Ethidium bromide is suspected to be highly toxic as a mutagen because of its ability to bind with and alter the structure of DNA. It also has the potential to be carcinogenic and teratogenic. However, no studies have been able to prove this conclusively. 

Acute exposure can occur through inhalation, ingestion or direct contact to the skin. Once exposed to ethidium bromide, it can cause irritation of the upper respiratory tract, skin, mouth, and eyes.