Legal Standard
40 CFR § 156.62
LC50 (Median Lethal Concentration)
Statutory Definition:
The concentration of a chemical in air (inhalation exposure, mg/L or ppm) or water (aquatic toxicity, mg/L) that kills 50% of the test organism population during a specified exposure period.
Practical Exam Application:
Essential for determining respiratory protection requirements for fumigants and assessing environmental toxicity to gamefish and aquatic invertebrates.