Pharmaceutical residues and chemicals in landfill leachate from a sanitary landfill in Malaysia: non-target analysis and records of health and environmental hazards.

Pharmaceutical residues (PRs) and pharmaceutical chemicals (PCs) have been detected in landfill leachate though landfill sites have no direct role in managing pharmaceutical wastes. However, their detailed exploration is still challenging in leachate samples due to their vast array of metabolites and complex interactions. The present study is aimed to perform a non-target analysis of PRs and PCs in leachate from a sanitary landfill in Malaysia. Cross-sectional study of total 28 samples was conducted at Jeram Sanitary Landfill at Selangor, Malaysia, from July 2023 to October 2023. Grab sample of fresh untreated leachate was collected in a borosilicate glass bottle near leachate collection pond. The centrifuged supernatant liquid was analyzed with LCMS-QTOF system. The chromatographic profiles were analyzed based on mass data, and the compounds were annotated using METLIN database. A total of 7125 PRs and PCs were detected, out of which 1,288 were PRs (mean ± SD 46.00 ± 35.70) and 5837 were PCs (mean ± SD 208.46 ± 102.38). There were 1862 (25.6%) cases of health hazards, and 212 (3.0%) cases of environmental hazards caused by various PRs. Similarly, leachate was laden with various PCs that could cause 2417 (33.7%) cases of health hazards, and 312 (4.4%) cases of environmental hazards. These health hazards were caused by various mechanisms such as toxicity, hypersensitivity, neurotoxicity, carcinogenicity and other. Similarly, environmental hazards were mediated by ecotoxicity, persistence and biomagnification. The results showed the dire scenario of PRs and chemicals in leachate. This implies that urgent interventions be instituted in waste segregation and disposal of people and healthcare facilities to restrict entry of pharmaceutical products and chemicals into non-hazardous waste landfill without prior stabilization.