Home Lab Safety

avoiding and surviving the unexpected…

© 2014 by KV5R. Rev. June 1, 2014.


And there we were, with that brand-new neato microscope and a bunch of little bottles of chemicals and stains and needles and micro-tools and glassware, just waiting for the chance to do something cool, like getting the perfect picture of some clueless critter munching on… well, whatever it is they munch on. Then something completely unexpected happens, and it rapidly escalates into a disaster.

I cannot accept any responsibility or liability for your accidents, but this series would not be complete without at least a basic safety awareness section. First of all, I detest the busybody nanny-state and their hysterical fanaticism, invading every aspect of our lives. But we’re talking about a home hobby lab here, not a regulated workplace or even a school setting. If you want to store bottles of acetone and xylene in your oven, and keep live bacteria cultures in your refrigerator, you certainly can—but those would be pretty stupid things to do, and no one would. But alas, it’s usually the not-so-obvious things that cause the problems…

The microscopy lab does have some hazards, but no more so than the garage or workshop, where you might poison yourself or burn the house down while refinishing a piece of furniture or welding the lawnmower. The trick is to become aware of lab hazards and develop habits and skills to avoid them.

Lab Safety

This is the part we all like to skip—usually written by some legal department for imaginary numbskulls that can’t walk without tripping over a nuclear weapon. But let’s go ahead and make sure we have some awareness and common-sense in mind before we go inhaling some carcinogenic chemical or burning the house down. “Not me!” Oh yes, even you. It happens. The person who thinks “it won’t happen to me” is the most likely candidate for the unexpected. Accidents are, by their very nature, unexpected. If you think it can’t happen to you, you probably shouldn’t even drive, saw lumber, or fry fish—much less run a home science lab.

There are at least three areas of potential danger in the amateur microscopy lab:

  • Physical — getting cut, burned, etc.; these sudden pains may cause us to knock things over and escalate the disaster.
  • Chemical — acids, alkalis, and flammable solvents; these also cause panic reactions that can escalate the disaster.
  • Biological — The stuff in pond water probably won’t hurt you, but you really don’t want those little guys in your blood or stomach! And if you’re not thinking about it, bacteria and protists on your hands can easily end up in your mouth, nose, and eyes. We all frequently touch our faces.

If you have children at home then you have a special responsibility to show them that conscious safety procedures are an integral part of the hobby, and must be followed without exception. Okay, so you have trained them and you can trust them. But what happens when they bring their little friends over and they want to play in the microscopy lab? Are they well-trained enough to control their untrained friends? Do they know how to respond to an emergency if no adults are present?

Any professional lab tech will tell you that they are required to rigidly follow safety protocols at all times; failure to do so is grounds for immediate termination—of one’s job if lucky, or of a life if not so lucky. Lab workers, like electricians, surgeons, and astronauts, learn to coreograph their movements. When manipulating dangerous things, any movement without prior conscious thinking and planning is just asking for an unexpected event that results in damage, injury, or disaster.

Microscopy labs require careful and knowledgeable handling of corrosive, flammable, and maybe even carcinogenic chemicals, along with various biological hazards. The CDC, NIH, and others provide free on-line e-books about lab safety procedures, and I do recommend that you at least browse some of them (several are linked below). You will soon learn that cross-flow ventilation (e.g, fans in windows), lab coat, chemical gloves, and eye protection are just darn good ideas that you shouldn’t skip. Think: what would you do if you slashed your finger while handling bacteria-infested pond water? Or, will you just fire up the spirit lamp to melt some wax, while cleaning slides with acetone? What would you tell the firemen if your burning lab contains liter bottles of acetone, methanol, and xylene? How fast can you run to the shower, blinded, with acid in your eyes? It does deserve some forethought…

Learn to plan for (or rather, against) unexpected disasters, and plan each movement accordingly. That’s just good common sense. Just because something is done in the comfort of the informal home environment doesn’t mean it isn’t dangerous. But that doesn’t mean you can’t handle it safely, if you keep your wits at all times. For example, don’t put acetone on a tissue paper then light a cigarette—that’s just asking for trouble! But it’s so easy to do, when we aren’t actively thinking about it.

Lab safety is simply the development of habits, all prefaced by a conscious “what if…?” prior to each and every potentially dangerous action. Once you develop that mind-set, your opportunities for unexpected incidents and disasters will be greatly reduced.


Here are a few things to get you started thinking about potential hazards and ways to avoid them. Obviously this is not a complete list, and you may want write your own lab safety checklist.

Physical Hazards

Lots of things in labs are just plain sharp! Indeed, they are called “sharps.” They include syringes, needles, lancets, blades, broken glass, and contaminated glassware. Sectioning plant stems with razor blades, using needles, and even mis-handing coverslips can easily result in cuts and punctures, exposing us to biological infections. Learn how to frequently wash hands and sterilize instruments. Use latex gloves. Scrub even the smallest cuts with soap and water, then alcohol. Use an Xacto knife or scalpel (something with a handle) instead of a utility razor blade. Work and move carefully and deliberately. Keep all sharp instruments and glass locked away from children when not actually in-use.

