The Role of Biochar and Earthworms in Pharmaceutical Remediation of Contaminated Soil: A Systematic Review

Abstract Pharmaceutical contaminants in soils have become a critical and emerging environmental concern due to their persistence, toxicity, and potential to disrupt both ecosystems and human health. This manuscript provides a comprehensive review of current knowledge on the occurrence, contamination pathways and environmental fate of active pharmaceutical compounds in soil environments globally. The systematic review of recent literature on the topic of pharmaceutical remediation of contaminated soils through biochar and earthworms led to the final inclusion of 116 relevant articles. Based on these findings, the review evaluates sustainable bioremediation strategies that can effectively mitigate pharmaceutical contamination and support global efforts towards environmental sustainability, ecosystem resilience, and public health protection. Biochar, a low-cost, carbon-rich material derived from biomass pyrolysis, has gained significant attention for its high sorption capacity, enabling it to immobilize a broad spectrum of pharmaceutical compounds, thereby reducing their environmental toxicity. Concurrently, vermiremediation using earthworms, offers a promising approach that facilitates the degradation and removal of pharmaceuticals. Moreover, the review highlights the effectiveness of biochar, earthworms and their combined applications in remediating soils contaminated with antibiotics, non-steroidal anti-inflammatory drugs, endocrine disruptors, antihypertensives, anticonvulsants, antidepressants and other pharmaceutical classes. Unlike previous reviews, this study systematically integrates mechanisms and empirical data of biochar-earthworm synergistic remediation, quantifies remediation efficiency differences across drug types, offering new insights for sustainable soil remediation. To advance this promising field, further research is recommended to explore a wider range of pharmaceutical compounds, assess long-term environmental impacts, and optimize the synergistic effects of biochar and earthworms under diverse, real-world conditions.