Our laboratory is full of signs isn’t it? Be it the chemical bottles or the signs near the basin, they are everywhere.  But that’s a good thing and is important for our safety. These signs tell you about the properties of the product you are about to use so that you can be cautious while you use it. You can also use them to label bottles with specific signs after you made a new solution to keep others informed.

I remember my first days in the lab – lost in the signs. It took me some time to figure out the details of all the signs that I was handling. Here’s a quick overview of the most common signs that you will find around you in the lab.

Flammable: it ignites

This is probably one of those self-explanatory signs – chemicals labeled with this are flammable and you should store them accordingly. Some laboratories have separate storage facilities for such chemicals e.g. in our lab we have special security storage cabinets outside the lab for storing the large bottles.

When you use such chemicals make sure you keep them away from any oxidizing substances, flames or sparks. You should also wear eye protection when working with highly flammable substances. Some examples of flammable chemicals we regularly use are ethanol and isopropanol for plasmid preparation.


Oxidizing agents: I give Oxygen

These substances are responsible for removing an electron from another substrate and thus are known as one component involved in an oxidation-reduction reaction. You should be very careful involving them in chemical reactions (e.g. mixing them with another chemical) while preparing a solution.

Oxidizing agents usually transfer oxygen to another chemical substrate. In this way, they can provide oxygen to flammable substances to burn when used in lab. You should always store them separately from flammable substances! Oxidizing agents may also set you and your clothing on fire if you are not careful – so don’t forget your gloves, eye protection and lab coat as precautions.


Corrosive agents: I wear it away

They are strong chemicals that can corrode into your skin or any other substances. There are many chemicals in our daily laboratory life that belongs to this category.

Strong acid (sulfuric acid etc.) and strong alkali (sodium hydroxide etc.) solutions are both corrosive. The ?-mercaptoethanol you use for reducing the disulfide bonds of your protein before running a SDS page or the crystal violet dye you use for staining your bacteria are also corrosive (along with their other individual hazards). One drop of these corrosive substances can cause you serious eye damage! When working with corrosive substances you should use precaution – non-corrosive gloves, eye protection and lab coats are all musts.


Toxic: I poison

These are highly harmful substances and, in extreme cases, can even cause death if you swallow, inhale or absorb them through your skin.

Examples of toxic chemicals include the HCl you use for adjusting your buffer to the right pH and the universal pH indicator methyl orange. You should always use eye protection, gloves, and a face mask to prevent inhalation when working with toxic substances. And don’t forget: handle the chemical inside a fume cupboard.


Irritant: It bothers

These substances can irritate your eyes and skin causing itchiness, soreness, redness and blistering. Don’t mistake them for harmless either, they can also cause toxicity if you inhale or swallow them.

For example, the calcium chloride you use for making your competent cells and the SDS for your protein gels both are irritants. You should be careful while preparing solutions containing irritants and make sure you protect yourself properly.


Health hazard: It’s a risk

These chemicals can cause you serious health damage including reproductive toxicity, problems with your respiratory system, germ cell mutagenicity, carcinogenicity etc. Many of the chemicals that you are using carry such serious health hazards.

For example, ethidium bromide used in DNA agarose gels, is a mutagen. Phenol and Chloroform both belong to this category too – phenol is a reproductive toxin and its vapor is also corrosive to eyes, skin and the respiratory track. Acrylamide is carcinogenic and neurotoxic too! So make sure you use appropriate PPE – eye protection, nitrile gloves (for chloroform you need special 8 mil or heavier nitrile gloves), a lab coat and a face mask are all essential when you work with such substances.


Environmental hazards: Nature matters

These chemicals are potentially hazardous to the environment – if not properly disposed of, they can contaminate soil and water, and can be lethal for aquatic animals and trees. You should be very careful while disposing these substances!

For example, bromoform and phenol are environmental hazards. Before you start working with these chemicals in the lab, make sure you learn the rules for disposing of them when you are finished using them.


Explosives and compressed gas: I can blast

Explosives are not generally seen in your normal labs, compressed gas on the other hand is a fairly common sight e.g. CO2 cylinders in tissue culture. Gas cylinders and aerosol cans are compressed gases that should be treated with caution. Stocks of compressed gas cylinders are normally stored separately from the main lab in special safety cabinets.

explo    comp

Bio-hazards: Organism problem

This sign can be found on doors or trash cans of your lab, so that you are aware that you are entering an area in which biological material, such as cell lines, bacterial or human samples, are used, and also indicates where to discard waste associated with your organisms.

For example, cloning regions of interest into a plasmid using E.coli is a standard laboratory technique – imagine what could happen if we let all of these cloned bacteria free in our environment! Or worse – maybe you are working with contagious organisms; we could get in serious trouble if these organisms escape the lab. Protect yourself properly when working with such organisms, avoid any direct contact and make sure you know what bins you should be using for them.


Laser and ionizing radiation: I am harmful

These signs generally appear only in areas that you should get a fairly intensive safety introduction on before beginning work.

Lasers can harm your eyes causing severe injury; you should be well protected before entering labs that utilize lasers.

If you have to work with radiolabeled isotopess e.g. you want to run an EMSA, you generally have to check with your doctor first to check you’re in a fit condition to allow you to work in such a lab. Make sure you are fully informed about all the safety rules and the type of PPE you’re required to use in order to protect yourself and those you work with before your enter these labs.

las             radia

High voltage: I can electrify

Be it your PCR product or your expressed protein, you want to see whether or not it is the right product and the most common (and probably most cost effective) method of visualizing this is through running your product through a gel using an electric field. When using gel running apparatus, be careful! If you are not paying attention you can end up giving yourself an electric shock. You can find the high voltage sign in your gel electrophoresis apparatus, so don’t forget to switch off the main switch before your take your gel out of your running buffer.


Hot and cold warning: Temperature shock

Extreme temperatures are also a potential lab hazard that should not be ignored.

I think most labs have one electric plate or induction cooker for sterilizing small quantities of solutions, or for creating a supersaturated solution if you are struggling to dissolve something; some of these hot plates can reach temperatures of 450°C, so when you are using them be careful you don’t give yourself a nasty burn! At the other end of the spectrum, it is also important to understand the safety concerns associated with extreme cold temperatures; the -80°C freezer is the standard storage option for cDNA and glycerol stocks, not to mention how often you use liquid nitrogen to freeze you samples! Special cold-resistant PPE is required to use both the -80°C and liquid nitrogen facilities to avoid frostbite, so make sure you’re well informed before you make use of extreme cold temperatures.


While this list isn’t exhaustive, and you’ll have to look up the other warning signs present in your lab, there are a few general rules you can follow to keep yourself safe in the lab. It’s always best to wear:

  • a long sleeve lab coat (you can always fold your sleeves when you work in the laminar air flow bench);
  • full pants (yes, even in those hot summer days when your lab air condition is not working);
  • closed shoes;
  • eye protection.

Make sure you know what type of chemicals or hazards you will be working with and protect yourself accordingly – precaution is better than cure!