The disposal of sharps is regulated by law, to protect waste disposal workers from hazards. They must be placed in rigid plastic sharps containers and properly labeled. When full, the whole container is sealed and discarded. You can buy them on-line; the small ones are commonly used by insulin users for syringes and lancets, and should last the home-microscopy-lab user a long time. The Kendall 1-quart biohazard sharps container is about $5 (click the image to see).

Sprit lamps are very handy when you need to heat-fix a slide or melt some sealant. But an alcohol flame contains almost no carbon, and is therefore almost invisible. It’s quite easy to get a little burn before you know it. Also, any open flame in the lab must always be extinguished before you dispense even a drop of alcohol, acetone, xylene, or any other flammable chemical.

Ingestion, inhalation, and absorption — both volatile chemicals and biological samples must be controlled to eliminate any possibility of chemical injuries and infections. Remember that all chemicals, stains, glass, sharps, and bio-samples must be locked up if you have young children. They see you “playing” with all those pretty little things and they want to emulate you and join the fun. This must never happen without your direct supervision. If they spill a bottle of acetone, there will be a highly flammable (possibly explosive) cloud of vapor within a few seconds. Inhalation of such volatile chemicals may cause unconsciousness and death. Ingestion of corrosives will cause choking, extreme pain, stomach bleeding, and possibly permanent injuries or death. Bio samples that are spilled will dry up and allow pathogens to float in the air and be inhaled. Spilling a stain will surely ruin your carpet, and leave you or your child purple for a long time. Coverslips are almost invisible; if you drop one on the floor you probably won’t find it until someone steps on it, cuts a foot, and gets an infection. Always keep track of how many coverslips you have out of their box and on the desk.

Think of other things you might add to this category.

Chemical Hazards

Mind Control

As I state in my article on soaping safety, many people have an irrational fear and even a hysterical hatred of all “chemicals,” a mind-set called chemophobia, caused by brainwashing and ignorance. This irrational fear may lead to accidents—we must be calm and rational to be careful. The universe is made of chemicals; most are beneficial, some (both natural and synthetic) are dangerous to life, and many are essential to life but dangerous at high concentrations. For example, the immune system’s NK cells actually make bleach (sodium hypochlorite) to kill invaders, but we certainly wouldn’t drink 6% laundry bleach for an infection! But we might use a 1% solution to sterilize a bio-contaminated surface or container. Like fire, chemicals must be understood and handled properly, but not feared. Fear is never your friend! An irrational mind-set leads to irrational actions.


Most acids and bases (corrosives) used in the lab are very diluted, but we may also have stocks of concentrated stuff, such as glacial acetic acid and sodium hydroxide (caustic soda, lye). These are very dangerous and must be handled with the greatest possible care. When diluting, never add water to a strong corrosive — always add the strong corrosive to the water, little by little, and work in a wet basin (the kitchen sink), with running water. Use gloves, eye protection, and cross-ventilation. If you get a corrosive on your skin, you must flood it with water immediately. Strong corrosives are probably the greatest danger we will encounter in the lab, because they are highly reactive, exothermic (heat-producing) when being diluted, may produce choking fumes, and may be dropped, splashed, or spilled, causing both panic and rapid injuries. Again: don’t make dilutions or potentially reactive mixtures on your lab table, make them in a wet basin (the sink) with the water running, with gloves, with ventilation, and with eye protection. And don’t go carrying it through the house until the reaction has stopped and it has cooled to room temperature. Even then, cap it and rinse it before removing it from the sink. Use a polyethylene bottle, not a glass jar. You may trip over a toy, but that’s no reason to splash the kid with 30% caustic or acid. There is no excuse for any such preventable accident! It’s so easy to take one little extra step and eliminate the possibility of disaster.

Even mild corrosives pose some danger. You don’t know you dropped a drop of 5% hydrochloric acid on your pants until sometime later, when you discover an itchy spot and a hole in your pants. Mild acids can be neutralized with baking soda, and mild bases can be neutralized with vinegar. But if it’s stronger than a few percent, neutralization may be exothermic enough to burn you. In any case, skin contact with a corrosive requires flushing with water, ASAP, followed by neutralization with a mild chemical having an opposite pH potential. For example, most housewives know that getting laundry bleach on your hands makes them feel slimy, and that applying vinegar instantly restores the hands to normal. This is because chlorine bleach contains a little caustic soda (sodium hydroxide, a byproduct of manufacture), which is basic (alkaline), and the 5% acetic acid in vinegar neutralizes it.

Never allow corrosives to contact aluminum. For example, sodium hydroxide and aluminum react and make hydrogen and carbon monoxide! Always use borosilicate glass (lab-grade Pyrex) or plastics approved for corrosives (usually polyethylene), or stainless steel. Remember that some reactions get hot so fast that they will shatter regular glass jars.


