Recognise lab hazards, read GHS labels and Safety Data Sheets, choose PPE, and understand the training and records that keep labs safe.

Lab Safety Fundamentals

> **Awareness level only.** This lesson explains the ideas so you recognise them. It does not qualify you to do this work. Before you handle chemicals, biological materials or lab equipment for real, you need the training your employer or institution requires, and you must work under supervision until they sign you off.

## Why it matters

A lab may hold hundreds of chemicals, and many look alike: clear liquids, white powders. The label is your first warning of what a container can do to you. Before 1992, labels varied by country and supplier. The **Globally Harmonized System of Classification and Labelling of Chemicals (GHS)**, developed through the United Nations, gives the whole world one format. In the United States, OSHA's **Hazard Communication Standard** (HazCom, 29 CFR 1910.1200) adopts GHS for workplace labels and Safety Data Sheets. Most other countries have adopted it too (for example, CLP in the EU and WHMIS in Canada).

## Hazard classes

GHS sorts hazards into three groups:

- **Physical hazards:** flammable, explosive, oxidising, self-reactive, pyrophoric (ignites in air), gases under pressure, corrosive to metals.
- **Health hazards:** acute toxicity, skin corrosion or irritation, serious eye damage, sensitisation, carcinogenicity, mutagenicity, reproductive toxicity, organ toxicity, aspiration hazard.
- **Environmental hazards:** harmful to aquatic life (and, outside the US, the ozone layer).

Within a class, a **category** gives severity. Category 1 is the most severe: acute toxicity category 1 can kill in tiny amounts; category 4 is harmful.

## The six parts of a GHS label

1. **Product identifier:** the chemical or product name, matching its Safety Data Sheet.
2. **Signal word:** **Danger** (more severe) or **Warning** (less severe). A label has only one.
3. **Hazard statements:** standard phrases describing the hazard, each with a code, such as `H225 Highly flammable liquid and vapour` or `H314 Causes severe skin burns and eye damage`.
4. **Precautionary statements:** what to do, with P-codes: prevention (`P210 Keep away from heat, sparks, open flames`), response (`P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes...`), storage and disposal.
5. **Pictograms:** red-bordered diamonds with a black symbol.
6. **Supplier information:** name, address and phone number of the manufacturer or importer.

## The nine pictograms

| Pictogram | Means | Examples |
|---|---|---|
| Flame | flammable, self-heating, pyrophoric | ethanol, acetone |
| Flame over circle | oxidiser (feeds a fire) | hydrogen peroxide (concentrated), nitrates |
| Exploding bomb | explosive, self-reactive | some peroxides, azides |
| Gas cylinder | gas under pressure | nitrogen, CO2 cylinders |
| Corrosion | burns skin, damages eyes, corrodes metal | concentrated acids and bases |
| Skull and crossbones | acute toxicity (fatal or toxic) | sodium cyanide, methanol (in some categories) |
| Exclamation mark | irritant, sensitiser, harmful, narcotic effects | dilute acids, many solvents |
| Health hazard | carcinogen, mutagen, reproductive or organ toxicity, respiratory sensitiser | benzene, formaldehyde |
| Environment | toxic to aquatic life | many pesticides (not mandatory under OSHA HazCom) |

## Worked example: reading a label

A bottle of acetone shows: signal word **Danger**; the flame and exclamation mark pictograms; `H225 Highly flammable liquid and vapour`, `H319 Causes serious eye irritation`, `H336 May cause drowsiness or dizziness`; and precautions including `P210` (no ignition sources) and `P233` (keep container tightly closed).

What it tells you: keep it away from hot plates and flames, use it where vapours are controlled, wear eye protection, and close the bottle after use. The label does not tell you which glove material works or how to clean up a large spill; for that you go to the Safety Data Sheet (next lesson).

## Secondary containers

When you pour a chemical into a beaker, wash bottle or smaller bottle, that **secondary container** must also be labelled according to your lab's rules: at least the chemical name and main hazards, often the date and your initials. Unlabelled containers are one of the most common findings in lab inspections, and the cause of many "what was in this?" incidents.

