You must enter into your notebook the hazard information and handling instructions for each hazardous compound that you will work with. This is straightforward, no exceptions requirement, but the question that eventually vexes every beginner is just how much hazard information, and precisely which handling instructions, to write down. For example, suppose you read the following information online, would it really be necessary to enter this into your notebook?
Water – hazardous, do not inhale
One way to approach this problem is to recognize that there is a spectrum of compounds and also a spectrum of lab hazards. Some are routine. Others are unusual and/or extreme. A compound, like water, that has been part of everyone’s entire lifetime, and is generally regarded as innocent, does not need to be listed among the hazardous compounds. Likewise, a truly routine hazard may not require special mention. But, aside from these special cases, all other potentially hazardous compounds and hazards must always be listed. So how can you tell these two types of situations apart?
We might consider what we mean by “routine.” Water is a “routine” substance in the sense that everyone has been working with water all their lives. Likewise, if a hazard (liquid water poses an inhalation hazard), and the procedures for dealing with it (do not inhale liquid water), are widely recognized and widely known, we can call it a “routine” hazard, but you need to be careful in making these decisions. What is routinely recognized by one person might not be recognized at all by another, and even lifelong acquaintances, like water and oxygen, can create hazards in the lab [NOTE]Organic chemists frequently work with so-called “water-sensitive” and “air-sensitive” compounds like sodium metal and methyl lithium. Compounds like these might instantly burst into flames, or even explode, when they come into contact with water and/or air (oxygen) so a notebook must list these hazards. However, the hazards would be listed with the water/air-sensitive compounds. “Water” and “air” do not need to be listed. Nevertheless, one must be extraordinarily cautious handling water and air around compounds like these.. Consider the following very realistic scenarios:
- You have been exploring the chemical behavior of various alcohols when treated with reagent ABC. You have performed dozens of experiments involving ABC and the same 5 or 6 alcohols for weeks now, varying concentrations, solvents, reaction times, and temperatures. You have read up on the hazards associated with ABC and the alcohols, and you have noted them several times now in your notebook. The work has become routine, and it feels pointless to record the hazard info anew with each experiment. Not only that, each time you open a bottle, mix chemicals, or dispose of waste, you know from habit exactly how to handle everything safely.
- Now let’s add one more wrinkle to scenario #1: you happen to share the lab with 2 labmates, and neither of them has worked with reagent ABC or your alcohols. How would they respond in an accident happens and you are not able to provide information to them? (Farfetched scenario? No! This could be a fire that is discovered when you are away from the lab, or it could be an accident that has incapacitated you in some way). Will your labmates (or the emergency first responders they call for help) be able to recognize, and deal with, the hazards that had become so ‘routine’ to you? Of course not.
Scenario #2 highlights several factors that you should remember at all times: 1) your lab work is not yours alone because others may (and eventually will) be called upon to deal with it at some point, 2) ‘routine’ is in the eye of the beholder because what is routine to you may not necessarily be routine to others, and 3) accidents and emergencies can take many forms (fire? inhaled vapors? splashes on the skin? cuts and bleeding?) so we need to be prepared for all of the hazards we might encounter. For these reasons, you should always err on the side of caution. Unless you can be certain that a hazard is truly “routine,” you must post the hazard information in your notebook, on chemical containers used for storage, and anywhere else in the lab that might be checked by labmates, visitors, and emergency responders.
The distinction between routine and extreme “must list” hazards can also be assessed by considering how the 3 ways in which chemical exposure is most likely to occur: eye contact, inhalation, and skin contact (putting a chemical in your mouth is absolutely forbidden, but if that occurs accidentally, treat this as a poisoning, call the Poison Center immediately and be prepared to render first aid).
An example of a routine eye contact hazard is getting a compound squirted into your eye. Eye contact with foreign substances is always bad, and this accounts for our basic rule: you must wear safety goggles at all times. However, because eye contact is a routine and universal hazard, you only need to list eye contact hazards in your notebook for compounds that are unusually reactive towards eye tissue. All compounds that are labeled as lachrymators belong in this “must list” category. Lachrymators irritate eye tissue to an extreme degree and mere vapors of a lachrymator can initiate eye irritation and damage. Notice that goggles, our routine method for preventing eye contact with foreign substances, do not control vapors well. The inadequacy of goggles in dealing with lachrymators is a perfect indication that lachrymators need to be listed as special hazards in your lab notebook.
Similar reasoning applies to inhalation hazards. Our routine assumption is that breathing large amounts of any organic vapor is bad for you (even if the vapors were not intrinsically harmful, they could reduce the amount of oxygen entering your lungs). To prevent this, we require you to perform all experiments in a fume hood.
Does this mean you can skip listing “inhalation hazards” in your notebook? Not necessarily. Notice that “perform all experiments in a fume hood” does not eliminate the possibility of taking a compound outside the hood to weigh it, dispose of it, or store it. A compound that produces toxic (or odorous or explosive) vapors should never be taken outside the fume hood. Moreover, every person who enters the lab needs to be informed that you are working with a compound that produces dangerous vapors. Compounds that produce vapors of these sorts (toxic, odorous, explosive) are not adequately managed by our basic safety precautions and must be treated as unusually hazardous, i.e., you must list the appropriate hazard information and handling instructions in your lab notebook (this may include special procedures for measurement, storage, and disposal of the compound).
Skin exposure poses a different kind of problem. First, skin may tolerate more chemical exposure than eyes and lungs. Second, different kinds of gloves provide different levels of protection, and this protection diminishes over time. This explains why we don’t have a basic safety rule regarding the wearing of gloves: gloves may not protect you. That said, if our basic safety rule (gloves not required) appears to be inadequate for a given compound, you must treat the compound as hazardous and list the appropriate information in your notebook. Because different kinds of gloves have different properties, it is your responsibility to decide when gloves are appropriate and what kind of gloves are appropriate (EHS and the Stockroom can provide you with information about the chemical properties of different types of gloves). A good starting point is to identify any compound that is described as corrosive, or reactive (e.g., aqueous base), or strongly penetrating (e.g., DMSO), or as posing a health concern (e.g., allergens, carcinogens, teratogens, toxics, and so on).
This discussion hardly exhausts the list of possible lab hazards. Here are some others that you may not have thought about that should also be listed in your notebook:
- objects that are extremely hot or cold (contact with these can damage your skin; hot objects can also initiate a chemical reaction, fire, etc.);
- any part of an experimental procedure that is described as “exothermic” or that involves a vigorous chemical reaction;
- any procedure that produces a gaseous product (gas confinement builds up pressure inside an apparatus, and creates a risk of explosive release, or perhaps even a chemical explosion in the case of reactive gases like hydrogen);
- any compound that has the potential to produce an exothermic, vigorous, or explosive reaction when it comes into contact with other substances (pay special attention to water-sensitive and air- or oxygen-sensitive compounds).