An Irreverent Guide to

Safety in the Chemistry Laboratory



Tom Lyons Fisher


Roy D. Nagle
















Drying Oven






Fume Hood








Ice Machine


Lab Rules

























DISCLAIMER: This manual is an attempt to get your attention about safety and waste management. It's not comprehensive and it's not endorsed by NSF, but we hope it's something you'll read. Any safety manual is a constantly changing document. Your suggestions are eagerly sought.


Tom Lyons Fisher

(814) 641-3563



Roy D. Nagle

(814) 641-3555


Juniata College



Huntingdon, PA, USA





ACKNOWLEDGEMENT: This project was funded by a curriculum grant from the National Science Foundation.



A flight instructor was reviewing safety procedures with a student pilot: "If you do have to make an emergency landing, try to put the plane between two trees. That slows you down gently by breaking off the wings." Sure enough, 3 weeks later, the student pilot had an engine problem and couldn't make it back to the airport. But he remembered his instructor's advice, and put it right between two trees. It totaled the plane, but he walked away unhurt. That was the good news. The bad news was he was flying over Kansas, so those were the only two trees in the county!
Moral: No Set of Rules Can Cover Every Situation; Use Your Common Sense!

Even though the laws and regulations and rules which govern safety and waste management cover many volumes, this manual is short because you need to read it!  It attempts to tell you what you need to know now, so it's deliberately uncomprehensive. That means that it's your responsibility to find out the correct procedure for what you want to do.  Here's where to check:

Above all, you must realize the responsibility for your safety and the planet's health rests with YOU. You need to be alert for dangerous situations and try to correct them...


A meticulous graduate student was an expert at sodium metal reductions. (She'd done 21 of them already.) These reductions concluded by slowly and carefully destroying the excess sodium in ethanol, then dumping the waste down the drain. The 22nd time not all of the sodium got destroyed before the flammable waste mixture was poured into the wet sink. She was wearing goggles. But she no longer has earlobes.
Moral: Constant vigilance is the price of safety.

A laboratory is anyplace where there is a greater danger than listening to a history lecture in Good Hall. So a laboratory isn't a place as much as it is an activity. When you enter a laboratory, you're no longer in a household environment. The materials are not on the GRAS (Generally Regarded As Safe) list, the instruments are all handmade, and the personnel are presumed to be knowledgeable, careful, and mature. As painful as it might be, you need to be thinking all the time.




For your own safety, you should constantly be thinking:

"What if...?",


and for the Earth's continued good health, you should be thinking:

"Cradle to grave".






General Lab Rules


Juniata's Chemical Hygiene Plan requires that you wear adequate eye protection while in a chemistry laboratory! Ordinary glasses, even if they're shatterproof, don't provide side protection and are therefore inadequate. Choose an even greater level of protection (goggles, faceshield) if splattering, implosion, etc. is a possibility.

Because of AIDS and other transmissible diseases, no human bodily fluids (blood, saliva, urine, etc.) are permitted in lab.

No food is permitted in any laboratory (except when it is the sample for an experiment and will not be eaten subsequently). Food includes soft drinks, gum, Popsicles, chewing tobacco, and cosmetics, too! Don't even bring unopened soft drink cans or sealed containers of food into the lab.

Mary, a lab technician in a research hospital, was told that the coffee was in a beaker on a hotplate in the lab across the hall. She went over, poured herself a cup, and went into cardiac arrest. Fortunately, 5 physicians heard her hit the floor; unfortunately, she died in the elevator on the way to the ICU. (The coffee was on the other side of the bench; the alkaloid digestion was on this side.)
Moral: Don't eat, drink, or be Mary in the lab

Never put anything in your mouth while in a lab. This includes pipets, hairpins, and tubing as well as food.

Smoking isn't allowed for several reasons: It causes cancer in the smoker and possibly innocent bystanders, and the act of lighting up could cause a fire or explosion.

Know the location of the nearest safety devices: fire extinguisher, safety shower, eye wash, telephone, and exits.


So why are you carrying a bottle of sulfuric acid in through the hall during a class change? Why not wait until there's less traffic and fewer people would be injured if you dropped it?

