Dichloroacetic acid did not have a workplace exposure standard. From 1 December 2026 it has a Workplace Exposure Limit of 2.5 mg/m³ (0.5 ppm), an 8-hour time-weighted average, once that limit is given effect in your jurisdiction. Safe Work Australia’s May 2025 changes list is the source. That row does not set a short-term exposure limit. Do not add one in toolbox talks or contractor packs.
Until 30 November 2026 the current exposure-standards list is still the airborne compliance reference. After that date, check your WHS regulator for commencement. A national policy PDF is not the local instrument.
The exposure is in the open minutes
On a pharma, fine-chemical or contract-manufacturing site, dichloroacetic acid often looks closed on the drawing: reactor, controlled feed, nobody “handles” it. Audits fail on the minutes that are not on the drawing. Someone opens a drum to charge. Someone takes a mid-batch sample. Someone drums an intermediate, breaks a line, or changes a filter.
A limit of 2.5 mg/m³ only does work if the register says dichloroacetic acid at those points. “Haloacetic acids,” “process acids,” or a trade blend that never names the substance is a naming gap, even when the batch sheet is tidy.
Vapour and aerosol show up on warm transfers and vacuum breaks. A closed process description does not cover those minutes.
Who is actually in the vapour
On a typical campaign the people worth mapping are not one job title:
- Charge and weigh: drum open, pump or pour into the charge vessel
- Sampling: reactor, receiver, day tank
- Drumming and packing: fill, bung, wipe
- Maintenance: filter, pump and valve work on the intermediate circuit
- Lab and kilo-lab: small volumes in rooms with weak extraction
- Spill response and damaged-package salvage during a campaign
Ask operations three things before you draw similar-exposure groups. How many minutes is dichloroacetic acid open to air on a real batch? Is charge under local exhaust, in a booth, or on an open pad? Does the person who samples share that exposure, or is it a different job?
Stock and dilute streams both need the chemical name. A visiting QA or a contractor on the campaign belongs on the same map.
A short charge is not the eight-hour limit
Clients sometimes treat a three-minute open charge as if it had already breached 0.5 ppm. The published comparator is the 8-hour average. The short task still matters: it is where irritation and poor capture show up, and it has to be folded into the shift average with the unsampled time stated. Skin and eyes can dominate even when the air result looks comfortable. Air monitoring does not close an acid-contact assessment.
What to put on the register and the permit
Name dichloroacetic acid on the hazardous-chemical register, including blends and intermediates. List the groups that can inhale vapour or aerosol: charge, sampling, drumming, maintenance, lab. Check that safety data sheets, placarding and emergency steps cover corrosivity and irritation as well as inhalation. Line-break permits should treat vapour during intermediate work as expected, not as a surprise. If you have any older air data, read it against 2.5 mg/m³ and 0.5 ppm rather than against “we never had a limit.”
If a contract manufacturer runs the campaign, the PCBU that engages them still needs the substance named and the exposure logic written down.
Plant changes that match this chemical
Closed transfer (pipe or tote) and smaller-volume sampling cut the open minutes where that is practicable. Write down why an alternative was rejected; that note is the decision.
Where the system still opens, enclose the charge, seal the pumps, and keep local exhaust at the bung and the sample point. Check capture at the rate you actually charge, not at a demonstration setting. Filter changes and vacuum breaks belong in the method, with a sequence, not as ad-hoc jobs.
Keep non-essential people out of the charge and drumming area. Fit respiratory protection to the vapour and aerosol hazard and to the concentration you expect, with fit testing and a change rule. Eye and skin protection has to match acid contact on the same tasks. Respiratory protection is the last layer on a charge point that can be enclosed.
Before December
Confirm who is exposed, including maintenance and contractors. Ask for a baseline against 2.5 mg/m³ (0.5 ppm) that includes open-handling days. A shift spent entirely on a sealed, automated batch will understate the campaign. Fix capture and written methods now; the new limit sharpens the number you must not exceed. It does not create the duty to manage the risk.
Train people on dichloroacetic acid by name. Ask the occupational-hygiene provider to state the method, the units (mg/m³ and ppm where both are supported), and whether a result is a shift average or a task reading.
Do not invent a short-term limit. Do not invent extra concentrations. Do not say your state has already switched unless the regulator has said so in writing.
FAQ
We only open it for sampling. Do we still need a group? If people can inhale vapour during sampling, yes. How often you sample changes the monitoring schedule. It does not remove the group.
Was there an older exposure standard? No. This is a new limit: 2.5 mg/m³ (0.5 ppm).
Is there a short-term exposure limit? Not on the published change for this listing. Peak control still sits with the task and the engineering.
When does the limit apply? Plan on exposure standards until 30 November 2026, and the new limit from 1 December 2026 once it is in force. Confirm that with your WHS regulator.
Sources
- Safe Work Australia, *Changes to Workplace Exposure Limits – May 2025*: https://www.safeworkaustralia.gov.au/sites/default/files/2025-05/changes_to_workplace_exposure_limits_-_may_2025.pdf
- Safe Work Australia, changes between exposure standards and exposure limits: https://www.safeworkaustralia.gov.au/safety-topic/managing-health-and-safety/workplace-exposure-limits-airborne-contaminants/changes-between-wes-and-wel
Next step
If dichloroacetic acid is charged, sampled, drummed or maintained on your site, book a consult to lock the exposure groups and a monitoring plan before the limit date.
Book a consult: anitechgroup.com · sales@anitechgroup.com
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