**6. Environmental Contamination by Antibiotics and One Health**

We define here 'One Health' in the context of environment and antimicrobial resistance as, One Health is a study and interpretation of an integrated paradigm of antimicrobials and antimicrobial resistance dynamics and epidemiology, that encompasses human health, biodiversity health and ecosystem health including socio-behavioural aspects, that informs on the processes leading to the occurrence and recurrence of infectious agents and resistance and their dissemination and extinction in organic and inorganic habitats/environments, for the purpose of development of antimicrobial resistance management strategies. Few studies, projects or literature reviews encompassing all these dimensions for an organism or an antimicrobial in a particular niche/geographical area/ecosystem are evident in literature (e.g., [27,29]). Studies mostly occur in separate events and not as a conscious integrated event. In our project in India entitled 'APRIAM-Studies on Antibiotic Use, Antibiotic Resistance and Antibiotic Residues in the Environment of India with a Context of Antibiotic Resistance Management in a One Health Approach', we kept in focus a One Health approach while using varying

study dimensions and while creating certain protocols [32,33]. Although the project is still ongoing, a mention of some of its results is worthwhile here to create a context between environmental antibiotic residues, antibiotic resistance, resistance genes and One Health. We found that, in people's and healthcare worker's perception, environment was intimately connected to occurrence of infectious diseases, antibiotic use and resistance development [34,35]; a time-series analysis study also showed that climatic factors influenced occurrence of Methicillin-Resistant *Staphylococcus aureus* (MRSA) skin and soft-tissue infections [36], and further we found that, resistance patterns were shared for *Escherichia coli* from humans, animal (cow) and their associated water when from an inland area, whereas, when located in the proximity of sea, resistance of *E. coli* from humans, animals and water had a shared pattern but it was different from the inland one [37]. We also found that in a niche area in a village, there was not only commonality of a resistance pattern of *E. coli* in humans, animals and the water in their environment but the commonality also extended to resistance genes [38]. In further exploration, we found that antibiotic residues, antibiotic resistance and resistance genes in water and sediments of a nearby river share some commonality [21]. As socio-behavioural and anthropogenic aspects also have an impact on the generation of resistance in the environment [39]. We also conducted studies on the same river about the impact of a special anthropogenic activity particular to India, holy dip and congregative holy dip of millions of persons in a holy river (Kumbh Mela) on antibiotic residues, antibiotic resistance and resistance genes (to be published). When our studies are complete, all these will be mapped from a One Health perspective.

#### **7. Current Wastewater Treatment Failure**

Wastewater is produced daily from various sectors and segments of society. Worldwide, 113 countries have data available on wastewater production, 103 countries on wastewater treatment, and62 countries on wastewater use [40] E ven after treatment, antibiotic residues, antibiotic resistant bacteria and resistance genes are still present in the wastewater, and the wastewater treatment plants (WWTP) are considered 'hot spots' of resistance multiplication [41] The wastewater from households, animal rearing facilities and WWTP effluents mostly get released into nearby waterways, wherefrom it might be used for irrigation purposes and studies have shown that some antibiotics have very long half-lives in agricultural soils: 55 to 578 days for tetracycline and 120 to 2310 days for ciprofloxacin [42–44]. Conventional wastewater treatment facilities typically have biological degradation, for example using the activated sludge process, whereas advanced facilities have tertiary treatment processes, such as reverse osmosis, ozonation, sonolysis and advanced oxidation technologies like fenton oxidation, heterogenous-photocatalysis with TiO2 etc. These treatments do not necessarily fully remove antibiotic residues, antibiotic resistant bacteria and resistance genes from the wastewater. For example, there are reports that antibiotic residues, antibiotic resistant bacteria and resistance genes still remain even after the conventional treatment [16,45]. Additionally, even after the advanced treatment processes currently in use, the problem is not fully resolved, for example, a study showed that even after ozonation treatment about 20% of sulfonamides, trimethoprim and macrolides still remained in the effluent [46].
