Why do scientists wear lab coats? In every stereotypical scene of a laboratory, you see scientists shaking flasks or micropipetting in lab coats. What function do lab coats serve other than a sort of seal of pure epistemological approval? Is it just to make them look more official?
When I was in chemistry lab in school or working in my current lab, I never understood the protective properties of lab coats. I've heard explanations that range from protection of the scientists to protection of the science itself. Scientists work with all sorts of dangerous and strong acids, but how does a heavy cotton bathrobe protect against concentrated hydrochloric, nitric, or hydrofluoric acids? As for the samples, I've heard that the dust on my clothing will contaminate them. While this is true for U-Pb dating, how does a lab coat stop the dust from billowing outward?
Sir or madam, your question makes Science think back to the times when wearing a lab coat saved him from misery, pain, or embarrassment. Like the time he was injecting mice with a gene-therapy virus in a two-person hood, and his partner missed the sharps container between them, dropping the mouse and virus-infested needle onto Science's lab-coat-covered leg instead. Science got nary a scratch on the skin from that one. Or the time a student helper grabbed a just-boiled beaker of water—remember, kids, hot glass looks like cold glass—and dropped it and the scalding water onto Science's lab coat. Or the time he was wearing a bleach-stained shirt with a mushroom cloud on it when television cameras were rolled into the lab. All led to Science's grand unified theory of wearing a lab coat. One should wear a lab coat when:
1. Working with dangerous reagents, particularly in liquid form. We'd all rather have all that thick cotton absorb the nasty stuff than our skin.
2. Working with a new or careless colleague. Students are great fun but tend to do foolish things.
3. Working with the public or the media looking for an authentic lab experience.
But, as you note, lab coats aren't all that protective or useful—despite the dangers of much of what scientists work with in a lab. Ethidium bromide, used to make DNA glow in gels, causes stomach cancer. Acrylamide, used to make protein gels, is a nasty neurotoxin. Many organic solvents, like carbon tetrachloride, pummel the liver. The lab coat itself—white, long sleeved, drooping nearly to the floor, with abundant pockets—acknowledges these risks to health and longevity taken on by scientists for the greater good. It's a symbol of our altruism.
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