Final answer:
LD50 refers to the dose that kills 50% of a test population and is a critical index of a chemical's acute toxicity. LDlo is the lowest observed lethal dose, and LC50 indicates the concentration in air or water that is lethal to 50% of a population. These are standard measures used to compare toxicity levels of different substances.
Step-by-step explanation:
The LD50 is a toxicological measurement that stands for lethal dose, 50%. It is the estimated amount of a substance expected to kill 50% of a test population, usually animals like rats or mice, under controlled conditions. The LD50 value is important in the assessment of a substance's acute toxicity and is typically expressed in milligrams of the substance per kilogram of body weight of the test animal (mg/kg).
LDlo stands for "lethal dose low" and refers to the lowest dose that has been observed to cause death in a population of test animals. Whereas LC50 stands for "lethal concentration 50%" and represents the concentration of a substance in air or water that kills half of the test animals' population in a specified period.
These measures are critical when evaluating the potential hazards of chemicals, both for environmental and human health. It's important to note that LD50 and LC50 values may vary significantly between species, and thus, they only provide a general approximation when assessing risk to humans.