How is a pesticide’s toxicity classified?

A pesticide's toxicity is classified primarily by its LD50 value, which stands for "lethal dose for 50% of the population." The LD50 measurement is a standard way to assess the acute toxicity of a substance, indicating how much of the pesticide must be ingested, inhaled, or absorbed to cause death in half of a test population, usually laboratory animals. This quantitative value allows for comparisons between different pesticides and gives insights into their potential risks to humans, wildlife, and the environment.

The use of LD50 is crucial because it provides a scientific basis for understanding the toxicity levels and helps in categorizing pesticides according to their hazardous nature. Pesticides with lower LD50 values are considered more toxic, while those with higher values are less toxic. This classification can inform safe handling practices, application rates, and regulatory requirements.

In contrast, the other options do not serve as standardized or universally accepted methods for classifying toxicity. Chemical composition may influence toxicity but does not provide a clear metric for comparison. The method of application affects exposure risk but does not classify inherent toxicity. Lastly, the cost of a product bears no relation to its toxicological properties.