Lab Safety Myths

Many lab safety mistakes don’t come from carelessness but from beliefs that sound sensible and are wrong. “Gloves protect my hands.” “It’s only dilute.” “I’ll neutralise the acid on my skin.” Each of these can lead to real harm. Here are thirteen common myths, with the facts and the chemistry that explains them.

Myth 1: “Gloves protect against everything.”

Reality: Gloves are chemical-specific. Each glove material (nitrile, latex, neoprene, butyl rubber, laminate) resists some chemicals and lets others through, sometimes within seconds. Many organic solvents pass through thin disposable gloves quickly, and a chemical trapped inside a glove against your skin can be worse than no glove at all.

What to do: Check the safety data sheet (section 8) or the glove manufacturer’s chart. Remove and replace a glove as soon as it’s contaminated. The tragic case of a chemist exposed to dimethylmercury through latex gloves is told in famous lab accidents.

Myth 2: “If it’s dilute, it’s safe.”

Reality: Dilute solutions are less hazardous, not harmless. Dilute sodium hydroxide can still cause serious eye damage; alkalis are particularly dangerous to eyes because they break down tissue and keep penetrating. Some substances, such as mercury compounds or dilute hydrofluoric acid, are hazardous even at low concentrations. See hydrofluoric acid: weak but dangerous.

What to do: Treat every chemical according to its actual hazard at the concentration used. Wear eye protection for dilute solutions too.

Myth 3: “Neutralise an acid splash on skin with a base.”

Reality: Neutralisation is exothermic, so it adds a thermal burn to the chemical one. You’re also unlikely to add exactly the right amount, so you may swap an acid burn for an alkali burn.

What to do: Rinse with plenty of running water for at least 10–15 minutes. Water dilutes, removes and cools. See enthalpy of neutralisation for how much heat neutralisation releases, and acid safety.

Myth 4: “Water puts out every fire.”

Reality: Water can make some fires much worse:

• Burning solvents and oils that float on water are spread by it.
• Reactive metals such as sodium and potassium react with water to release hydrogen, which burns.
• Electrical fires plus water risk electric shock.

What to do: Smother small fires (heat-resistant mat, fire blanket), and use the correct extinguisher type. Always alert the teacher first. See most reactive metal.

Myth 5: “Smelling a chemical is a good way to identify it.”

Reality: Some toxic gases have no smell at all (carbon monoxide). Others, like hydrogen sulfide, deaden your sense of smell at high concentrations, so you stop noticing just as they become most dangerous. Many vapours irritate or damage the airways.

What to do: Only waft a small amount towards you when a method specifically tells you to. Identify substances with proper tests. See identifying ions.

Myth 6: “Small quantities can’t hurt you.”

Reality: Toxicity depends on the substance as well as the amount. Some compounds are harmful in milligram quantities or can be absorbed through skin. Small quantities also add up if you’re exposed repeatedly.

What to do: Scale down where possible (it genuinely reduces risk; see microscale chemistry), but still follow every precaution for the substance.

Myth 7: “Safety glasses aren’t needed if I’m only watching.”

Reality: Splashes and flying glass don’t care whose experiment they come from. A beaker that cracks on a hotplate or a test tube that spits while heating can reach people metres away.

What to do: Eye protection stays on whenever anyone in the lab is working with chemicals, heat or glassware under stress.

Myth 8: “Contact lenses are fine under safety glasses.”

Reality: Guidance on this has changed over time and varies between institutions. Contact lenses don’t protect the eye, and if a chemical gets into the eye, it can be harder to rinse fully with a lens in place. Many labs now permit lenses with appropriate eye protection, while some still restrict them.

What to do: Follow your lab’s policy, always wear proper eye protection, and tell the teacher or first aider if you wear lenses and have an eye splash, so they can be removed during rinsing.

Myth 9: “The fume cupboard makes anything safe.”

Reality: A fume cupboard only protects you if it’s working, the sash is at the right height, you’re working well inside it, and it isn’t cluttered. It doesn’t protect your hands and eyes from splashes, and it won’t contain a large explosion.

What to do: Check the airflow indicator, keep the sash low and still wear full PPE.

Myth 10: “Bench-top labels don’t matter for my own solutions.”

Reality: An unlabelled beaker of colourless liquid could be water, dilute acid or a solvent. Someone else, or you in an hour, might mistake it. Unknown chemicals are also difficult and expensive to dispose of safely.

What to do: Label every container with the name, concentration and your name, the moment you fill it. See chemical storage.

Myth 11: “Natural or ‘green’ chemicals are always safe.”

Reality: Many naturally occurring substances are hazardous: essential oils can be skin sensitisers, citric acid irritates eyes, and some plant extracts are toxic. Whether a substance comes from a plant or a factory tells you nothing about its hazards; its chemical properties do.

What to do: Check the hazards of every substance, including household and “natural” products.

Myth 12: “Accidents only happen to careless people.”

Reality: Serious accidents have happened to highly skilled, experienced chemists, often during routine work or when a small change (a larger scale, a different reagent, working alone) wasn’t assessed. Confidence can lead to shortcuts.

What to do: Follow procedures every time, carry out a risk assessment whenever something changes, and report near-misses.

Myth 13: “If I can’t see a reaction happening, nothing dangerous is going on.”

Reality: Many hazards are invisible. Colourless gases such as carbon monoxide or hydrogen chloride can form without any visible sign, a hotplate can be dangerously hot without glowing, and some reactions have an induction period before they suddenly speed up.

What to do: Follow the method’s timings, use a fume cupboard where required, and treat equipment as hot until you’ve checked.

Quick check: fact or myth?

1. “I should rinse an eye splash with water for at least 10 minutes.” → Fact.
2. “Nitrile gloves protect against all solvents.” → Myth.
3. “I can pour a small amount of solvent on a fire to see how it burns.” → Myth, and very dangerous.
4. “I should report a near-miss even if nobody was hurt.” → Fact.

Key takeaways

• Protective equipment is hazard-specific; gloves in particular must match the chemical.
• Dilute, small or natural doesn’t mean harmless.
• Rinse chemical splashes with water; never try to neutralise them on skin.
• Water spreads some fires; smother small fires and alert the teacher.
• Labels, working fume cupboards and procedures protect everyone, including experienced chemists. See lab safety rules.