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More Bad Laboratory Chemicals, and What They Do to You

More Bad Laboratory Chemicals, and What They Do to You

It’s all too easy to forget how many common lab chemicals are dangerous.   To remind you, I pulled together a list (and a few cautionary tales) of hazardous yet ubiquitous chemicals a few weeks back). It proved popular, so I’ve furthered my efforts to bring you even more chemicals that you should not be messing with the lab. Enjoy, and be safe out there!

Benzene.  This flammable, lipophilic solvent irritates the skin, lungs, and eyes.  Even worse, benzene easily crosses skin and enters the bloodstream.  The body then converts it to toxic metabolites which can damage the brain and heart, suppress the immune system, and even cause leukemia!

Ethanol.  This ubiquitous solvent and disinfectant is readily absorbed through the lungs and gastrointestinal tract (as many of us already know!).  In addition to depressing the central nervous system, ethanol poses a risk because it is so flammable, as one researcher carelessly sterilizing equipment with ethanol and a flame discovered.


Imidazole.  While protein biochemists are likely familiar with imidazole’s use in protein purification, they may not know that imidazole is very corrosive.  It can severely burn the skin and eyes, and harm mucous membranes if inhaled!

Liquid Nitrogen.  As a cryogenic liquid, liquid nitrogen can cause terrible freezer burns and tissue damage.  Furthermore, it poses a suffocation risk when the liquid warms enough to become a gas: the gas expands rapidly, displacing oxygen from the air and potentially leading to suffocation in unventilated quarters.  This rapid gaseous expansion can also cause explosions in improperly-sealed dewars, as a lab in Texas A&M University discovered.

Osmium Tetroxide.  This tissue fixative also acts as an oxidizer with toxic vapors which are especially damaging to the lungs and eyes.  Even at low concentrations, its vapors cause tearing, a gritty sensation, and the disturbing (but psychedelic) effect of perceiving rings around bright lights.

Phenol.  This flammable disinfectant should definitely be used in the fume hood (and not just because it has a sickly-sweet smell!).  Phenol can corrode the skin and also damage the lungs when inhaled.   A high concentration of it can even cause cardiac arrhythmia by blocking cardiac sodium channels.

Picric Acid.  Commonly used in tissue fixatives, picric acid can stain hair yellow and irritate the eyes and skin.  Repeated exposure causes progressively worse dermatitis.  Even worse, it damages the liver and kidneys. As if its toxicity wasn’t enough, picric acid corrodes metals and, improperly stored, can crystallize out of solution – leading to an explosion risk!

Sodium Dodecyl (Lauryl) Sulfate.  As an anionic surfactant, SDS is used at low concentrations in cosmetics and toothpastes.  Scientists will likely be familiar with SDS as one of the components in protein gels.  Although SDS has very low toxicity, it can be corrosive and damaging to skin, especially at concentrations greater than 10%.

Sulfuric Acid.  This hygroscopic acid corrodes the skin and eyes via coagulating necrosis.  To make matters worse, it releases heat when mixed with alcohol or water – meaning that people splashed with sulfuric acid may also suffer from thermal as well as acid burns.  Unlike alkaline burns, sulfuric acid effectively forms a scab of coagulum, which restricts further penetration into the exposed tissue.  Wear your butyl rubber gloves when working with concentrated sulfuric acid! Latex will not protect you, as one unfortunate researcher discovered.

Xylene.  Unlike other organic solvents, xylene doesn’t easily cross the skin.  However, it can dry and irritate the eyes, mucous membranes, and skin.  Xylene does readily enter the body when inhaled: once inside, it intercalates into neuronal cell membranes and changes nerve impulse transmission.  This anesthetic effect especially perturbs the cerebellum and motor coordination.

I hope this list has refreshed you on lab chemical hazards – as well as why you should work in the fume hood!


Ashbrook PC, Houts TA.  Picric acid.  Chem Health Safety.  2003;10(2):27.

Final report on the safety assessment of sodium lauryl sulfate and ammonium lauryl sulfate.  Int J Toxicol.  1983;2(7):127-181.

Luttrell WE and Conley NL.  Toxic tips: benzene.  Chem Health Safety.  2011;18(4):32-33.

Luttrell WE.  Toxic tips: sulfuric acid.  Chem Health Safety.  2003;10(1):40-41.

Luttrell WE.  Toxic tips: Xylene.  Chem Health Safety.  2012;19(2):34-35.  34-35.

National Institute for Occupational Safety and Health.  Osmium tetroxide.  NIOSH Pocket Guide to Chemical Hazards.  2011. 

National Institute for Occupational Safety and Health. Picric acid.  NIOSH Pocket Guide to Chemical Hazards.  2011. 

PubChem.  Benzene – Compound Summary.  

PubChem.  Ethanol – Compound Summary

PubChem.  Osmium Tetroxide – Compound Summary. 

Sigma-Aldrich.  Material Safety Data Sheet: Imidazole.  2012. 

University of California – Santa Barbara Environmental Health and Safety.  Laboratory Safety Fact Sheet #13 Cryogens. 

Walters D.  Lesser known hazards in histopathology laboratories.  Chem Health Safety.  2001;8(6):28.



  1. Nick Oswald on June 14, 2013 at 11:18 am

    @NSM – I’ve fixed the link … thanks for the headsup.

    @MichealA – Good call about SDS. It is nasty stuff.

  2. MichaelA on June 11, 2013 at 9:55 am

    One more thing to add about SDS: Its a highly potent allergen. So always wear an appropriate dusk mask when you handle the substance when making buffers. When its dissolved, its less of a problem.

  3. NSM on June 10, 2013 at 3:24 pm

    Very nice post, thank you!
    Could you please fix the link you have included in the end of your explanation about sulfuric acid?

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