Safety with Common Chemicals in the EM Lab

Sodium Cacodylate: contains arsenic (As) and can be absorbed through the skin. NOTE: Some buffers (e.g. cacodylate and veronal acetate) contain toxic components, and must be handled with caution. Use gloves at all times and dispose of in an appropriate manner.

Aldehydes: mucus membrane irritant and fixative, shown to cause cancer in the nasal cavity and skin.

Osmium Tetroxide: vapors and liquids are toxic, irritate, and fix mucus membranes.

• Handle in a well-ventilated room and open only in a fume hood.
• Handle ampoules with disposable gloves. Use double bottles and seal with parafilm.
• DO NOT hold your breath when using OsO₄. Your nose is a very sensitive detector of dangerous fumes, and you may be able to detect potential problems, such as fume hood malfunctions, if you breathe normally.

Propylene Oxide: Carcinogen similar to aldehydes.

• A very volatile solution. Must be opened and used at room temperature. NEVER HEAT.
• Store in a cool place.

Embedment Resins: Irritants and possible carcinogens. Most embedding resins may cause dermatitis

• When preparing the mixtures and during embedding procedures, ALWAYS use disposable gloves. Cover working areas with paper towel or diapers and wipe spills immediately with alcohol.
• DO NOT use alcohol to remove resins from your skin, it increases penetration. Use soap and water to remove resins.
• Get medical attention for any suspicious skin rash.
• Harden/polymerize all waste resin before disposal.
• For disposing, follow all local/regional requirements and wrap discarded containers, beakers, vials, pipettes, etc., carefully.
• Never pour any plastic containing solutions (e.g. propylene oxide-epon mixture) down the drain. They will harden.

Lead and Uranyl Acetate: Heavy metal poisoning.

DMSO: Facilitates absorption through the skin of any material contained in it.

Cryogenics: Liquid nitrogen and helium are the most common EM lab cryogens and pose several hazards.

1. Never use cryogens in an enclosed space. Cryogens displace oxygen from the room, causing asphyxiation.
2. Sealed containers can build up pressure resulting in explosions. Always check that the pressure relief valve is not frozen shut.
3. Direct contact with liquid or equipment exposed to cryogen can cause frostbite and burns.

Compressed Gas Cylinders: ALWAYS secure all cylinders to wall or stable unit using straps or chains. NEVER move a cylinder without first securing the cap over the valve.