrapyrin 1929-82-4
Bismuth telluride 1304-82-1 Nitrogen trifluoride 7783-54-2
Bismuth telluride, Se-doped 1304-82-1 n-Propyl nitrate 627-13-4
Bromine pentafluoride 7789-30-2 o-Chlorobenzylidene malononitrile 2698-41-1
Carbonyl fluoride 353-50-4 o-Chlorostyrene 2039-87-4
Chlorinated diphenyl oxide 31242-93-0 Oxygen difluoride 7783-41-7
Chlorine trifluoride 7790-91-2 Pentachloronaphthalene 1321-64-8
Chlorodiphenyl 42% chlorine (PCBs) 53469-21-9 Perchloromethyl mercaptan 594-42-3
Chlorodiphenyl 54% chlorine (PCBs) 11097-69-1 Perchloryl fluoride 7616-94-6
Crufomate 299-86-5 Phenylphosphine 638-21-1
Decaborane 17702-41-9 sec-Butyl acetate 105-46-4
Demeton 8065-48-3 Selenium hexafluoride (as Se) 7783-79-1
Diborane 19287-45-7 Sesone 136-78-7
Dioxathion 78-34-2 Stibine 7803-52-3
Emery (dust) 1302-74-5 Sulfotep 3689-24-5
EPN 2104-64-5 Sulfur pentafluoride 5714-22-7
Ferrovanadium dust 12604-58-9 Sulfuryl fluoride 2699-79-8
Fonofos 944-22-9 TEPP (tetraethyl pyrophosphate) 107-49-3
Germanium tetrahydride 7782-65-2 Tetrachloronaphthalene 1335-88-2
Hafnium 7440-58-6 Tetranitromethane 509-14-8
Hexachloronaphthalene 1335-87-1 Trichloronaphthalene 1321-65-9
Hexafluoroacetone 684-16-2 Yttrium, metal & compounds 7440-65-5
Hydrogen selenide 7783-07-5    

To date, there has been no decision to remove any chemicals from the WES list. Feedback on the list of chemicals above will be sought through the consultation RIS. Following consultation, the final composition of the WES list will be published. 

Recommending health-based workplace exposure standards and notations

Recommendations for workplace exposure standards will be made by following a consistent process of decision-making, and evaluating the information from the primary data sources (with supporting information from secondary sources where appropriate). Recommendations will also be made for values and notations for carcinogenicity, sensitisation of the skin or respiratory tract, and a skin notation where there is a risk of the chemical being absorbed through the skin.

This process may result in a recommendation to:

  • keep the existing WES value or notation
  • amend the WES value or notation, or
  • to withdraw the existing values or notations.

In some cases, there may not be enough data available for a recommendation or there may be uncertainty about the data. In these cases, an interim WES value may be recommended, accompanied with either:

  • a recommendation for a further assessment of the data for the chemical, or
  • a recommendation for a priority evaluation of the data for the chemical in the next scheduled review of the workplace exposure standards.

Each evaluation will be peer reviewed by an independent expert.

Once the evaluations and peer review is complete, individual chemical evaluation reports will be available on our website.

Criteria for a skin notation

 Some of the characteristics of the chemicals on the WES list pose a risk of being absorbed through the skin. The WES list assigned a ‘Sk’ notation for these chemicals to alert PCBUs to this risk.

Criteria have been developed to ensure the notation is consistently applied based on the evidence available from the trusted sources.

Non-threshold based genotoxic carcinogens

Some of the characteristics of chemicals on the WES list mean that there is no level of exposure without a risk to health.

An approach has been developed to identify these chemicals and calculate a level at which the risk is considered ‘minimal’.

Immediately Dangerous to Life or Health

An additional advisory notation, an Immediately Dangerous to Life or Health (IDLH) parameter, will be provided for some chemicals on the WES list.

This parameter was developed by the US National Institute for Occupational Safety and Health (NIOSH) to represent an airborne concentration of a chemical capable of:

  • causing death, or immediate or delayed permanent adverse health effects to a worker, or
  • impeding their escape from such an environment.

An IDLH is not considered an exposure standard; it is a concentration that may cause harm, rather than a concentration at which no adverse effects are expected.

However, an IDLH provides PCBUs and workers additional safety information for specific situations, such as working in confined spaces, industrial accidents (including chemical spills or explosions) or other uncontrolled-releases. These parameters may help guide accident prevention and emergency response planning in the workplace.

Contribute to the review

To stay up-to-date with the review into WES, or take part in consultation opportunities, subscribe to the chemical exposure standards mailing list.

If you have any further questions about workplace exposure standards, email WES@swa.gov.au.

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