Background: I recently started in a lab that regularly uses β-mercaptoethanol (βME) for protein purification. I know that the chemical is an irritant for the lungs if inhaled (mucus membranes), damaging if in contact with eyes, toxic if in contact with skin. However, I have had projects in different labs that handle this chemical differently. Some strictly only open it in the fume-hood, have designed waste in the fume-hood for any pipette tips that touch βME and always discard any protective gloves that they used while handling this chemical directly after use — so not to spread residual βME all over the lab. This also goes for any buffers that have βME in it.

In the lab that I currently work in, they open the concentrated bottle of βME in the fume hood, but they don't care too much about discarding pippete tips in designated waste nor change gloves after use (and I know that the gloves smell like βME after opening the bottle). In addition, they do not work with lammeli buffer in the fume hood (they use 4 × lammeli for SDS-PAGE). However, from the safety manual of lammeli-buffers — which also contains βME (and you can immidiately smell that) it seems to be just as hazardous as the concentrated βME.

I dont have hypochondria when it comes to lab safety, but I would like to develop a rational understanding of how dangerous this is common chemical is. In addition I belive that the fridge which we store βME in smells quite strongly of βME. Should the bottle be stored in a secondary container (plastic bag) in addition?

Question: How do people who commonly use this chemical treat it during their everyday lab routines? How hazards is it to regularly inhale trances of βME from e.g. the fridge or when people work with lammeli buffers on the lab bench? What do people think about discarding their gloves after working with it, before they start touches other lab equipment?

  • $\begingroup$ Good thinking, reasonable lab safety: People who overdo it tend to forget where the real, specific dangers are, and around them also nobody learns about them. $\endgroup$ – Karl Dec 18 '16 at 0:37

β-Mercaptoethanol is not that dangerous a chemical. Yes, you should not drink it, you shouldn’t dip your bare fingers in it, you shouldn’t inhale tons of it and you shouldn’t use it to rub yourself down. But other than that it is hardly more dangerous than most other thiols. Simple methanol is probably more toxic and is also routinely handled.

The thing about β-mercaptoethanol is that it  stinks like hell.  And it has the tendency to stick around stinking for quite some time. Like with most thio-compounds, you can smell it long before it becomes seriously dangerous; your sense of smell is a warning against being too risky. You know yourself that the gloves stink if you used the bottle, that the pipette tips stink after pipetting it and that any flasks that contained it tend to stink for quite a while afterwards.

And that is the reason why some labs rigorously segregate it from other chemicals; have dedicated wastes for pipette tips and gloves all kept under a fume it. It is all simply meant to stop the stench as early as possible, to keep it confined in a single fume hood and keep most of the lab air smelling better. The safety aspect is secondary. If you develop a routine of changing equipment every time after handling β-mercaptoethanol, you are less likely to forget to take off your glove and the lab has less smell to deal with.

Therefore, you would be doing your lab colleagues a favour by keeping the bottle confined within its own small plastic bag; but it’s only an olfactory favour, not that much a health favour.

  • $\begingroup$ to add to the answer; thiols and other sulfur compounds can be especially corrosive to metals and help them oxidize more rapidly. $\endgroup$ – A.K. Dec 17 '16 at 19:42

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