Acute toxicity describes the adverse effects of a substance which result either from a single exposure or from multiple exposures in a short space of time (usually less than 24 hours)

OSHA defines a chemical as being highly toxic if it falls within any of the following categories:

(a) A chemical that has a median lethal dose (LD50) of 50 milligrams or less per kilogram of body weight when administered orally to albino rats weighing between 200 and 300 grams each.

(b) A chemical that has a median lethal dose (LD50) of 200 milligrams or less per kilogram of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between two and three kilograms each.

(c) A chemical that has a median lethal concentration (LC50) in air of 200 parts per million by volume or less of gas or vapor, or 2 milligrams per liter or less of mist, fume, or dust, when administered by continuous inhalation for one hour (or less if death occurs within one hour) to albino rats weighing between 200 and 300 grams each.

A list of some examples of acute toxins can be found here.

When working with chemicals with high acute toxicity minimize exposure to these substances by:

• Working in areas labeled with warning signs and restricted access
• Always use a fume hood or other containment devices for procedures with the potential to release vapors or fumes
• Avoid skin contact by wearing proper PPE such as, gloves, goggles, lab coat with long sleeves and closed toe shoes
• Wash arms and hands after working with these materials
• Maintain records of the amount of the toxin used
• Assure that at least two people are present at times of use
• Be aware of any antidotes incase of accidental exposure