If you simply can't decide what to wear to lab, here are a few fashion rules: no dangling jewelry or fabrics that might get caught in centrifuges or pumps or dragged through chemicals; no open-toed shoes or shorts; and if you have long hair, please fasten it.

Interpreting an MSDS (Material Safety Data Sheet): Don't panic! Chemical manufacturers are understandably leery about getting sued, so they protect their behinds by overstating the danger of their products. (To get some perspective on this, read the data sheets for water, sugar, or salt!) So you've got to read between the lines. (But please read the pertinent MSDS for NaCl before taking them with a grain of salt! A little OSHA humor there.) Although the MSDS format is not yet standardized, it must contain this information:

Learn to glance at the objective measures of danger such as the flammability and TLV rather than the prose to evaluate the danger because lawyers are only permitted to choose the words, not the numbers, on the MSDS.

Planning an experiment: Use the "What if...?" (Worst Possible Case Method) Here's some questions you should ask before carrying out any lab procedure:

What if...

Got the idea? Of course you'll get much better at creating these scenarios with experience…

Don't work alone in a laboratory. Someone must be within ear-shot of you at all times! The "partner" who you've convinced to trudge over to the Science Center with you this evening shouldn't then go to the Computer Center "for just a few minutes".

Good labkeeping: Keeping the lab clean and orderly has lots of advantages. Glassware is easier to clean if the gunk doesn't have time to coagulate. If the benches are free of extraneous stuff, cleaning up a spill is much less time-consuming. If you keep the floors free of spills (including ice!), there's less likely to be an accident.

A careless student, who didn't believe good labkeeping was important, performed an experiment in which he weighed out NaOH pellets. That evening when he removed his socks he found that a pellet had eaten through to his heel bone. He was hospitalized for 6 weeks. (Strong bases deaden nerves.)
Moral: It's important to keep track of the chemicals you use.

Unattended operation of equipment: As soon as you turn your back, let alone leave the building, whatever you've left running will go awry. This is The Most-proven Law in Science. You need the advice of a person who has done graduate work in a lab before you even think of leaving an experiment on its own. You and your advisor need to play the "What if...? game very seriously in order to minimize the likelihood or effect of any disaster. What happens if the cooling water in the condenser stops? (Regular water faucets are designed to slowly close if left on a long time.) Where will the water go if that hose breaks? What will happen if the power goes off? What will happen if it comes back on?

Because staring into the beam of a high-powered laser can cause permanent blindness, you're naturally more careful around such exotic equipment. It's often the ordinary equipment that you have to watch out for. Perhaps the device most likely to injure you is...the ice machine! Yep! It's almost impossible to avoid spilling ice on the floor when you're scooping it; and the ice is nearly invisible and slick, so the next unwary person is likely to end up end up. Some other equipment that can be dangerous: centrifuge, gas cylinder, drying oven, vacuum pump, Dewar flask, uv lamp, Variac.

Students "Katy" and "Penelope" arranged to come in on Saturday morning to make up a buffer experiment. The instructor unlocked the lab, got the students started, and returned to his office believing that buffer preparation was reasonably safe… Soon Penelope appeared at the instructor's door and said "Katy cut herself and she's bleeding into the sink." By the time the instructor got to the scene, Katy had managed to cover the bottom of the sink with blood from the palm of her hand. Seven stitches, an inch-long scar, and a little physical therapy left Katy with almost full use of her hand, but she'll never be a concert pianist. Although Katy doesn't know exactly what happened, it appears she pushed down on the stopper of a large volumetric flask hard enough to break the neck of the flask and force the jagged edge through her hand, severing a nerve.
Moral: Anything can be dangerous.





All glove materials are porous to some chemicals; surgical gloves and Rubbermaid dishwashing gloves are porous to lots of stuff.  Check the MSDS for compatibility data.


