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In toxicology, the median lethal dose, LD 50 (abbreviation for "lethal dose, 50%"), LC 50 (lethal concentration, 50%) or LCt 50 is a toxic unit that measures the lethal dose of a given substance. [1] The value of LD 50 for a substance is the dose required to kill half the members of a tested population after a specified test duration.
In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation.Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilogram of subject body weight) at which a given percentage of subjects will die.
It is calculated using the LD50 or LC50. [1] The Occupational Safety and Health Administration (OSHA) regulation (1910.134(b)) defines the term as "an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual's ability to escape from a dangerous atmosphere."
Many gases have toxic properties, which are often assessed using the LC 50 (median lethal concentration) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious or permanent injury), and/or exposure limits (TLV, TWA/PEL, STEL, or REL) determined by the ACGIH professional association.
The system is based on LD50 determination in rats, thus an oral solid agent with an LD50 at 5 mg or less/kg bodyweight is Class Ia, at 5–50 mg/kg is Class Ib, LD50 at 50–2000 mg/kg is Class II, and at LD50 at the concentration more than 2000 mg/kg is classified as Class III. Values may differ for liquid oral agents and dermal agents. [1]
"Lead is a known neurotoxin, and cadmium has been shown to cause harmful effects to bones and kidneys," says Felicia Wu, PhD, a professor of food safety, toxicology, and risk assessment at ...
Donald Trump mocked Canadian Prime Minister Justin Trudeau after his top minister’s surprise resignation following a clash on how to handle the president-elect’s looming tariffs.
In toxicology, the median toxic dose (TD 50) of a drug or toxin is the dose at which toxicity occurs in 50% of cases. [1]: 73 The type of toxicity should be specified for this value to have meaning for practical purposes.