Ethidium bromide

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Ethidium Bromide, often abbreviated EtBr

  • Intercalating agent that inserts itself between DNA base pairs
  • Fluorescent under UV light

Caution: Carcinogen/Mutagen

Handle with Nitrile gloves

Hazards and Precautions

Ethidium Bromide (EB) is commonly used as a non-radioactive marker for identifying and visualizing nucleic acid bands in electrophoresis and in other methods of gel-based nucleic acid separation. EB is a dark red, crystalline, non-volatile solid, moderately soluble in water, which fluoresces readily with a reddish-brown color when exposed to ultraviolet light (UV). Its formula is 2,7,-Diamino-10-ethyl-9-phenyl-phenanthridium bromide, CAS# 1239-45-8. Although it is an effective tool, its hazardous properties require special safe handling and disposal procedures.


EB is a potent mutagen and moderately toxic after an acute exposure. EB can be absorbed through skin, so it is important to avoid any direct contact with the chemical. EB is also an irritant to the skin, eyes, mouth, and upper respiratory tract. It should be stored away from strong oxidizing agents in a cool, dry place, and the container must be kept undamaged and tightly closed.

Safety Precautions

People using EB should follow several safety procedures. The laboratory's Chemical Hygiene Plan should reference this Fact Sheet, which outlines safe handling of EB and proper cleanup procedures. EB users should receive documented safety training on its hazards. EB must appear on the laboratory's chemical inventory, with accurate estimates of on-hand and yearly use quantities. Pure EB should only be handled in a fume hood, with the user wearing protective equipment that includes a lab coat, closed-toe shoes, chemically resistant gloves, and chemical safety goggles (not just safety glasses).

Nitrile is an effective barrier to short-term exposure to EB. Gloves, such as Best Manufacturing's N-DEX® or others made of 100% nitrile, are available from most laboratory supply distributors. EB users should wash their hands after removing their gloves, even if they are certain the gloves weren't punctured.

An emergency eyewash and shower should be accessible nearby. Like all other toxics, EB should be used in a specially designated area where no eating or drinking is allowed. When using ultraviolet light to visualize EB, the user must wear UV-blocking eyewear or work in a UV cabinet with shielding glass in place.