A Chemistry Fairy Tale
Once upon a time a chemist needed to transfer a small amount of a nasty chemical from one container to another. This chemist always used good laboratory practices and followed all the laboratory safety rules and regulations. Before she began to work with this chemical she donned her protective lab coat, goggles, and disposable latex gloves. Because the chemical she would be transferring was a highly toxic and volatile liquid compound, the transfer would be done in a chemical fume hood which would place a glass barrier between her and the nasty chemical and draw vapors away from the air she would breathe.
The chemist drew a small amount of the magical nasty chemical out of the vial, deposited it into a pencil-thin glass sample tube, and then pipetted the rest into a small screw-top storage vial. In the process, a drop or two of the magical liquid dripped from the pipette onto her left glove. She sealed and labeled the sample tube and storage vial, peeled off her gloves, left them in the fume hood, and then thoroughly washed her hands as she always did. Little did the chemist know that the magical liquid that had landed on her glove had rapidly penetrated her glove and then her skin and was already beginning a slow, unseen journey into her blood and into her brain.
But how could she have known this? There were no visible holes in her glove. The magical chemical hadn't burned or otherwise announced itself as it seeped into her skin. Even the wetness of the drop or two would have been indistinguishable from the clamminess that builds up inside rubber gloves.
Five months later the deliberate, focused, and precise scientist found herself stumbling into walls and slurring her speech. The chemist who was never sick suddenly was asking her husband to pick her up from work because she didn't feel well enough to drive home. She finally saw a doctor and was admitted to the hospital. Samples of the chemist's blood and urine were rushed to a lab for testing.
The lab results confirmed the evil chemical had entered her body and was residing in her brain where it was attacking her nervous system at an alarming rate. Her field of vision kept shrinking, her hearing was shutting down and she was struggling to speak. The doctors at the hospital treated her with chelation therapy which would act like a magnet, attracting the chemical and binding it into a substance her body could excrete.
Then, barely three weeks from the moment she noticed anything was wrong, the chemist slipped into a coma and died. –The end.
Unfortunately, this fairy tale is true. The chemist was Dr. Karen Wetterhahn, the gloves she was wearing were latex and the magical chemical was dimethylmercury. The disposable latex gloves gave Wetterhahn needed dexterity and no one knew at the time that dimethylmercury soaks through them at an alarmingly rapid rate.
Seven types of disposable gloves found in Wetterhahn's lab were sent to Intertek Testing Services for analysis. The results were shocking. Dimethylmercury penetrated the latex gloves in 15 seconds or less, possibly even instantaneously. The other types of disposable gloves from the lab failed as quickly.
After the investigations the recommendations for protection when handling dimethylmercury were as follows: "a highly resistant laminate glove (SilverShield or 4H) should be worn under a pair of long-cuffed, unsupported neoprene, nitrile, or similar heavy-duty gloves."
Until the accident, no one realized the extreme toxicity of dimethylmercury. Unfortunately Dr. Wetterhahn's accident showed that dimethylmercury was far more toxic than anyone thought. Merely absorbing a drop or two placed her in the lethal range.
No single glove material is resistant to penetration by all chemicals. The following are two excellent resources for glove selection:
- http://www.bestglove.com/site/chemrest/default.aspx This link will take you to a free interactive web-based tool by Best Gloves.
- http://www.ansellpro.com/download/Ansell_8thEditionChemicalResistanceGuide.pdf This link will take you to Ansell Gloves' 8th edition of its Chemical Resistance Guide.
Please make sure the gloves you are wearing are resistant to the chemicals you will be working with before you begin your work, practice safe science, always wear all appropriate personal protective equipment and use good laboratory practices.