Environmental Health and Safety

MSDS Glossary

L
Liter is a metric unit of capacity. A U.S. quart is about 9/10 of a liter.
Lacrimation
Secretion and discharge of tears.
Label
Notice attached to a container, bearing information concerning its contents.
LC
Lethal concentration is the concentration of a substance being tested that will kill.
LCL
Lethal concentration, low, lowest concentration of a gas or vapor capable of killing a specified species over a specified time.
LC50
The concentration of a material in air that will kill 50 percent of a group of test animals with a single exposure (usually 1 to 4 hours). The LC50 is expressed as parts of material per million parts of air, by volume (ppm) for gases and vapors, or as micrograms of material per liter of air (μg/l) or milligrams of material per cubic meter of air (mg/m3) for dusts and mists, as well as for gases and vapors. See also Highly Toxic and Toxic.
LD
Lethal dose is the quantity of a substance being tested that will kill.
LDL
Lethal dose low, lowest administered dose of a material capable of killing a specified test species.
LD50
A single dose of a material expected to kill 50 percent of a group of test animals. The LD50 dose is usually expressed as milligrams or grams of material per kilogram of animal body weight (mg/kg or g/kg). The material may be administered by mouth or applied to the skin. See also Highly Toxic and Toxic.
LEL, or LFL
Lower explosive limit, or lower flammable limit, of a vapor or gas; the lowest concentration (lowest percentage of the substance in air) that will produce a flash of fire when an ignition source is present. At concentrations lower than the LEL, the mixture is too "lean" to burn. Also see UEL and Flammability Range.
Lethal Concentration
See LC50.
Lethal Dose
See LD50.
Local Exhaust
A system for capturing and exhausting contaminants from the air at the point where the contaminants are produced (welding, grinding, sanding, or other processes or operations). Also see General Exhaust.

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