A drying oven don't get no respect because it's so commonplace. But using it can be dangerous. For one thing an oven is usually hot. (Any questions so far?) If your bare hand happens to touch part of the oven while you're reaching in for something, your reflexive response may knock chemicals onto the hot coils or break a piece of glassware whose jagged edge will rake across your hand as you hastily withdraw it. If that isn't scary enough, you could rinse your glassware with acetone and then place it in the oven. The next time the oven heater cycles on, the spark from the electrical contact will ignite the acetone and hurl the oven across the room. You can get the same effect by storing flammable solvents in an ordinary (not labeled "FLAMMABLES or EXPLOSION PROOF") refrigerator because the electrical contacts are inside on these appliances, too. Lastly, but not leastly, there's a really subtle danger from drying ovens. You should never use a mercury thermometer to monitor oven temperature by poking it through the oven roof. It's very easy to snap them off when utilizing the top shelf. What happens to the mercury? It drops onto the hot coils and now you've really got a toxic air pollution problem.


Fume hoods are great if used properly, but many students don't realize that hoods have limitations which are likely to be encountered in everyday use. The recommended air flow for standard lab procedures is 100 feet per minute. But some of our hoods will produce that only if the sash is lowered to align the arrows at the "SAFE FLOW" position. Even then, if an adjacent hood shares the same fan, it must be at the "SAFE FLOW" position as well. Also, keep in mind that the 100 fpm criterion is an average over time. If someone shuts the door to the lab or the wind pattern outside abruptly changes, or you move a large object in or out of the hood, there will be a momentary flow of air (and whatever is with it) toward you. Also remember that the hood window cannot protect you from an explosion; there's just so much tempered glass can withstand. So if there's the possibility of an explosion, keep your facemask on even when the hood sash is down. And never put your head inside the hood!

USING A DEWAR FLASK ("Thermos bottle"):



A Dewar flask consists of thin, stressed glass enclosing a high vacuum. You can work with these things for years until suddenly one day the wrong "dink" will produce thousands of high-velocity glass shards. You'd better have your faceshield on because there are no "glass magnets" for the surgeon to use to remove the shards from your eyes. The more modern Thermos-type beverage coolers which use styrofoam as the insulator are much safer (but perhaps less chemically resistant). If it's feasible, replace the classic glass Dewar with the styrofoam type; if not, at least wrap the glass with electrical tape.


Do you really need to? Modern labs seldom use these. If you must, make sure there are no exposed flammable liquids in the room.


A 4.0 GPA chemistry major was performing an ether extraction in Organic Lab I, so she had an array of ether-filled beakers on her bench. The next operation required a steam bath which she attempted to heat by firing up her Bunsen burner. All five of the beakers immediately ignited. In a misguided effort to shut off the burner, she jerked the burner tubing from the gas supply nozzle. Since this gas was now unregulated, it produced an even bigger flame pointing directly at her. She panicked, and using her forearm, swept all of the gently-burning beakers onto the floor where they broke, allowing the ether to spread into a thin film and producing a spectacular pool of fire.
Although there were an even number of students in Organic Lab II, Miss 4.0 never could find a partner…
Moral: Common sense and a cool head are safer than a high GPA.





A typical gas regulator looks something like Mickey Mouse with the two ears being the gages. Sometimes Mickey has a goiter called the needle valve which is used to control very low flowrates. By the way, the needle valve should never be tightened, that ruins the needle. Instead use the regulator valve and the tank valve (not shown) to shut off the gas. The regulator valve should be "backed out" (turned counter clockwise) to shut off the gas. (If you want to make sure that the valve is off, unscrew it until it drops into your hand; just don't ding the threads.) Only then is it safe to slowly open the tank valve (a quarter turn counter clockwise is generally enough) while watching the high pressure gage. Adjust the regulator valve (clockwise) to obtain the correct pressure.

A gas cylinder can become a rocket if the (relatively weak) main valve fails. There are stories of cylinders on the loose going through several concrete walls while simultaneously venting large amounts of toxic or flammable gas. If you don't want this to happen while you're around, make sure the cylinder is properly anchored (usually with a bench strap) while it's being used or stored.

When moving the cylinder:

A welder working in a warehouse somewhere in central Pennsylvania failed to strap his acetylene cylinder. It tipped over, knocking off the main valve and turning the tank into an unguided missile which careened around the warehouse spewing toxic, flammable gas. It finally lodged in a steel girder rafter (3 stories above the floor) with such impact that it was left there as a warning.
Moral: Treat compressed gasses with respect.


