What substance is considered to be the most toxic?
This is a very difficult, if not impossible, question to answer. Several factors need to be considered when discussing toxicity. These include the route of exposure, i.e., skin, inhalation, ingestion, etc., the duration of exposure, how much of the substance you were exposed to, and a number of other factors. ATSDR can provide you with a list of chemicals most frequently found at Superfund sites as well as documents explaining how the ranking is determined.
