Chemical hazards

The use of chemical substances is principally ruled by the Law on chemical products (LChim, ref 813.1) and the Ordinance on chemical products (OChim, ref 813.11). The ordinance on the decrease of risks relative to chemical products (ORRChim, ref 814.81) lists some types of substances with a prohibited or strictly limited use. There are several important technical directives edited by the Federal Commission of coordination for safety at work (CFST) and by the SUVA.


Chemical hazards (GHS)

A hazard is a potential source of danger or harm. If chemical hazards go unrecognized, unexpected events resulting in personal injury and/or property damage can (and do) occur.

Interestingly, the very properties that make a chemical useful are often those that make it risky to use, so you must learn how to safely use chemicals that have significant inherent hazards.


The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is now used to define physical , health , and environmental hazards  for each chemical manufactured and sold.


It is the responsibility of the manufacturer or importer to identify and communicate the hazard(s) of each chemical they produce or sell. It is up to the user (you) to understand the information provided on the label and in the Safety Data Sheet (SDS)

The GHS is all about communicating hazards to users. Pictograms are pictures that represent a concept. The GHS uses nine pictograms to visually alert users to the chemical’s hazard class. GHS pictograms, along with the hazard classes they cover, are shown in Figure 1. For more information, please read the “what should I know” series that provide extended information about GHS classification and labelling.

“What should I know”:

  • Explosives
  • Self-reactive
  • Organic peroxide

Gas under pressure:

  • Compressed gas
  • Liquefied gas
  • Dissolved gas
  • Refrigerated liquefied gas

  • Carcinogenicity
  • Mutagenicity
  • Reproductive toxicity
  • Respiratory sensitizer
  • Target organ toxicity
  • Aspiration toxicity

  • Flammable
  • Pyrophoric
  • Self-heating
  • Emits flammable gas in contact with water
  • Self-reactive
  • Organic peroxides

  • Skin corrosion
  • burns
  • Eye damage
  • Corrosive to metal

  • Acute toxicity (fatal or toxic)

  • Oxidisers

  • Irritant (skin and eye)
  • Skin sensitizer
  • Acute toxicity (harmful)
  • Narcotic effects
  • Respiratory tract infection
  • Hazardous to ozone layer

  • Aquatic toxicity

Before ordering a chemical, review the associated hazards to ensure that appropriate safe conditions and controls are available in the lab. Many chemicals (list of chemicals under authorization) require a special authorization from the SCC to be purchased, used, and/or stored at EPFL. Include these ordering procedures as a part of your process planning to increase laboratory safety.

Working with hazardous chemicals

You will work with many hazardous chemicals at some stage of your work. How can you be expected to know the hazardous characteristics of so many different chemicals?

The first safety procedure when working with a chemical is ALWAYS to: 

  • look for substitutions with less hazardous chemicals
  • read the label
  • read the safety data sheet

Then, remember to:

  • Wear safety glasses, gloves and a lab coat, or other personal protective equipment required for your procedure.
  • Do not work alone. If you are alone in the lab or you are working during off-hours or weekends, follow the off-hours announcement procedure.
  • Be prepared for emergencies and know what action to take. Make sure that necessary supplies and equipment are available for handling small spills.
  • Whenever possible, use a fume hood.
  • Never let reactions run unattended unless they are well understood and a system to contain spills is in place (ex: in the event of power failure). A safety form for experiments left unattended must be displayed on the fume hood sash.
  • Wash hands with soap and water immediately after working with any laboratory chemicals, even if gloves have been worn.

Safety Data Sheet

Most commercial substances have detailed information prepared by the supplier, the Safety Data Sheet (SDS). The Law on chemical products (LChim) stipulates that the user is responsible for taking into account the safety information given by the supplier and taking the appropriate measures to protect themselves.

Preventive and emergency measures

It is mandatory to wear personal protective equipment (PPE) whenever you are in a chemistry lab:

  • A cotton lab coat with pressure buttons
  • Safety glasses (corrective goggles adapted to your view are payed by the EPFL (…)
  • Protective gloves (adapted to your work (for ex. hot or cold) and to the chemical you are working with (use our ‘Gloves Guide’ to find suitable gloves)
  • Wear long trousers to protect your legs from spills
  • Wear closed shoes adapted to lab work (don’t work in flip-flops, ballerinas or high heels)
  • Attach your hair if needed

The EPI must be adapted to your work.

For example when working with hydrofluoric acid, you need to wear, in addition to the standard protective equipment mentioned before:

  • an apron (Haberkorn 300926)
  • a face shield (G500-GU/150 and GF-1/151)
  • thick protective gloves (Butoject 898)

All EPI are available in the campus shops of the EPFL or the online shop. The EPFL puts a lot of effort into protecting you as much as possible in your labs. Do not hesitate to notify the SCC if you notice a fault in the PPE already in place. EPFL organizes controls, but you are in the labs all day and you should tell us about any problem or situation you think may be dangerous.

If you need special protection you can contact us for corrective measures.

For example:

Before starting to work in a lab, read and think before acting. Imagine what could go wrong so that you are prepared in a case of an accident or an emergency.

Locate the lab phone and know the emergency number.

Locate the safety issues, the safety showers, the eye-washer, the extinguisher, the fire blanket, the pharmacy and the sink.

Be sure to behave correctly in case of an evacuation (gas or fire).

Never work alone.

Purchasing chemicals

Never buy products directly from the supplier. Order your chemicals through your chemical store. (links to all chemical stores?)

Buying the products via EPFL has several advantages:

  • The product is labelled with a bar code, which is very important for the inventory of chemicals you have to do twice a year
  • The products have a preferential price for the EPFL

Transport of chemicals

Bottle carriers or baskets should be used to transport chemicals.

Bottles should be carried one at a time with both hands, one on the neck of the bottle and the other one underneath.

Chemicals moved between sites should be in their original outer packages, or otherwise protected from breakage or damage in a secondary container with sufficient absorbent material to contain a spill.

Storage of chemicals

Have a look at our chemicals storage page