6 Essential Lab Safety Rules
How To Guide Oct 12, 2018 | by Ju Lin Tan, PhD
The laboratory is a place where ideas are conceptualized and materialized into novel discoveries. As the laboratory houses a vast array of complex equipment and dangerous chemicals, it is imperative for someone to prioritize safety measures when entering the facility. Laboratories are categorized into different biosafety levels according to the danger they pose – levels 1, 2, 3, and 4. Levels 1 and 2 are usually assigned to laboratories that work with agents that pose minimal to moderate hazards such as E. coli, B. subtilis, S. aureus and P. falciparum. Levels 3 and 4 are assigned to facilities that work with agents that pose serious hazards, that could be potentially lethal. These agents include M. tuberculosis, Ebola virus and Nipah virus.
Regardless of the biosafety level of the laboratories, it is important for a person to always ensure that safety comes first. This includes the use of appropriate personal protective equipment (PPE) as a bare minimum. You can always repeat an experiment but you will not be able to do so if you succumb to injuries. This guide outlines some of the precautions one can take to ensure safety in the laboratory.
General laboratory safety measures, settings and ergonomics
Before working in a laboratory, it is important for you to undergo proper training so that you are introduced to the general laboratory layout and the appropriate safety measures. The safety measures that are commonly used include putting on the appropriate protective personal equipment (PPE) - such as lab coats and gloves - testing the eye wash and showers intermittently, identifying where the spill kit, first aid kit and emergency exits are, whilst also familiarizing yourself with the fire exit route. On a related note, please refrain from drinking the distilled water from the sink regardless of how thirsty you are!
To ensure a conducive work environment, the laboratory floor should also be kept neat and clear of obstacles; avoid putting boxes on the floor as they can cause injuries to passers-by. Similarly, do clean up loose tips or microfuge tips from the floor because you might accidentally step on them and slip. Also, avoid putting glassware at the outer corner of the laboratory bench as they can easily be toppled over - broken glassware will produce glass shards which can cause injury to a person.
The safety measure that is less spoken about is the proper practice of laboratory ergonomics. Prolonged standing can hurt your back, therefore it is important for you to sit comfortably when preparing a lot of samples in one sitting. For example, when you are preparing samples in several 96-well plates, do sit down and adjust your chair while maintaining an upright, supported position. Similarly, when carrying heavy rotors for the large-capacity centrifuges, bend your knees to carry them so that you do not have a 10kg item exerting its force on your back; in this instance it is also recommended to wear steel toe-capped boots. Remember to have some water breaks during your laboratory work because you have to stay hydrated regardless of how busy your day is.
Handling chemicals and preparing reagents
After getting cozy in the laboratory, you are now ready to perform some experiments. Before that, you must prepare laboratory solutions which will provide the optimum conditions for specific biochemical reactions and cell growth. For example, when working with ATP-dependent proteins, the reagent should typically contain sodium or potassium chloride (for maintenance of protein function), DTT (to prevent the formation of disulfide bonds), glycerol (to prevent protein aggregation) and magnesium (as a cofactor of ATP hydrolysis). It is therefore important for you to understand the potential dangers associated with handling these chemicals.
Go through the Materials Safety Data Sheet (MSDS) to understand what type of hazard the chemicals pose. These chemicals can be toxic (e.g: dimethyl sulfoxide), carcinogenic (e.g: ethidium bromide), flammable (e.g: methanol), or corrosive (e.g: hydrochloric acid). It is important for you to know how to store these chemicals because careless storage is dangerous; safety cabinets are provided for the storage of flammable, corrosive or toxic chemicals. You also need to know what should be done if you come into contact with these chemicals. For example, if you come into contact with acrylamide, a neurotoxin, you have to wash the affected areas with running water for at least 15 minutes.
Now, let’s put on some gloves, get some Schott bottles and prepare laboratory solutions! Always remember the properties of each chemical that you are working with. Take Coomassie Brilliant Blue or Western Blot destain solution for example. When preparing these solutions, you will have to handle methanol, an easily combustible organic chemical. As this chemical releases toxic fumes, it is advisable that you prepare methanol-containing solutions in a fume hood. When using SDS powder to make a stock solution, remember to wear a face mask as the SDS powder is very volatile and toxic.
After making your reagents, clean up the work bench and weighing machine. This will remove residual chemicals that may endanger your colleagues’ health. Always label your bottles to let your colleagues know all the contents of the reagents: as a minimum include the concentration of each chemical in the solution, the date when the solution was made, an expiry date and your name.
Handling biological material (e.g. cells and mice)
Often when it comes to working in drug discovery, you will have to generate recombinant proteins in bacterial or human cells for functional studies using biochemical assays. When handling bacterial culture and working with human cell culture, always ensure you wear gloves and try to tuck the lab coat sleeves into your gloves; this will fully protect your wrists and avoid knocking the cell culture over by accident. When working with viruses (e.g. preparation of viruses and during viral transduction), it is advisable for you to wear an extra layer of gloves. It is also important for you to treat the fume hood with UV light for at least 30 minutes after use. This will ensure that all residual viruses or viral particles in the hood are killed, before letting another person use the hood.
