Linking Environmental Antimicrobial Resistance to Human Health: Pathways, Co-Selective Pressures and Attribution Gaps.

Antimicrobial resistance (AMR) is recognised as a significant global health threat, yet research, surveillance and intervention strategies remain largely focused on clinical and veterinary settings, with limited attention to environmental reservoirs and transmission pathways. Growing global evidence, including from Aotearoa New Zealand (NZ), points to a clear link between dominant sources of AMR entering the environment (such as wastewater) and its dissemination in receiving environments. Once in these environments, a wide range of microorganisms, both environmental and introduced, interact in complex ways, with their associated resistomes contributing to potential human exposure pathways. However, clear attribution of environmental AMR contributions to human (and animal) health outcomes remains limited and represents a critical next step for research and surveillance. This viewpoint highlights global and regional evidence on environmental contributions to AMR transmission and dissemination, with emphasis on co-selective pressures including antibiotics, heavy metals, biocides and plastics that promote resistance selection, persistence and horizontal gene transfer. We identify key gaps in NZ, notably the lack of integrated, cross-sector monitoring, robust attribution approaches and quantitative assessment of risks to human health. We conclude that effective mitigation requires integrated cross-sector frameworks linking environmental surveillance, genomic data, microbial source attribution and quantitative risk assessment to inform targeted, risk-based interventions. These interventions need to be based on a deeper understanding of the interactions between environmental reservoirs, co-selective pressures and the key drivers and pathways of AMR, including broader environmental influences such as co-contaminants and climate change.