Combined Chemical Exposures and Synergistic Toxicity: Unraveling Biochemical Interactions in the Anthropocene
Kungu Erisa
Faculty of Pharmacy Kampala International University Uganda
Email: erisa.kungu@studwc.kiu.ac.ug
ABSTRACT
Human and ecological systems in the Anthropocene are exposed to complex mixtures of chemicals from industrial, agricultural, pharmaceutical, and consumer-product sources. These combined exposures frequently produce effects that are not predicted by single-chemical toxicology: interactions can be additive, antagonistic, or synergistic, with synergy posing the greatest concern because low-level co-exposures may produce unexpectedly large adverse outcomes. This review synthesizes mechanistic knowledge of mixture toxicity with an emphasis on biochemical interactions that drive synergy. We examine key interaction modalities – competitive and noncompetitive enzyme inhibition, receptor co-activation and cross-talk, redox cycling and oxidative stress amplification, disruption of detoxification pathways and transporters, endocrine network interference, and microbiome-mediated biotransformation. Methods for assessing mixture effects are evaluated, including experimental designs (fixed-ratio and factorial mixtures), dose–response modelling (concentration addition, independent action, response-surface methods, isobolograms), and emerging in vitro, in vivo, and in silico tools (high-throughput screening, organoids, PBPK-toxicodynamic models, systems toxicology). We discuss biomarkers and multi-omics strategies for detecting synergistic biochemical perturbations and highlight illustrative case examples where co-exposures intensify risk (e.g., pesticide combinations, metal–organic pollutant interactions, polypharmacy and environmental contaminants). Critical challenges are identified: exposure characterization, realistic dose metrics, non-monotonic and low-dose effects, interindividual variability, and regulatory frameworks that still largely rely on single-chemical assessment. The review concludes with research priorities to improve prediction and prevention of synergistic toxicity, advocating integrated experimental–computational pipelines, standardized mixture reference materials, human-relevant models, and policy adaptations that account for cumulative and interaction-driven risks.
Keywords: mixture toxicity, synergy, oxidative stress, pharmacokinetic interactions, systems toxicology
CITE AS: Kungu Erisa (2026). Combined Chemical Exposures and Synergistic Toxicity: Unraveling Biochemical Interactions in the Anthropocene. IAA Journal of Applied Sciences 14(1):90-97.