LD50
The lethal dose of a substance that causes death in 50% of test organisms, used to quantify acute oral/dermal toxicity.
Formula
LD50 (mg/kg) = lethal dose causing 50% mortality in test population
Real World
Glyphosate (Roundup), the world's most widely used herbicide, has an LD50 of around 5,600 mg/kg in rats — classifying it as practically non-toxic by acute oral exposure, though long-term and ecosystem effects remain debated.
Exam Focus
Remember: a lower LD50 means higher toxicity; always state units (mg/kg) and note that LD50 only measures acute lethality, not chronic or sub-lethal effects.
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