Biomarkers and bioindicators of genotoxicity assessment of solid waste emissions from India: Insights into mechanisms of its genome instability

Abstract

India’s rapid population growth positively correlates with solid waste generation. Indiscriminate disposal in unsanitary landfills is dominant, and releases hazardous contaminants, that pose genotoxic risks to humans and biota. This study evaluated DNA damage and genome instability induced by solid waste emissions of Indian origin. Following PRISMA guidelines, 36 peer-reviewed studies published until 2025 were selected. These studies reported 40 bioindicators and 56 genotoxic biomarkers, with cell lines and comet assay most frequently reported. Significant DNA strand breaks, micronucleus formation, chromosomal aberrations, nuclear abnormalities, and sperm defects in exposed models were consistently reported, often in dose- and time-dependent patterns. Random-effects meta-analysis using pooled standardized mean differences showed significant positive effect sizes for micronucleus and comet endpoints (p ≤ 0.0001), confirming increased genetic damage in exposed groups. Although substantial heterogeneity was observed (I² = 95.73% for micronucleus; 87.66% for comet), the direction of effect remained consistently positive. Risk-of-bias assessment indicated overall moderate to high methodological quality, with common reporting gaps in exposure characterization and blinding procedures. Oxidative stress and ROS generation are dominant drivers of genome instability. Signaling pathways causing DNA adduct, DNA repair impairment, epigenetic dysregulation, and mitochondrial-mediated apoptosis were other mechanisms. Despite strong evidence of somatic and germline genotoxicity, epidemiological data and quantitative exposure assessments remain inadequate. Integrated exposure monitoring, advanced molecular and epigenetic biomarkers, dose–response characterization and long-term population-level biomonitoring are needed to strengthen causal inference and human health risk assessment. Emissions from solid waste facilities in India represent a credible genotoxic hazard warranting improved waste management, and regulatory enforcement.