What is the primary limitation of using PECQs in assessments?

The primary limitation of using PECQs lies in their potential failure to fully account for the complex interactions and bioaccumulation of substances within ecosystems. PECQs are designed to provide a simple quotient that compares environmental concentrations of a substance against benchmarks for toxicity. However, ecosystems are inherently complex, and the behavior of pollutants can vary significantly due to various environmental factors.

In real-world situations, the interactions among different chemical substances, as well as their combined effects on organisms, can lead to outcomes that are not accurately predicted by PECQs. Additionally, bioaccumulation—not just the concentration of a single substance—plays a crucial role in determining the true risk of toxicity to organisms at higher trophic levels. Failures to incorporate these dynamics can lead to inadequately informed decisions regarding environmental protection and management measures. By highlighting this complexity, it's clear how this limitation impacts the efficacy of utilizing PECQs in environmental assessments.