Exposure values
| CAS number | 552-30-7 |
|---|---|
| Current WES (to 30 Nov 2026) | 0.005 ppm (0.039 mg/m³) TWA [Sen] |
| WEL (from 1 Dec 2026) | 0.00006 ppm (0.0005 mg/m³) TWA; 0.00002 ppm (0.002 mg/m³) peak limitation [DSEN, RSEN, Sk] |
| Change | Limit reduced (stricter) |
| Notations, WES (to 30 Nov 2026) | Sen: sensitiser (WES list) |
| Notations, WEL (from 1 Dec 2026) | DSEN: dermal (skin) sensitiser; RSEN: respiratory sensitiser; Sk: skin absorption may be a significant source of exposure |
| Notation change | added DSEN, RSEN, Sk; removed Sen |
| Other names | Benzene-1,2,4-tricarboxylic acid-1,2-anhydride; 5-Isobenzofurancarbo xylic acid, 1,3-dihydro-1,3-dioxo- |
TWA: 8-hour time-weighted average. STEL: 15-minute short-term exposure limit. ppm values apply to vapours and gases; mg/m³ to all forms.
What to do in your register
- Record the new, lower WEL against this substance, to apply from 1 December 2026. The WES value applies until 30 November 2026.
- Compare any past air monitoring results with the new WEL, not the old WES. A result that was under the WES can be over the WEL.
- If exposure could be near the new limit, review your controls and think about whether air monitoring is needed before 1 December 2026.
- Update the notations: add DSEN, RSEN, Sk; remove Sen.
- Match your register row by CAS number (552-30-7) from section 3 of the safety data sheet (SDS), not by trade name.
Information only, not WHS or occupational hygiene advice. If you need to know actual exposures, talk to an occupational hygienist.
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Source
Values for this substance: Safe Work Australia, Changes to Workplace Exposure Limits, effective from 1 December 2026 (comparison table last updated 29 May 2025). Full lists: Safe Work Australia WEL list, WES list and WES-to-WEL comparison table.
© Commonwealth of Australia (Safe Work Australia), licensed under CC BY 4.0. Changes: values machine-read from SWA's files, reformatted and combined into one WES-to-WEL comparison per substance. This site isn't affiliated with or endorsed by Safe Work Australia.
Dataset swa-2026-10-11, every value cross-checked against the PDF lists. Page generated 2026-10-12.