To obtain cells for DNA extraction or to examine endogenous levels of specific proteins, cells are usually collected through centrifugation. After collecting the cell pellets, do not discard the supernatant into the sink. Instead, transfer the supernatant into another container and autoclave this or treat it with bleach to ensure that all remaining cells in the supernatant are killed. Then, you can discard the treated supernatant into the sink. Likewise, treat the used tissue culture plates with bleach prior to disposing of them in the biohazard bin.
If you need to work with mouse models, do attend proper training to understand how to handle a mouse properly. Avoid agitating the mouse as this action might cause it to scratch or bite you. If you are snipping the tail of the mouse for genotyping studies, always ensure that the work surface is sterilized after you have completed the task. When working with biological material including cells, always sterilize your work surface with 80 % (v/v) ethanol/water.
Handling laboratory equipment
To carry out an experiment, it is important for you to understand the standard operating procedure (SOP) of each piece of equipment to ensure you know how they work. For example, it is important to confirm that a centrifuge is balanced before starting the spin. An imbalanced centrifuge can lead to strong vibrations which may lead to a rotor crash or cause an injury to the user. Take extra precautionary steps when you are using a large-capacity centrifuge.
When removing hot glassware from laboratory ovens or the autoclave machine, it is important for you to wear a thick pair of gloves. Thick gloves are also required when you are removing a conical flask containing hot, melted agarose. Moreover, remember to point the spout of the conical flask away from your face. When using the sonicator to lyse cells or disrupt materials for a prolonged period, ensure that you use hearing protection because the sound waves generated by the sonicator can damage your ears.
Experimental work – where many things can go wrong
Got your reagents and samples ready without hurting yourself? Congratulations! Now, you are ready to perform some ground-breaking experiments. However, here are some things to look out for when you are working with your samples. When you are discarding used pipette tips into biohazard bins, please ensure that you do so carefully. You don’t want to end up shooting contaminated tips to your colleagues sitting opposite you!
When you are carrying out bacterial inoculation, please ensure that you don’t burn yourself with the flame of the Bunsen burner, or with the hot agar plate spreader. Before decontaminating the spreader in a beaker of alcohol, make sure that the alcohol is not absolute. Alcohol is a highly combustible chemical and if made wrongly, the alcohol will burn when it comes into contact with the hot spreader. If this happens, you need to calm down and put on your thinking cap – “how can I stop the flame?”. Remember, combustion occurs when there is a supply of oxygen. What you can do here is quickly use some aluminum foil to cover the beaker to cut off the oxygen supply. By doing so, you will stop the flame.
When visualizing a DNA gel using UV light, ensure that your wrists are protected by the sleeves of your lab coat. Moreover, ensure that your eyes are protected from the UV rays. Please be careful when you are excising a band from the DNA gel using a sharp scalpel, as you can easily cut yourself by accident. Unlike DNA samples, protein samples have to be boiled prior to analysis using SDS- PAGE. If necessary, use a pair of tweezers to remove your protein samples from the heating block (which can reach up to 100∞C) to avoid getting your fingers burned. For both DNA and protein analysis, always ensure that the running buffers are made correctly to avoid unnecessary overheating of the gel-running apparatus during electrophoresis.
For the purpose of long-term storage, samples can be snap-frozen in liquid nitrogen. Firstly, you will have to dispense some liquid nitrogen from the dewar into a container, but do not fill it up to the brim. Overfilling the container with liquid nitrogen is dangerous especially when you are transporting it from one room to another. If transporting a huge amount of liquid nitrogen using the laboratory lift, put up a sign to stop other people from entering the lift. This is because liquid nitrogen can reduce the oxygen concentration in the air, acting as an asphyxiation agent. When you have snap-frozen your samples, do not pick them up with your gloves as your fingers might suffer from cold-burns. Instead, use a plastic scoop to do so.
When thawing samples from the -80°C freezer, there is a possibility that the lid of a microfuge tube will snap off due to a sudden change of pressure inside the tube. Please be careful and wear a pair of safety goggles as the lid might injure your eyes. If the sample contains radioactive material, extra precautionary steps have to be taken. If you dropped this sample by accident, there will be a radioactive spill which is highly hazardous. If this happens, you will have to contain the work area and report the incident to the radiation safety officer immediately.
After a long successful day in the laboratory, you must clean your bench and dispose of chemicals or microfuge tubes that you don’t need. Broken glassware has to be discarded in a designated bin that is strictly for glass waste. Biological waste such as agar plates, tissue culture plates, cell pellets, and used gloves must be discarded into biohazard bags. Please ensure that you line the bins with two layers of biohazard bags to avoid spilling of biological material.
Solutions containing organic chemical should be disposed into a designated bottle and sent to the safety officer for further disposal. Scalpels and needles are sharp items and they have to be discarded into biohazard cans. Remember to tightly seal the lid of the biohazard cans to prevent your waste from spilling out. Do not discard sharp items into biohazard bags because these items can pierce through soft materials, causing an injury to the person handling the bags.
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