Acute Exposure: An intense exposure over a relatively short period of time.
Asphyxiant : A chemical (gas or vapor) that can cause death or unconsciousness by suffocation.
Carcinogen: A substance or physical agent that may cause cancer in humans or animals.
Chronic Exposure: A prolonged exposure occurring over days, weeks or years.
Combustible Liquid: Liquids having a flash point at or above 100 degrees. Not as ignitable as Flammables.
Corrosive: A substance that causes visible destruction or permanent changes in human skin tissue at the site of contact, e.g. acids and bases.
Flammable Liquid: A liquid having a flash point below 100 degrees; more ignitable than combustible liquids.
Flash Point: The lowest temperature at which a liquid gives off enough vapor to form an ignitable mixture and will burn when a source of ignition is present.
Hepatotoxic, Nephrotoxic, Neurotoxic: Substances which are toxic to the liver, kidneys and nervous system, respectively.
Incompatible: The term applied to two substances to indicate that one material cannot be mixed with the other without the possibility of a dangerous such as fire, explosion or release of toxic vapors.
Irritant: A substance that produces irritating effect when it contacts skin, eyes, nose, or respiratory system.
Lethal Concentration (LC50): The concentration of air contaminant that will kill 50% of the test animals in a group during a single exposure (inhalation exposure). Generally expressed in units of parts per million or mg of contaminant m3 of air.
Lethal Dose (LD50): The dose of a substance that will kill 50% of the test animals in a group over a specified period of time following exposure. Generally in units of mg of material per kg of subject body weight.
Mutagen: Anything which can cause a mutation in genetic material of a living cell. All mutagens are not carcinogens.
Oxidizer: A substance that readily gives up oxygen to stimulate combustion of an organic material.
Permissible Exposure: A human exposure limit that is published and enforced by OSHA as a legal standard. PEL may be either time-weighted-average (TWA). Limit: Exposure limit (8 hour), a 15 minutes short term exposure limit STEL, or ceiling © limit. Expressed in ppm or mg/m3.
Sensitizer: A substance which may cause no reaction in a person during initial exposures, but upon a later exposure will cause an allergic response to the substance.
Teratogen: A substance that may cause physical defects in the developing embryo or fetus when a pregnant female is exposed to that substance.
Threshold Limit Value: Similar to PEL above but are not legal standards for human exposure. Determined and published by the American Conference of Government Industrial Hygienists (ACGIH).