The 16 Sections of a Safety Data Sheet (SDS) Explained

A safety data sheet (SDS) is the detailed technical document behind every hazardous product — and under WHMIS 2015 it always has the same 16 sections in the same order. Safety data sheets are one of the WHMIS key components. This guide explains what each section tells you, and which ones to check first in an emergency.

The 16 sections at a glance

#	Section	What it tells you
1	Identification	Product name, supplier name and address, emergency phone number, recommended use and restrictions — must match the supplier label
2	Hazard identification	Classification, hazard pictograms, signal word, hazard and precautionary statements
3	Composition / information on ingredients	Chemical names, CAS numbers and concentrations of the hazardous ingredients
4	First-aid measures	What to do after inhalation, skin contact, eye contact or ingestion, and the symptoms to expect
5	Fire-fighting measures	Suitable and unsuitable extinguishing media, hazardous combustion products, protection for fire-fighters
6	Accidental release measures	Spill response — personal precautions, containment and clean-up methods
7	Handling and storage	Safe handling precautions and storage conditions, including incompatible materials
8	Exposure controls / personal protection	Occupational exposure limits, engineering controls and the PPE required
9	Physical and chemical properties	Physical state, odour, flash point, pH, boiling and melting points, vapour pressure and more
10	Stability and reactivity	Chemical stability, conditions to avoid, incompatible materials, hazardous decomposition products
11	Toxicological information	Routes of exposure, symptoms, immediate, delayed and chronic effects, and numerical toxicity measures
12	Ecological information	Ecotoxicity, persistence, bioaccumulation and mobility (heading mandatory, content optional in Canada)
13	Disposal considerations	Safe disposal of the product and contaminated packaging (heading mandatory, content optional in Canada)
14	Transport information	UN number, shipping name, transport hazard class, packing group (heading mandatory, content optional in Canada)
15	Regulatory information	Other safety, health and environmental regulations applying to the product (heading mandatory, content optional in Canada)
16	Other information	The date of the latest revision of the SDS

Sections 1–3: identification and hazards

• Section 1 — Identification: the product identifier, the Canadian supplier's name, address and phone number, an emergency number with any restrictions on its use, and the product's recommended use.
• Section 2 — Hazard identification: the classification — class, category, subcategory — with the label elements: pictogram or symbol name, signal word, hazard and precautionary statements.
• Section 3 — Composition: the hazardous ingredients by chemical name, CAS number and concentration, subject to the confidential business information rules.1

How workers use them: these three sections answer "am I reading the right document, and what is this product?" Match the product name in section 1 to the name on the container before you rely on anything else — an SDS for a similar product from the same supplier is worse than no SDS. Then check section 1's recommended use: if you are using the product differently, the advice in the rest of the sheet may not apply, and you should ask your supervisor.

Sections 4–6: emergency response

• Section 4 — First-aid measures: what to do after inhalation, skin contact, eye contact or ingestion, the symptoms to expect — immediate and delayed — and whether medical attention is needed.
• Section 5 — Fire-fighting measures: suitable and unsuitable extinguishing media, the hazards the product creates in a fire, and the protection fire-fighters need.
• Section 6 — Accidental release measures: spill response — personal precautions, protective equipment, and the methods and materials for containment and clean-up.

These are the three sections to know before an incident, not during one. Nobody reads an SDS with chemical in their eye. Before you work with a product for the first time, read section 4 and know how long you are expected to flush, whether to induce vomiting (almost never), and whether the exposure needs medical attention even if you feel fine. Check section 5 for whether water is the wrong thing to use, and section 6 for whether your spill kit actually contains the right absorbent.

Sections 7–10: safe handling and properties

• Section 7 — Handling and storage: precautions for safe handling and the conditions for safe storage, including incompatible materials.
• Section 8 — Exposure controls / personal protection: the section workers consult most — exposure limits, required engineering controls, and the respiratory, eye, skin and hand protection that goes with them.
• Section 9 — Physical and chemical properties: physical state, odour, flash point, pH, viscosity, solubility, vapour pressure, density and more.
• Section 10 — Stability and reactivity: chemical stability, possible hazardous reactions, conditions to avoid such as shock or static discharge, and hazardous decomposition products.

How workers use them: this group answers pre-task and storage questions. Section 8 tells you what to wear and what ventilation you need before you start. Sections 7 and 10 together tell you what the product must not be stored beside — the acid and the bleach on the same shelf is a section 10 failure, not bad luck. Section 9 is what an emergency responder or hygienist will ask you for.

Sections 11–16: supplementary information

• Section 11 — Toxicological information: the health effects and the data behind them — routes of exposure, symptoms, immediate, delayed and chronic effects, and numerical toxicity measures.
• Sections 12 to 15: ecological information, disposal, transport and regulatory information.
• Section 16 — Other information: the date of the latest revision — the single most useful field when you audit an SDS library.

Here is the Canada-specific nuance most guides miss: the headings for sections 12 to 15 must appear on every SDS, but under Canadian regulations the supplier has the option not to provide the content.

So an SDS with four near-empty sections in the middle is routine — and nothing is wrong with it. Everywhere else on the sheet, the supplier must address each required information element, using "not available" where the data could not be found and "not applicable" where the element is irrelevant — and those two phrases mean different things, so a supplier should not abbreviate either to "NA". 1

Who must provide SDSs — and when they must be updated

Suppliers must provide an SDS with every hazardous product at the time of sale, in English and French, either as one bilingual sheet or as two sheets delivered together. It cannot be provided as a link: emailing the sheet or handing over a USB is acceptable, pointing the purchaser at a website is not.

Employers must make sure every hazardous product entering the workplace has a current SDS, and must keep those sheets readily available to exposed workers and to the health and safety committee or representative. Digital SDS systems are fine provided workers can actually reach and use them — the exact conditions sit with the employer duties. 1

The update rule changed with WHMIS 2015 and is still widely misquoted. Under WHMIS 2015 a safety data sheet no longer expires after three years — that was a WHMIS 1988 rule. Instead, the SDS must be accurate at the time of every sale, and the supplier must update it within 90 days of becoming aware of "significant new data" about the product's hazards (labels: 180 days).

Those periods are temporary exemptions rather than quiet grace periods: if the product is sold before the sheet has been corrected, the supplier must give the purchaser a separate written document setting out the required changes and the date the new data became available.

Employers who receive such a notice must apply the changes to the copies they hold. 12

Several provinces and territories add their own employer-side currency duties on top of the federal supplier rule — check the WHMIS provisions in your jurisdiction's OHS legislation. Whichever applies to you, an annual review of your SDS library is the practical standard. 1

Why every SDS looks the same

The 16-section format is not a Canadian invention. It comes from the GHS standardized format — the UN system Canada adopted in 2015 — which fixed the number of sections, their order and their headings. That is why an SDS from a supplier you have never dealt with needs no orientation: section 8 is always PPE, section 13 is always disposal. Expect the structure to match; check the substance against Canadian requirements.

Reading an SDS is a WHMIS skill

Being able to find the right information on a safety data sheet, quickly, is part of WHMIS certification — and it is the skill that matters most in the minutes after something goes wrong. The online course covers it in about 1 hour 45 minutes, with the certificate issued on completion.