## Other labels you will see

- **NFPA 704 diamond** (blue health, red flammability, yellow instability, white special hazards, rated 0 to 4) on doors and storage areas, aimed at emergency responders.
- **DOT/transport labels** on shipping boxes.
- **Biohazard, radiation and laser warning signs**, covered elsewhere in this course.

Note that the NFPA scale runs the opposite way to GHS categories: in NFPA, 4 is the most severe; in GHS, category 1 is.

## Common mistakes

- **Judging by smell or looks.** Many dangerous chemicals have no warning odour.
- **Ignoring the signal word.** "Danger" means take extra care.
- **Confusing GHS categories with NFPA numbers.**
- **Leaving secondary containers unlabelled**, even "just for a minute".

## Quick recap

- GHS gives one label format worldwide; OSHA HazCom requires it in US workplaces.
- A label has six parts: identifier, signal word, hazard statements, precautionary statements, pictograms, supplier.
- Learn the nine pictograms and what each means.
- Labels are the summary; the Safety Data Sheet has the detail.

Official source: OSHA Hazard Communication, https://www.osha.gov/hazcom (Checked on 2026-10-23.)


Read a GHS chemical label: the signal word, hazard and precautionary statements, and the nine pictograms.

Chemical hazards and the GHS label

GHS Pictograms Explained - The Hazard Communication Standard

HazCom and GHS Explained in 6 Minutes

Pick a common household product you have, such as isopropyl (rubbing) alcohol, a bleach cleaner or dish soap. Without opening it, find the manufacturer's name on the label.

Search for "<product name> safety data sheet" on the manufacturer's website and download the SDS (most manufacturers publish them). Check that the product name and supplier match.

Section 2: write down the signal word, the pictograms and two hazard statements.

Section 4: write down the first-aid instruction for eye contact.

Section 6 and 7: write down what to do for a small spill, and two storage conditions (for example temperature, keep away from, incompatible materials in section 10).

Section 8: write down the PPE it recommends (eye, skin, respiratory) and any exposure limit listed.

Section 9: find the flash point, if listed. Is the product flammable at room temperature?

Compare with a second product's SDS and note one way the two differ in hazards or PPE.

> **Awareness level only.** This lesson explains the ideas so you recognise them. It does not qualify you to do this work. Before you handle chemicals, biological materials or lab equipment for real, you need the training your employer or institution requires, and you must work under supervision until they sign you off.

## Why it matters

The label on a bottle gives you a summary. The **Safety Data Sheet (SDS)** gives you everything else: what is in it, how it can hurt you, what to wear, how to store it, what to do in a spill or fire, and first aid. Under OSHA's Hazard Communication Standard, manufacturers and importers must provide an SDS for every hazardous chemical, and employers must keep them **readily accessible** to workers on every shift. Knowing your way around one is a basic skill for every lab job, and you will be expected to read the SDS before using an unfamiliar chemical.

## One format, 16 sections

GHS fixed the order of the sections, so every SDS looks the same no matter who wrote it. (Older documents called "MSDS" had no standard layout.)

| # | Section | What you find |
|---|---|---|
| 1 | Identification | product name, uses, supplier, emergency phone |
| 2 | Hazard identification | GHS classification, signal word, pictograms, H and P statements |
| 3 | Composition | ingredients, CAS numbers, concentrations |
| 4 | First-aid measures | eyes, skin, inhalation, ingestion; symptoms |
| 5 | Fire-fighting measures | suitable extinguishers, combustion hazards |
| 6 | Accidental release measures | spill clean-up, PPE for the clean-up, containment |
| 7 | Handling and storage | safe handling, storage conditions, incompatibilities |
| 8 | Exposure controls / PPE | exposure limits (OSHA PEL, ACGIH TLV), ventilation, gloves, eye and respiratory protection |
| 9 | Physical and chemical properties | appearance, odour, pH, flash point, boiling point, vapour pressure |
| 10 | Stability and reactivity | conditions to avoid, incompatible materials, hazardous decomposition |
| 11 | Toxicological information | routes of exposure, effects, LD50 values |
| 12 | Ecological information | effects on the environment |
| 13 | Disposal considerations | how to dispose of it |
| 14 | Transport information | UN number, shipping class |
| 15 | Regulatory information | regulations that apply |
| 16 | Other information | revision date and notes |

OSHA does not enforce sections 12 to 15 (they fall under other agencies), but they are usually filled in.

