Technical Specifications & Units
- Standard Unit: Expressed in milligrams of substance per kilogram of body weight (mg/kg).
- Variable Factors: Every LD50 value must specify the species (e.g., rat, mouse), the route of administration (oral, dermal, intravenous), and often the timeframe of observation (e.g., 24 hours or 14 days).
- Inverse Relationship: A lower LD50 value indicates higher toxicity, as a smaller amount is required to be lethal.
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Toxicity Classification Scales
Regulatory bodies use LD50 to categorize chemicals into hazard classes. For example, under the GHS (Globally Harmonized System) for acute oral toxicity:
- Category 1 (Extremely Toxic): LD50
5 mg/kg
50 mg/kg
300 mg/kg
2000 mg/kg
- Category 5 (Relatively Safe): LD50 > 2000 mg/kg