What counts as a hazardous substance, which NZ rules apply and the records to keep so you're ready when WorkSafe visits.
In NZ, hazardous substances are products that can harm people or the environment because they're explosive, flammable, oxidising, toxic, corrosive or ecotoxic.
That covers more than factory chemicals. Diesel, LPG, solvents, cleaning products and farm sprays all count, so most workplaces hold at least a few.
The EPA approves substances and sets the rules for their labels and safety data sheets. WorkSafe enforces the workplace rules, including what you keep on file. This guide covers both.
Two laws do most of the work. The Hazardous Substances and New Organisms (HSNO) Act 1996 covers approving and classifying substances. The Health and Safety at Work (Hazardous Substances) Regulations 2017 set the rules for using them at work.
The EPA looks after the HSNO side, including the label, safety data sheet and packaging rules that suppliers follow. WorkSafe enforces the workplace regulations, which sit on top of the usual approach to controlling hazardous substances: remove the risk first, then reduce what’s left.
The regulations put most duties on the PCBU, short for person conducting a business or undertaking. That's the business, organisation or self-employed person running the work. The PCBU duties explain what else sits with them.
WorkSafe's guidance walks through the duties in order. The Hazardous Substances Toolbox adds free tools, including an inventory workbook and a calculator.
Every approved substance gets a hazard class, based on what makes it dangerous:
Class 1: explosives
Classes 2 to 5: flammables and oxidisers
Classes 6 and 8: toxic and corrosive substances
Class 9: ecotoxic substances, which harm the environment
Your supplier's safety data sheet states the class of each product you buy, so you don't have to work it out yourself.
WorkSafe's farm findings show where businesses slip. In 2025, 39% of assessments needed improvement on hazardous substances. Of the improvement notices issued, 94% related to missing safety data sheets or chemical inventories.
Two records matter most.
You need a current SDS for every hazardous substance in your workplace, whatever the quantity. Get it from the supplier the first time the substance arrives, and again if its information changes.
Everyone who could be exposed has to reach it easily. A locked cupboard or a restricted part of your computer system doesn't count. If workers travel between sites, a condensed version such as a product safety card works for emergencies.
An inventory lists every hazardous substance you use, handle, manufacture or store, including hazardous waste. For each substance, record:
the product or chemical name, and the UN number if there is one
the maximum amount likely to be on site
where it's kept
any storage or segregation needs, such as substances it can't sit next to
a current SDS, or a condensed version of its key information
Emergency services must be able to get to the inventory quickly. Consumer products used in household-sized amounts are exempt. WorkSafe's interpretive guidelines cover the detail.
Keep the SDS with the inventory so both are easy to find. A safety data sheet template can help you record each chemical's hazards, first aid and handling steps in one place. It doesn't replace your supplier's SDS, so keep both.
Review your controls at least every five years, and sooner if an SDS or your inventory changes significantly. Some records also have set retention periods. Exposure and health monitoring records, for example, must be kept for 30 years, or 40 for asbestos, under WorkSafe's risk guidelines.
Keep the supplier's label on every container and make sure it stays readable. If you decant a substance into a portable container of 40 litres or less, label it in English with the product name, hazard pictograms and hazard statements. Never use food or drink containers.
Some substances and quantities need warning signs. Keep them clean, in good repair and up to date when the type, class or quantity on site changes.
Storage rules depend on the class and how much you hold. Above set quantities, substances must go in a hazardous substance location (HSL) once they've been on site for more than 24 hours. You notify WorkSafe when you establish one, and many HSLs need a location compliance certificate. If you hold certain quantities, you also need an emergency response plan with your inventory and a site plan attached.
Don't guess the thresholds. The Hazardous Substances Calculator works out which controls apply from the substances and quantities you enter.
Only for the most dangerous substances. The old "approved handler" is now a certified handler, and it's required for fewer substances. These are the ones needing a controlled substance licence (most explosives, fumigants and pest control poisons such as 1080) and highly toxic class 6.1A and 6.1B substances. Certified handler requirements explain how workers qualify.
Everyone else who handles hazardous substances still needs information, training and instruction, plus supervised practice. It should cover the hazards, safe handling and storage, the right protective equipment and what to do in an emergency. Keep training records for as long as the person works for you. Structured workplace safety training makes that easier.
Hazardous substances are a named focus for WorkSafe’s 2026 farm visits, which run from October to December. WorkSafe’s announcement doesn’t say what else inspectors might check, so last year’s results are the best guide.
Those results point at paperwork. The most common problem was missing safety data sheets or chemical inventories.
WorkSafe’s assessments usually start with a conversation, then a walk around to check what you’ve said matches what’s there. If something looks off, the inspector looks closer and may ask for your documents.
Before a visit, check you can show:
a current SDS for every substance, easy to reach
an inventory with quantities and locations
readable labels on every container
training records for workers who handle substances
signs and storage that match what's on site
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