## How to read one quickly

You rarely read an SDS top to bottom. Go to the section that answers your question:

- "Is this dangerous, and how?" Section **2**.
- "What do I wear?" Section **8** (gloves often name a material and a breakthrough time).
- "Where and how do I store it? What must it not touch?" Sections **7** and **10**.
- "Someone got it on them." Section **4**, and call for help.
- "It spilled." Section **6**, then your lab's spill procedure.
- "How do I get rid of it?" Section **13**, then your institution's waste rules.

## Worked example: isopropyl alcohol (70%)

Looking up a typical SDS for 70% isopropyl alcohol:

- **Section 2:** Danger. Flammable liquid category 2, eye irritation category 2A, may cause drowsiness. Pictograms: flame, exclamation mark.
- **Section 4:** eyes: rinse with water for several minutes, remove contact lenses if easy, continue rinsing, get medical advice if irritation persists.
- **Section 7:** keep away from heat and ignition sources, keep container closed, store in a cool, well-ventilated place.
- **Section 8:** safety glasses; gloves such as nitrile for incidental contact; use with good ventilation; an exposure limit (for isopropanol, OSHA lists a PEL of 400 ppm as an 8-hour average).
- **Section 9:** flash point around 20 °C (68 °F): it can give off enough vapour to ignite at room temperature.
- **Section 10:** incompatible with strong oxidisers.

Putting it together: store it in a flammables cabinet away from oxidisers, keep it away from hot plates, and wear eye protection.

## Where to find SDSs

- Your lab's SDS binder or electronic SDS system (ask where it is on your first day).
- The supplier's website (search the product name and "SDS").
- Reference resources such as PubChem's Laboratory Chemical Safety Summary for background. Always use the SDS for the exact product and supplier you have, because mixtures and concentrations differ.

## Beyond the SDS

An SDS describes the chemical, not your procedure. Heating, mixing or scaling up can create hazards the SDS does not cover. That is why labs also use standard operating procedures and risk assessments (module 3), and why you ask your supervisor before using a chemical in a new way.

## Common mistakes

- **Using an SDS for a different concentration or supplier.**
- **Reading only section 2** and missing incompatibilities in section 10.
- **Not knowing where the lab's SDSs are kept** until there is an emergency.
- **Trusting an out-of-date SDS.** Check the revision date in section 16.

## Quick recap

- Every hazardous chemical has an SDS with 16 sections in a fixed order.
- Section 2 hazards, 4 first aid, 6 spills, 7 storage, 8 PPE, 10 incompatibilities, 13 disposal.
- Use the SDS for the exact product you have, and find your lab's SDS collection on day one.

Official source: OSHA Hazard Communication, https://www.osha.gov/hazcom (Checked on 2026-10-23.)

## Try it

Open the **Do** tab and find key facts in the SDS of a household product.


Find hazards, PPE, storage, spill and first-aid information in the 16 sections of a Safety Data Sheet.

Reading a Safety Data Sheet

SAFETY DATA SHEETS TRAINING VIDEO | By Ally Safety

Chemical Safety Information Resources | ACS College Safety Video #2

> **Awareness level only.** This lesson explains the ideas so you recognise them. It does not qualify you to do this work. Before you handle chemicals, biological materials or lab equipment for real, you need the training your employer or institution requires, and you must work under supervision until they sign you off.

## Why it matters

Biological technicians, biochemists and medical laboratory technologists work with microorganisms, cell lines and human samples that can cause infection. You cannot see the hazard, so labs rely on agreed levels of containment. In the US, the reference is **Biosafety in Microbiological and Biomedical Laboratories (BMBL)**, published by the CDC and NIH (currently the 6th edition). It defines four **biosafety levels (BSL-1 to BSL-4)**, each adding practices, safety equipment and facility features on top of the level below.

## Risk groups vs biosafety levels

These are related but not the same:

- A **risk group** (RG1 to RG4) classifies an *agent* by how dangerous it is: whether it causes disease in healthy adults, how serious, whether it spreads easily, and whether treatment or vaccines exist.
- A **biosafety level** is the set of *containment conditions* chosen for a particular piece of work, based on a **risk assessment** of the agent and the procedure.

