Danger in Familiarity

As a chemist, I use hazardous materials every day and that is OK because I know they are dangerous so I treat them with the proper handling and respect they deserve. But are we underestimating the danger of some things we use regularly? Possibly a case of familiarity breeds contempt leads to trouble?

The first time you use a chemical, especially one you are aware is dangerous, you take special care. But it is often the case that a successful reaction will be revisited several times, by which time the chemical that you handled so carefully upon that first meeting is an old friend that never did you any harm before.

Clearly there are exceptions to this – I still feel a little nervous whenever I have used sodium cyanide or osmium tetroxide – and I am not suggesting anyone is neglecting their personal protection, just that you might not be treating it with quite the respect it perhaps deserves.

My classic example for this: concentrated acids. They are ubiquitous in laboratories everywhere. Everyone uses them, a standard chemical – and yet I bet a significant number of working chemists own clothing that has an acid spot or two on it somewhere, which is not exactly an indication of all due care being taken. I recall an undergraduate laboratory I did, where I noted to one of the professors that the chemicals we were using we all pretty dangerous. I don’t recall which ones, but I think sodium azide was in there. The professor regarded me with fond concern for my welfare and commented that he felt that the concentrated acids were the most dangerous things in the laboratory.

Another candidate for underappreciated dangers would be that entire cabinet of flammable solvents. We see that fiery symbol on it every day and it has been more years than I care to mention since I saw a bunsen burner in an organic lab, so those should be pretty safe, right? Even disregarding the additional dangers presented by ethers (peroxide formation) and possible carcinogens nestled in with the flammables (I’m looking at you, dichloromethane), the simple danger of fire in an organic lab cannot be overstated. I recall a story (which my Google skils were not able to pull up) where a faulty shelf in a flammable cabinet collapsed, causing a huge fire and destroying the lab. [UPDATE: a colleague knew the answer - it was at Ohio State University - C&E News story here] Less drastic war stories are not uncommon.

What other chemicals do you think are thought too familiar to be dangerous?

Learning from UCLA

This week’s Chemical & Engineering News has an amazing article on the recent tragic death of Sheharbano (Sheri) Sangji, a research assistant in the lab of Professor Patrick Harran at UCLA. If you have not read it, I highly recommend that you do.

This incident in particular has brought academic labs under the spotlight with regard to their attitude to safe practices in the lab. Many of my colleagues have war stories from their times in academia, talking about procedures that would not be tolerated in an industrial setting. Occasionally people talk about how it was because we were young and inexperienced and sometimes it is about how much money that there is to spend on safety, but generally I think most feel it is about getting results from their graduate students in a short time frame. It is in the interest of both student and professor that the work being done produces papers. The result: long hours and lax safety practices.

In some ways, though, it is a surprise that Sheri’s accident involved t-butyl lithium (tBuLi), which is a highly pyrophoric material (meaning it spontaneously catches fire in the air). When handling such a known danger as this, most people would take extra precaution, treating it with the proverbial kid gloves. This was (as far as we can tell from the investigation done by C&E News) only the second time she had used this material – certainly not a case of overly familiarity.

My personal theory is that Sheri treated the larger scale reaction as she had her previous experiment. She figured that she could just use a syringe to deliver the t-BuLi to the reaction, as she had done before. OK, it would take several aliquots, but that would not be a problem. It would save her having to use a cannula and pressure to push the reagent into another flask. I expect the first aliquot went relatively smoothly, but when she went to do that again, the syringe plunger became more difficult to pull out, then it gave suddenly and pulled all the way out.

This is often an issue when scaling up a reaction. What works on with only a small amount suddenly does not work with a much larger amount. The slightly warm reaction on 10 mL scale becomes a spontaneous reflux on 100 mL scale. The reaction suddenly doesn’t stir so well. Or, as in this case, the volume of reagents overwhelms the way that you have to deliver it.

I think I am personally so interested in this story because it is, to coin a phrase, happening where I live, that is in the laboratory, doing reactions and using potentially dangerous reagents. I can almost imagine the thought processes of the young chemist, as she tries to deal with the unfolding situation. You do not make good decisions when you are trying to improvize, you jury-rig and make do. Only by looking at the procedure before entering the lab and thinking “what is the best way to do this?” and “what can go wrong?” and “what will I do if it does?” can chemistry be safely be done, without needless loss of young lives.