Chemical Risk Assessment & Hazardous Substance Management
A Systematic Approach to Identifying, Assessing, and Controlling Chemical Hazards in the Workplace
Chemical risk assessment is the process of identifying which hazardous chemicals are present in a workplace, evaluating the risk they pose to worker health and safety, and determining the controls necessary to eliminate or minimise that risk. It is a legal requirement under the WHS Regulation 2025, a cornerstone of the PCBU's duty of care, and the document that connects the chemical register, Safety Data Sheets, monitoring programme, health surveillance plan, and engineering control strategy into a single management system.
The 5-Stage Chemical Risk Assessment Process
Stage 1: Chemical Inventory & Hazard Identification
Complete inventory of every hazardous chemical — purchased, process-generated, and environmental. GHS classification review. SDS currency check (within 5 years). Verification through workplace observation, not just document review.
Stage 2: Exposure Assessment
Determines who is exposed, by what route (inhalation, dermal, ingestion), at what concentration, for how long. Must consider all workers — not just operators — and non-routine conditions (maintenance, start-up, spills).
Stage 3: Risk Evaluation
Compares measured/estimated exposure against WELs. For substances without WELs, draws on ACGIH TLVs, international limits, or formal HHRA. Assesses additive effects of multiple substances with similar health effects.
Stage 4: Control Determination
Hierarchy of controls: elimination → substitution → isolation → engineering controls → administrative controls → PPE. Must specify controls, responsible person, timeline, verification method, and maintenance requirements.
Stage 5: Documentation, Communication & Review
Documented assessment accessible to workers and regulators. Active communication via toolbox talks and training. Review triggered by process change, new chemicals, WEL transition, incidents, or monitoring results indicating inadequate controls.
The Chemical Register
The chemical register is the foundational document — a record of every hazardous chemical with associated SDS, GHS classification, WES/WEL values, quantities, locations, and cross-references to risk assessments. The WEL transition requires a systematic review: every SDS referencing airborne exposure standards must be checked against incoming WEL values. Where the WEL is lower than the SDS-printed WES, the register must note the discrepancy and the assessment must be updated.
Emergency Preparedness
Emergency response plans must be substance-specific — containment and clean-up procedures for each spill type, first-aid treatments for acute exposure to each chemical, decontamination procedures, evacuation criteria, and emergency equipment locations. Drills should be conducted at least annually for workplaces with significant chemical hazards.
Review Your Chemical Risk Assessments
The December 2026 WEL transition requires every workplace that uses, handles, or generates hazardous chemicals to review its assessments, update its register, and verify its controls. The gap between compliant and non-compliant has never been narrower.