Assessment of medical waste management practices and implications for antimicrobial resistance risk in urban Nigeria

Abstract Antimicrobial resistance (AMR) is a major global public health threat. Medical waste management is a potentially important but underexplored pathway for environmental dissemination of antimicrobial residues and resistant microorganisms, particularly in low- and middle-income countries. A concurrent mixed-methods study was conducted in seven healthcare facilities in Lagos State, Nigeria. Quantitative data were collected through structured questionnaires administered to 336 healthcare workers and facility assessments. Qualitative data were obtained through semi-structured interviews with 49 key informants, direct observations, and policy document reviews. Quantitative data were analysed using descriptive statistics and chi-square tests in SPSS version 26, while qualitative data were analysed thematically using NVivo 12. Mixed-methods integration occurred at the design, analysis, and interpretation stages. Medical waste generation ranged from 0.116 to 0.561 kg/bed/day across facilities. Only 61% of respondents correctly identified that waste segregation should occur at source, while only 33.3% correctly identified pharmaceutical waste colour-coding requirements. Storage durations ranged from 5–10 days, substantially exceeding WHO recommendations of 24–48 h. Pharmaceutical waste was frequently mixed with general and infectious waste streams, and no facility reported specialised treatment for antimicrobial-containing waste. Knowledge of waste categorisation varied substantially by professional category, with the highest accuracy among doctors and laboratory scientists and the lowest among domestic workers/cleaners (χ 2  = 1344.00, df = 20, p  < 0.001). Because approximately 70% of contingency table cells had expected counts below five, this association is reported as an exploratory, descriptive pattern rather than a robust inferential result throughout this manuscript. Policy analysis revealed limited integration of AMR considerations into healthcare waste management regulations and weak institutional coordination. The findings suggest that current medical waste management practices in Lagos may create conditions that facilitate environmental dissemination of antimicrobial residues and resistant microorganisms. Strengthened segregation, improved storage and treatment systems, environmental monitoring, and integrated governance approaches are required. Future studies should directly measure antimicrobial residues, resistant bacteria, and resistance genes in environmental media to validate the pathways identified in this study.