## 5 Determining the Safety of _E. coli_ O157:H7 Specific Bacteriophages as a Biocontrol Agent  
To maximise the potential of phage treatment of _E. coli_ O157:H7 infections, phage candidates must be safe and capable of serving as biocontrol agents without having negative effects on people or the environment. Firstly, phage's specificity for _E. coli_ O157:H7 must be ensured by isolating and properly characterising candidate phage; afterwards, phages should be screened for the existence of genes linked to virulence and antibiotic resistance within the phage's genome simply because genes that encode toxins and allergens must not be present in phages intended for biocontrol as they can be detrimental to humans and animals [108]. New generation sequencing techniques like the Whole Genome Sequencing (WGS) can be used to analyse the phage genome and determine the presence of these genes. WGS is a method of typing that relies on sequencing of the entire genome of an isolate, allowing for the identification of variations at the level of individual nucleotides [157]. Based on the findings of the study conducted by [PERSON] et al. [158], WGS was used to determine the absence of virulence factors, toxins, antibiotic resistance, and potential allergen-coding genes in the genome of the isolated phage KFS-EC. The phage which was obtained from wastewater samples from a slaughterhouse in Korea exhibits specificity exclusively towards _E. coli_ O157:H7 and was considered to be suitable as a biocontrol agent. In addition, as described by [PERSON] et al. [159], WGS can be used to determine the presence of lysogenic elements that may potentially enable the dissemination of undesirable genes among bacterial communities. Having confirmed the lack of such elements, the phages can then be considered to be safe for use as a biocontrol. It is vital to highlight that WGS supports the \"One Health\" concept, which considers the interrelated nature of human, animal, and environmental health. This is demonstrated by the impact WGS has on public health responses, as its usage can quickly pinpoint the safety of phage candidates and support the implementation of efficient control measures to stop the spread of antimicrobial resistant microbes [160]. Having considered the genomic screening of phages, conducting animal studies to assess the safety of the phages in the target host organisms (e.g., livestock) is essential before a large scale production. Studies on the effectiveness of phages in treating experimentally infected animals [161; 162] have demonstrated that using mice, chickens, or sheep in biocontrol trials will allow for the monitoring of any negative effects on animal health [163]. Clinical trial studies can evaluate the safety of phage therapy in people, including possible allergic reactions or other adverse effects. They can also determine the right concentration and dosage of phages required to control _E. coli_ O157:H7 in people. Due to the sensitive nature and ethical issues associated with phage application, stakeholders like farmers, food processors, and healthcare professionals should obtain training on how to handle phages safely and responsibly in the real-world settings. Furthermore, while ensuring phage purity and quality during preparation, there is a possibility of generated residues and contaminants causing environmental hazards, which could pose a health risk. It is crucial to monitor the potential environmental impact of using phages, such as phage persistence in the environment and potential ecological disruptions. In the event that genetic modifications in the host bacterium impart phage resistance, such phages are not suitable for use as a biocontrol. Therefore, phage safety concerns require constant monitoring and surveillance.