Never mix any two or more chemicals without knowing the potential for reactivity. Acids and bases are opposites that will react, sometimes violently, instantly rising to boiling temperature and flashing into the face and eyes. Other chemicals may react quietly, but produce a deadly gas. Never mix any chemicals without researching them first and following a written protocol. Even something as simple as making a dilution of sodium hydroxide with water will be exothermic, get boiling hot, and produce choking caustic fumes.

Volatile Solvents

Other chemical hazards include several common solvents, which are volatile, flammable, easily absorbed by skin, and a few are known carcinogens.

  1. Keep your bulk chemical containers in a locked, ventilated, outdoor tool shed, or similar safe location.
  2. Keep only small quantities in the lab, no more than a 30mL bottle.
  3. Mount a dry chemical fire extinguisher nearby, between your lab and the exit. The small disposable ones are not expensive, and someday may save the day.
  4. Always extinguish flame (including cigarettes) before using any flammable chemical.
  5. Use cross-ventilation, such as a fan in a nearby open window.
  6. Use gloves, but remember that some solvents will melt latex gloves. Chemical gloves should always be used when handling organic hydrocarbon solvents like xylene.

Think! Where would you want your jugs and bottles of flammable chemicals if the house was on fire? You can buy a small outdoor tool shed, for under $200. Put it at the far end of the back yard and keep your flammables in it, including your lawnmower gas can and your paint thinner. Just make sure it’s always locked. Remember that thieves look for chemicals to make dope, and children like to play with fire.

Keep in mind that stains, fixatives, and mountants may contain hazardous chemicals (usually solvents). Be sure to read the MSDS for each one you buy and use.

The above are just a few examples to get you thinking. Think of other things you might add to this category.

Biological Hazards

Let’s face it: people have been swimming and bathing in, and even drinking, microbe-infested water for millions of years, and yet we’re still here. We can thank the immune system for that. On the other hand, millions are dieing in the third-world for simple lack of a few PPM of chlorine in their drinking water. The fact is, we never know what’s in standing pond water, yet as microscopists we collect it, bring it in the house, and handle it. Let’s learn some basic aseptic practices.

Bacteria are not invincible. It’s actually easy to remove them from a smooth surface, with just running water and a little rubbing. But it’s more difficult to remove them from rough surfaces like our hands. The problem is that when we are routinely handling live specimen samples, we are also unconsciously rubbing tired eyes, itchy nose, and even the mouth. Not a good idea! Wearing latex gloves is good, but we still need to rub and scratch. It takes a while, but if you just keep it up for a few sessions, you can develop the habit of never touching your face until you’ve washed your hands with soap. Keep a dry washcloth handy for wiping the face or scratching an itch.

Everything that touches pond water should be washed with soap when done with the sample, including slides and slips, jars, pipettes, and test tubes. The prep area should be wiped down with a mild bleach solution. As with chemicals, never set a sample bottle or jar down without first capping it. They are just too easy to knock over and spill on the rug, where they dry up and float away. Letting pond water dry up will kill many critters, but some protists, bacteria, and viruses may just float away and then become active when re-hydrated, like when you inhale them into nose, mouth, and lungs. Indeed, we all inhale and ingest millions of bacteria every day, and most are harmless. But some are pathogens, so keep the samples under control, and keep your hands, instruments, and work area clean and disinfected.

According to what I’ve read, the greatest bio-hazards in the microscopy lab come from culturing bacteria and molds, and from blood and other bodily fluids. Handle these just like the pros do, using well-established aseptic practices. There are many good sources on-line, free for the reading. As a minimum, you may want to start with one of the many good lab-safety checklists. Practially every university has one on-line.

A pressure cooker makes an excellent autoclave, and the smaller sizes are inexpensive (the Preso 4-quart pressure cooker is under $26). Be sure to read and follow the instructions for autoclaving in a pressure cooker. Typically, it will specify 15 PSI for 15 minutes, and the objects to be sterilized should be placed on a low metal rack just above the boiling water. But any autoclave, including a pressure cooker, poses its own dangers, including severe burns and possible explosions, so never use a pressure cooker without fully understanding the dangers and carefully following the instructions.

After a while, you may find that following safety protocols is yet another interesting aspect of the hobby. Think of other things you might add to this category.


Here’s a 360-page PDF book, free from the National Academies Press: Prudent Practices in the Laboratory (2011). Mostly about chemical hazards but some on biosafety, too.

Here’s a 170-page PDF book, free from the World Health Organization: Laboratory Biosafety Manual (2004).

The Centers for Disease Control (CDC) has several free Laboratory training books - CDC L Index

The CDC also provides on-line lab training certificate courses - CDC Lab Training Courses

Next, we’ll start having some fun! We’ll collect a sample, make a wet mount, and take a look at some critters.


Leave a Reply

Your email address will not be published. Required fields are marked *