How to Read a Safety Data Sheet (SDS): A Practical Guide

What Is a Safety Data Sheet?

A Safety Data Sheet (SDS) is the standardised document that tells you everything the manufacturer knows about the hazards of a chemical product and how to handle it safely. Every commercial chemical product sold in the UK must come with one. Your supplier is legally required to provide it free of charge under the UK REACH regulation.

If you are writing COSHH assessments, the SDS is your primary source of hazard information. Without it, you are guessing — and guesswork does not meet the "suitable and sufficient" standard the HSE expects. Our step-by-step COSHH assessment guide references the SDS at almost every step, because that is where the facts live.

The 16 Sections of a Safety Data Sheet

Every SDS follows a standardised 16-section format, set out in Annex II of the UK REACH regulation (retained from EU REACH). The sections are always in the same order, regardless of the manufacturer or product.

Here is what each section contains and how useful it is for your COSHH assessment.

Section 1 — Identification of the substance/mixture and of the company

The product name, intended uses, and the manufacturer or supplier's contact details. Also includes the emergency telephone number.

COSHH use: Record the product name and supplier details on your assessment. Use the emergency phone number in your emergency procedures section.

Section 2 — Hazards identification

The GHS classification of the product: hazard pictograms, signal word (Danger or Warning), H-phrases (hazard statements), and P-phrases (precautionary statements). This section also notes any hazards not covered by the GHS classification.

COSHH use: Critical. This is the first section you should read. It gives you the hazard classification you need for your assessment — what pictograms to record, what the substance can do to people, and the specific H-phrases that describe each hazard. If a product carries H334 ("may cause allergy or asthma symptoms or breathing difficulties if inhaled"), that single H-phrase triggers health surveillance requirements in your assessment.

Section 3 — Composition/information on ingredients

Lists the chemical components of the mixture, with their CAS numbers and concentration ranges. For single-substance products, gives the chemical identity.

COSHH use: Useful for checking whether the product contains any ingredient with a Workplace Exposure Limit (WEL) listed in EH40. Also helps if you need to look up toxicology data for a specific ingredient.

Section 4 — First-aid measures

What to do if someone is exposed: actions for inhalation, skin contact, eye contact, and ingestion. Notes any symptoms to watch for and whether immediate medical attention is needed.

COSHH use: Critical. Copy the first-aid measures directly into the emergency procedures section of your COSHH assessment. These are the manufacturer's specific recommendations — use them rather than writing generic "seek medical attention" instructions.

Section 5 — Firefighting measures

Suitable extinguishing media, specific hazards during a fire (e.g., toxic fume released on combustion), and guidance for firefighters.

COSHH use: Relevant if you store significant quantities or work with flammable substances. Otherwise, a quick check to note any unusual fire risks.

Section 6 — Accidental release measures

Spill and leak response: personal precautions, environmental precautions, and clean-up methods.

COSHH use: Feeds into the emergency procedures section of your assessment. Particularly important for corrosive or environmentally hazardous substances.

Section 7 — Handling and storage

Safe handling practices and conditions for safe storage, including incompatible materials (e.g., "do not store with acids").

COSHH use: Critical. This section tells you the administrative controls and storage requirements you should include in your assessment. If it says "use only in well-ventilated areas," that is an engineering control requirement. If it says "keep away from oxidising agents," that affects your storage arrangements.

Section 8 — Exposure controls/personal protection

Workplace Exposure Limits (WELs) for the substance or its components, recommended engineering controls (ventilation type and specifications), and specific PPE recommendations — glove type and material, respiratory protection type, eye protection type.

COSHH use: Critical. This section directly informs the control measures section of your assessment. It tells you the WEL you need to check against, the type of ventilation recommended, the specific glove material that provides adequate protection (not all gloves protect against all chemicals), and whether respiratory protection is needed. If the SDS specifies "nitrile gloves, minimum 0.4mm thickness," record that — do not just write "gloves."

Section 9 — Physical and chemical properties

Appearance, odour, pH, boiling point, flash point, vapour pressure, and other physical data.

COSHH use: Gives you practical context. A high vapour pressure means the substance evaporates readily and inhalation risk is higher. A low flash point means flammability is a concern. The pH tells you about corrosivity.

Section 10 — Stability and reactivity

Conditions to avoid (heat, light, moisture), incompatible materials, and hazardous decomposition products.

COSHH use: Relevant for storage decisions and for identifying situations where a normally safe substance could become dangerous. For example, some cleaning products decompose to release toxic gases when heated or mixed with incompatible products.

Section 11 — Toxicological information

Detailed health effects data: acute toxicity values (LD50, LC50), whether the substance is a skin or respiratory sensitiser, whether it is carcinogenic, mutagenic, or toxic to reproduction (CMR), and the specific health effects by exposure route.

COSHH use: Critical. This section tells you the severity of the health risk, which feeds directly into your risk evaluation. If the substance is classified as a respiratory sensitiser, you need health surveillance. If it is a carcinogen, you need enhanced controls and possibly 40-year record retention. The toxicological data here gives you the "why" behind the hazard classification in Section 2.

