Chemical Contaminants and their Toxicological Effects on Aquatic Organisms and Ecosystems

Abstract

Background: The overwhelming challenge of contaminants found in water ecosystems is considered one of the major environmental issues of this century. The vast majority of this problem is attributed to chemical residues
found in industrial discharges, agricultural runoff, pharmaceutical waste products and new types of contaminants such as micro plastics. All of these contaminants create risks to life forms at the cellular level up to the ecosystem; from the disruption of biochemistry to the overall structure of an ecosystem. Methods: Through a systematic review and synthesis of evidence, studies from 2015 – 2024 published toxicological datasets were analyzed to create a summary report. In addition to laboratory acute toxicity assays, there were also bioaccumulation assessments and ecosystem monitoring data that were evaluated as part of the research. For example, LC₅₀, EC₅₀, BAFs and ecological quality ratios were used as standard metrics for determining effects for each of the six major contaminant classes and across multiple types of aquatic organisms. Results: Among all pesticides tested, organophosphates exhibit low LC₅₀ levels of 0.14–0.92 mg L⁻¹ demonstrating acute toxicity. Biomagnification factors for persistent organic pollutants were >10⁵ at high trophic levels. Endocrine disruptors produced reproductive dysfunction at environmentally relevant concentrations as low as 1 ng L⁻¹. Interaction of pharmaceutical residues with microplastics creates complex mixtures
resulting in toxicity levels increase by 240% compared to individual exposures. Conclusion: Improved risk assessment methods based on mixtures, bioaccumulation, and chronic exposure are needed as soon as possible. Emerging contaminants must have regulation levels that correspond with ecological information, and therefore, controls for the
source of these materials must be compatible with ecosystem-based approaches.