Only a "flammables" or "explosion proof" refrigerator is appropriate for storing chemicals, and even then the chemicals must be in containers which prevent the escape of vapor. By the way, the designation "explosion proof" doesn't mean that you can prevent things from exploding by placing them inside! Nor does it mean that the refrigerator is specially reinforced to withstand an explosion. Nope, all "explosion proof" means is that the wiring has been placed on the exterior of the refrigerator so that electrical arcing cannot cause an explosion.


What could be dangerous about an ice machine? Well, did the previous person spill at least one piece of ice? That ice is tough to spot and very slippery. Now suppose you not only slip on it (which is bad enough) but that you fall in such a way that the beaker you're carrying is under you… So an seemingly innocuous ice machine could plausibly cause a lethal injury. Assuming you've managed to avoid death so far, DON'T scoop the ice with your glass beaker! If it breaks, how are you going to locate the pieces? Of course some future "ice customer" will find the missing pieces, but you'd better be a Missing Person by then. PLEASE USE THE SCOOP! Oh, and please don't put laboratory ice in your drink!





This type of transformer is utilized for many routine laboratory operations such as controlling heating mantles, but it can be dangerous. That's because it is an autotransformer which means that it is connected directly to the AC power line (in contrast to the usual isolation transformer). So simultaneously touching a bare wire (or one with faulty insulation caused by solvents or abrasion) from the transformer and anything that's grounded would result in a possibly deadly shock.





Before applying a vacuum, inspect the glassware you'll be using. Is it designed for vacuum work? Does it have cracks or chips that would cause it to fail under stress? (Be sure to check round-bottom flasks for "star" cracks.) Don't expect ordinary glassware to withstand a vacuum. Remember that it's more important to distinguish between a big/small vacuum than a high/low vacuum. A high vacuum (say, 1.7 microtorr ) and a low vacuum (maybe 14 torr) are both a long way from 760 torr! It's more significant (and dangerous) that the lower vacuum is frequently present in much bigger containers, and therefore potentially much more lethal. In these situations, wear a faceshield and make sure your coworkers are protected by some sort of approved barrier (Plexiglas, tempered glass). You need to arrange to trap any vapors that will arise from your work. If you're using the building vacuum, any vapors you fail to trap will build up in the equipment room until a spark from the electrical panel ignites them. Subsequent reports from the science center will be fragmentary.

Question: If you hear a loud "MOOB", is that from an implosion?


Be sure that the samples you are spinning are balanced. Remove your dangling necklace, talisman, Soap on a Rope, necktie, or whatever so you won't be strangled. Don't open the cover. Don't try to brake the rotor by hand.


1) Read the label.

2) Know the hazards: read the MSDS which can be found in the MSDS binder in the laboratory or on the P: drive under BAClab or VLlab.

3) On the basis of the MSDS, decide whether you really are willing to take responsibility for the correct handling and disposal of this chemical.





4) After making the necessary preparations for its transport and storage, sign out the chemical.

Transport precautions:

Wait until the hall is relatively clear. (Not between classes!)

5) Return the unused portion of the chemical for restocking.

6) Dispose of the waste correctly.














Dry diethyl ether ("ether"), tetrahydrofuran ("THF"), and dioxan are frequently used as solvents. They are dangerous not only because they are flammable, but also because, over time, they can be converted to peroxides by exposure to atmospheric oxygen. Although there are methods (for example, starch-iodine paper) for testing for the presence of peroxides, it's far better to carefully dispose of any ether or epoxide that has exceeded its shelf life. Decalin also has the nasty habit of forming peroxides.












What to do in an EMERGENCY:



1) If it's a fire,




If clothing catches fire,













Waist Management: Rule #1: Minimize your intake.

Waste Management: Rule #1: Same as Waist Management. Not only does using less put less stress on the environment, but it's also a prudent safety precaution:


The explosive force of a reaction increases as the cube of its mass.