Section 12 — Ecological information

Environmental toxicity, persistence, bioaccumulation, and mobility in soil.

COSHH use: Relevant mainly for disposal procedures and spill response. If the product is classified as very toxic to aquatic life (H400 or H410), your spill procedures need to prevent it entering drains or watercourses.

Section 13 — Disposal considerations

Waste treatment methods and any special disposal requirements.

COSHH use: Feeds into your disposal procedures. Particularly relevant for concentrated chemicals that cannot be poured down the drain.

Section 14 — Transport information

UN number, proper shipping name, transport hazard class, and packing group.

COSHH use: Only relevant if you transport hazardous substances between sites. For most SMEs, this section can be noted and filed.

Section 15 — Regulatory information

Safety, health, and environmental regulations specific to the substance. Lists any UK/EU regulatory requirements beyond REACH and CLP.

COSHH use: Worth checking for any additional regulatory obligations you might not be aware of.

Section 16 — Other information

Revision history, abbreviations used, and any other information the manufacturer considers relevant.

COSHH use: Check the revision date. If the SDS is more than five years old, request a current version from your supplier — the product may have been reformulated.

The Five Sections That Matter Most for COSHH

If you are short on time, these are the five sections to read carefully for every substance:

Section	What you get from it
Section 2 — Hazards identification	GHS classification, pictograms, H-phrases — the core hazard data for your assessment
Section 4 — First-aid measures	Specific emergency actions to include in your assessment
Section 7 — Handling and storage	Safe working procedures and storage requirements
Section 8 — Exposure controls/PPE	WELs, ventilation requirements, specific PPE recommendations
Section 11 — Toxicological information	Whether the substance causes sensitisation, cancer, or other chronic effects — determines health surveillance requirements

Read these five sections thoroughly. Skim the rest for anything relevant to your specific situation.

How to Extract Information for Your COSHH Assessment

Here is a practical workflow for turning an SDS into a COSHH assessment entry:

Step 1: Open Section 2. Record every hazard pictogram, the signal word, and every H-phrase. If you are unsure what a pictogram or H-phrase means in practical terms, our hazard label decoder provides plain-English explanations.

Step 2: Check Section 11 for sensitisation, CMR classification, or any chronic health effect. If the substance is a respiratory sensitiser, flag that health surveillance will be required.

Step 3: Read Section 8. Note the WEL (if any), the recommended ventilation type, the specific glove material and thickness, and any respiratory protection requirements. These become your control measures.

Step 4: Read Section 7. Note any handling restrictions ("use only in well-ventilated areas," "avoid contact with skin") and storage requirements ("keep container tightly closed," "store away from acids"). These become administrative controls and storage procedures.

Step 5: Read Section 4. Copy the first-aid measures for each exposure route (skin, eyes, inhalation, ingestion) into your emergency procedures.

Step 6: Check Section 3 for ingredients with their own WELs. A product might not have an overall WEL, but an individual ingredient might — check against EH40.

Common Confusion Points

"I cannot find a WEL for this product"

Most commercial products do not have a single WEL because they are mixtures, not pure substances. Check Section 3 for individual ingredients, then look each one up in EH40. If none of the ingredients have WELs, you still need to assess the risk — the absence of a WEL does not mean the substance is safe.

"The SDS says one thing but the label says another"

The SDS and the label should be consistent, but they serve different purposes. The label gives the end-user the essential hazard information at a glance. The SDS gives the detailed data. If they contradict each other, contact the supplier for clarification — and use the more conservative (more hazardous) classification in the meantime.

"My SDS is from 2018"

Chemical formulations change. Hazard classifications get updated. An SDS from 2018 may not reflect the current version of the product. Request an updated version from your supplier. Under REACH, suppliers must provide a revised SDS whenever significant new information becomes available. If you are managing many products, an outdated SDS collection is one of the most common COSHH mistakes inspectors find.

"I have a process-generated substance — there is no SDS"

Correct. Wood dust, welding fume, flour dust, and other process-generated substances do not have SDSs because they are not commercial products. For these, use the HSE's COSHH Essentials guidance sheets and EH40 as your reference sources instead.

Your Right to an SDS

Under Article 31 of the UK REACH regulation, suppliers must provide an SDS free of charge for any substance or mixture classified as hazardous. They must provide it in English, and it must be current. If a supplier refuses or fails to provide one, they are breaking the law.

Keep a copy of every SDS for every product you use. Organise them — by product name, by supplier, or by area of use — so you can find them quickly during an HSE inspection or when reviewing your COSHH assessments.

Putting It All Together

The SDS is the factual foundation of every COSHH assessment you write. Get comfortable reading Sections 2, 4, 7, 8, and 11, and the rest of the assessment process becomes significantly easier. You are not inventing hazard information — you are extracting it from the document the manufacturer is legally required to provide.

COSHHmate is being built to streamline this process. The guided assessment builder will help you pull the right information from each SDS into the right fields, so nothing gets missed and nothing gets guessed.

If you want COSHH assessments based on solid data rather than assumptions, join the waitlist to be first to know when COSHHmate launches.