COSHH assessment vs safety data sheet
Reviewed September 2026 · Written by Complys and checked against HSE and legislation.gov.uk guidance (sources below).
It is one of the most common and most costly misunderstandings in COSHH: keeping a folder of safety data sheets and believing that means you are "COSHH compliant". You are not. A safety data sheet and a COSHH assessment are two different things, produced by two different people, for two different purposes. Here is the difference, and how the one feeds the other.
What a safety data sheet is
A safety data sheet (SDS, sometimes still called an MSDS) is a standardised document the supplier or manufacturer of a hazardous substance must provide. Under UK REACH, suppliers must provide an SDS for hazardous chemicals supplied for use at work, and SDS duties can also apply to some mixtures that are not themselves classified as hazardous but contain hazardous substances. It follows a fixed format of 16 sections covering identification, hazards, composition, first-aid measures, firefighting, accidental release, handling and storage, exposure controls and personal protection, physical properties, stability, toxicological information, ecological information, disposal, transport, regulatory information and other information.
Crucially, the SDS is generic. It describes the substance as the supplier ships it, for all possible customers. It knows nothing about your workplace.
What a COSHH assessment is
A COSHH assessment is your assessment, required by regulation 6 of the Control of Substances Hazardous to Health Regulations 2002 (in Northern Ireland, the Control of Substances Hazardous to Health Regulations (Northern Ireland) 2003). It assesses the risk to health from the way a substance is actually used or created in your workplace, and sets out the steps you will take to prevent or adequately control exposure. It is specific to your task, your quantities, your process, your ventilation, and the people who are exposed. See how to do a COSHH assessment.
Why an SDS is not a COSHH assessment
The SDS cannot answer the questions COSHH actually asks, because only you know the answers. A safety data sheet does not know:
- what task you are doing with the substance, or how often;
- how much you use, and whether it is decanted, sprayed, heated or mixed;
- whether your workroom is ventilated, or the work is done in a confined space;
- who is exposed, for how long, and whether anyone is especially at risk;
- what other substances it is used alongside;
- what control measures you already have, and whether they are adequate.
Two businesses using the identical product from the identical SDS can have completely different risks — and therefore completely different COSHH assessments — because they use it differently. That is exactly why the law requires the assessment on top of the SDS.
How to use the SDS to build the assessment
The right relationship is: the SDS is one of your most important inputs, and the COSHH assessment is the output. When building the assessment, the most useful SDS sections are:
- Section 2 (hazard identification) — the classification and hazard statements that tell you how the substance can harm health. See COSHH symbols explained.
- Section 8 (exposure controls / personal protection) — any exposure limits and the supplier's advice on engineering controls and PPE.
- Section 11 (toxicological information) — the health effects, routes of exposure and target organs.
- Sections 4, 6, 7 and 13 — first aid, spillage, safe handling/storage and disposal, which feed your emergency and control arrangements.
You then apply that information to your own task: decide whether exposure can be prevented (elimination or substitution), and if not, what controls adequately manage it, following the hierarchy of control. Where a substance has a Workplace Exposure Limit (WEL), check the current figure in HSE's EH40 rather than relying on the SDS, which can be out of date or quote a limit from another country.
The mistake to avoid
Keeping a binder of safety data sheets is good practice — you should retain them — but it is not compliance with COSHH. An enforcing inspector who asks for your COSHH assessments will not accept a stack of supplier SDSs in their place. Equally, do not simply copy the SDS wording into an "assessment": a document that just restates the generic supplier information, without addressing your task and controls, is not suitable and sufficient either.
A quick comparison
| Safety data sheet | COSHH assessment |
|---|---|
| Produced by the supplier/manufacturer | Produced by you, the employer |
| Generic to the substance | Specific to your task and workplace |
| Information about the substance | Assessment of the risk and the controls |
| Required under CLP / REACH (supplier duty) | Required under COSHH regulation 6 (employer duty) |
| An input | The output that keeps people safe |
Turn a safety data sheet into a real COSHH assessment
Complys builds a workplace-specific COSHH assessment for each substance — using the SDS hazard data as the input, then adding the task, controls, PPE, exposure limits and emergency actions the SDS can't know. Every assessment is stored in a register with its review date, and can be downloaded as a PDF. The competent-person judgement stays yours; Complys does the structure and the record-keeping.
Sources
- HSE — COSHH, CLP and REACH (safety data sheets)
- HSE — COSHH assessments
- HSE — EH40/2005 Workplace exposure limits
- Control of Substances Hazardous to Health Regulations 2002
This guide is general information, not legal advice. COSHH and chemical-classification rules change over time — always check the current HSE and legislation.gov.uk guidance for your work.
COSHH assessment vs safety data sheet — FAQs
Is a safety data sheet a COSHH assessment?
No. A safety data sheet (SDS) is generic information the supplier provides about a substance. A COSHH assessment is your own assessment of the risk from how that substance is actually used in your workplace, and the controls you will put in place. The SDS is an input to the assessment, not the assessment itself.
Do I still need a COSHH assessment if I have the safety data sheet?
Yes. Filing the SDS does not discharge your duty under regulation 6 of COSHH. The SDS tells you about the substance; it cannot tell you about your task, your quantities, your ventilation, who is exposed or for how long — which is what the assessment has to address.
What is a safety data sheet for, then?
The SDS gives you the hazard information and supplier advice you need to build the assessment — hazard classification, exposure controls, first aid, storage, spillage and disposal. It is a key source of information, and you should keep it, but it is a starting point.
How many sections does a safety data sheet have?
A standard SDS has 16 defined sections, from identification and hazards through to handling, exposure controls and disposal. Sections 2, 8 and 11 (hazards, exposure controls and toxicological information) are the most useful when building a COSHH assessment.
Where do workplace exposure limits come from?
Some substances have a Workplace Exposure Limit (WEL) published by HSE in EH40. The SDS may quote a limit, but you should check the current EH40 value, because SDS figures can be out of date or from another country.