(For example, 3 times as much material = 27 times as much boom)


Every chemical container, no matter how briefly used or how innocuous the material, must be labeled ("Cradle-to-Grave"). If there isn't a convenient way of labeling in your lab, develop or demand one. The label should include: the correct chemical name (not "ethyl bromide" for "ethidium bromide") and concentration of every constituent. Sure it takes time to label every little thing, but consider what happens if you don't: At the end of the term, your prof finds a flask containing a substance with no label. Since everything must be accurately labeled before a clean-up crew will accept it for disposal, and it's a federal offense to dump or guess at the contents of an unknown, it must be subjected to exhaustive chemical analysis. The current minimum rate is $155; if the sample turns out to be something more complex than water, it could cost thousands of dollars to identify that little mixture of camphor in HCl/ethanol that you "were just going to use for a minute".

Everything you pour down the drain eventually makes it's way to Mount Union and beyond. If you have any friends there, remember what an environmentally-conscious poet once said:


The Solution



to Pollution



Ain't Dilution





Really Nasty Stuff: Here's a list of chemicals that you should treat with caution. This isn't the complete list, and items made the list for different reasons (some go boom, others cause cancer; check the MSDS). WHY ARE YOU USING THESE? Can't you find a substitute?



lead and compounds

car batteries, paints, gasoline, ceramic glazes

mercury and compounds

thermometers, electrodes

chromium and compounds

car bumpers (Those moving at high speed toward you are particularly dangerous.)


old lace








colorimetric assays


complexing agents

carbon disulfide

nmr solvent

dimethylformamide (DMF)


dimethylsulfoxide (DMSO)

nmr solvent

ethidium bromide

molecular biology

formaldehyde ("formalin")


osmium tetroxide

electron microscopy















CAS = Chemical Abstracts Service; issues a unique number for every known chemical

CHP = Chemical Hygiene Plan

DEP = Department of Environmental Protection (PA)

EPA = Environmental Protection Agency (federal)

IUPAC = International Union of Pure and Applied Chemistry; establishes the rules for naming chemicals

LD50 = Lethal Dose for 50% of the population

MSDS = Material Safety Data Sheet

OSHA = Occupational Safety and Health Administration (federal)

PEL = Permissible Exposure Limit

RCRA = Resource Conservation and Recovery Act

SARA = Superfund Amendments and Reauthorization Act

TLV = Threshold Limit Value



Important Phone Numbers


Emergency: 911

Campus Health Services: 641-3410

National Poison Control Center: 1 800-521-6110

Safety Officer: 3555


Famous Last Words



"Biology is safer (than Chemistry) because it doesn't use chemicals." Would you rather drink a microliter of methylene chloride or a virulent strain of E. coli? Which is scarier, a microgram of HIV or TNT?

"We don't need to wear goggles here because this isn't a laboratory." Anything that quacks like a lab and walks like a lab is a lab. A classroom which harbors leftover chemicals from a demonstration 3 years ago is a lab. The hall through which you carry your sample to the nmr is a lab.

"Chemicals are bad." Then you must be bad, since you're all chemicals.

"I'm just a visitor, so I don't need goggles." Thank goodness laboratories permit only smart explosions which know who to injure based on course enrollment.

A graduate student was running a reaction involving peroxides in a magnetically-stirred flask. Since peroxides are known to be temperamental, he placed the reaction behind a free-standing Plexiglas shield and went off to supervise an undergraduate organic lab. With about 120 bodies milling around the lab (Hey, this is a university!), it got quite warm in there, so the student stepped out into the hall so he could take off his goggles for minute to let them "de-fog". A good time to check on his peroxide reaction…Damn, the stirrer stalled… Just have to reach around this shield and turn the control up a bit…
The explosion was so violent that the casing of the magnetic stirrer molded itself around the interior mechanism. The student's Research Advisor, who carried him out to the loading dock to await the ambulance, said the student's face looked like a piece of hamburger. A top Japanese eye surgeon who happened to be on a speaking tour that day managed to remove enough glass fragments from the student's eyes so that the kid can tell the difference between day and night…
Moral: Being careful 99.9% of the time doesn't count.

"If anything goes wrong, I can always sue." Yes, and you just might win. But will $10,000,000 buy a new right eye?