Usually RG2 agents are handled at BSL-2, but a procedure that makes aerosols or uses large volumes can call for more containment. The institution's biosafety officer and Institutional Biosafety Committee make that call, not the individual.

## The four levels

| Level | Typical agents | Key practices and equipment | Facility |
|---|---|---|---|
| **BSL-1** | agents not known to cause disease in healthy adults, e.g. non-pathogenic *E. coli* K-12 strains, *Bacillus subtilis* | standard microbiological practices: handwashing, no eating or drinking, no mouth pipetting, decontaminate work surfaces; lab coat, gloves, eye protection as needed | open bench, sink, door |
| **BSL-2** | moderate hazard, spread by contact, ingestion or needle-stick, e.g. *Staphylococcus aureus*, *Salmonella*, hepatitis B virus, most human blood and tissue work | BSL-1 plus restricted access, biohazard signs, sharps precautions, **biosafety cabinet** for aerosol-generating work, documented training | self-closing doors, eyewash, autoclave available |
| **BSL-3** | serious or potentially lethal disease by inhalation, e.g. *Mycobacterium tuberculosis* | BSL-2 plus all open work in a biosafety cabinet, respiratory protection as required, medical surveillance, strict access control | controlled access through two self-closing doors, directional inward airflow, exhaust not recirculated |
| **BSL-4** | dangerous and exotic agents with high risk of life-threatening disease and no vaccine or treatment, e.g. Ebola virus | BSL-3 plus clothing change, shower on exit, Class III cabinet or positive-pressure suit | separate building or isolated zone, dedicated air and decontamination systems |

Only a small number of BSL-4 labs exist worldwide. As a beginner you will work at BSL-1 or BSL-2.

## Worked example: matching work to a level

1. A teaching lab grows a non-pathogenic *E. coli* strain for a plasmid experiment. **BSL-1**: standard practices on an open bench.
2. A hospital lab tests patient blood samples. Human blood can carry bloodborne pathogens, so it is handled under **BSL-2** practices with **Universal (Standard) Precautions**, and US employers must also follow OSHA's Bloodborne Pathogens Standard (29 CFR 1910.1030), which includes annual training and offering the hepatitis B vaccine.
3. A research lab grows *M. tuberculosis* cultures. Transmission is by inhalation, so **BSL-3**.
4. A BSL-2 agent is to be spun in large volumes, which creates aerosols. The risk assessment may require sealed rotors opened in a biosafety cabinet, or enhanced practices; the biosafety officer decides.

## The biohazard symbol

The three-ringed biohazard symbol marks rooms, freezers, waste and equipment containing biological hazards. At BSL-2 and above, the door sign also lists the agents, the level, required PPE and an emergency contact.

## Standard microbiological practices (every level)

- Wash hands after work and before leaving.
- No eating, drinking, applying cosmetics or handling contact lenses in the lab.
- Never mouth-pipette; use mechanical pipetting devices.
- Minimise splashes and aerosols.
- Decontaminate work surfaces after work and after any spill.
- Decontaminate waste before disposal (often by autoclave).
- Handle sharps with extreme care.

## Common mistakes

- **Treating "BSL-1" as "no rules".** Standard practices still apply.
- **Confusing risk group and biosafety level**, or picking a level yourself instead of following the institution's risk assessment.
- **Forgetting human samples are BSL-2 work** even when the patient seems healthy.
- **Working outside a biosafety cabinet** when a procedure makes aerosols.

## Quick recap

- BMBL (CDC/NIH) defines BSL-1 to BSL-4; each level adds practices, equipment and facility features.
- Risk group describes the agent; biosafety level describes the containment chosen after a risk assessment.
- Most entry-level work is BSL-1 or BSL-2; human blood and tissue are handled as BSL-2.

Official source: CDC and NIH, BMBL, https://www.cdc.gov/labs/bmbl/index.html (Checked on 2026-10-23.)


Match biological agents, practices and facilities to biosafety levels 1 to 4.

Biosafety levels

Understanding Biosafety Levels

NEIDL: Biosafety Level 4

Read GHS labels and pictograms, find what you need in a Safety Data Sheet, and match biological work to biosafety levels.