Attention to environmental AMR in the context of measures to combat AMR based on the One Health approach should focus on the risks posed by environmental water deemed to have been contaminated with antimicrobialresistant bacteria and on the assessment of those risks. It is currently difficult to set concrete benchmarks for discussing these risks, because only a very few studies have, to date, quantitatively evaluated the risks thus posed and the Japanese government has not conducted ongoing assessment. However, countries around the world have reported a series of cases in which antimicrobial-resistant factors have been detected not only in hospitals, communities and food-producing animals, but also in the environment (e.g. soil and rivers). For instance, marked contamination of the environment by antimicrobials has occurred in an area on the outskirts of an Indian city that is home to plants that manufacture generic for the global market, with concerns reported about environmental pollution and the emergence of antimicrobial-resistant bacteria due to selective pressure caused by the antimicrobials discharged. The contamination of vegetables believed to result from the use of river water for irrigation  and assessments of the risk of exposure through water-based recreation  are starting to be reported, albeit only little by little. Given reports such as the isolation of carbapenem-resistant Enterobacteriaceae at one of the aquatic venues for the Rio de Janeiro Olympics, the situation appears to have reached a stage at which the risks of exposure should be accurately evaluated.
With the support of the WHO, the Global Sewage Surveillance Project  is being conducted with the involvement of 90 countries. Japan has already provided samples and the results are awaited. A research group funded by a Ministry of Health, Labour and Welfare research grant has been formed to conduct a more detailed evaluation of the situation in Japan in parallel with this project. Led by Hajime Kanamori, the research group will conduct a study entitled “Research to Establish Methods of Surveying Antimicrobial-resistant Bacteria and Antimicrobials in the Environment” from 2018 to 2020. Prior to the formation of the research group, nextgeneration sequencers were used to establish a comprehensive technique for sequencing antimicrobial resistance genes (metagenomic analysis) in environmental water (Pathogen Genomics Center, National Institute of Infectious Diseases). During the first year of the study (FY2018), the group plans to obtain and analyze samples of wastewater from 27 local governments to identify characteristics of AMR based on population, as well as local and industrial features.
Information on the situation within Japan is starting to emerge, such as a report on the isolation of carbapenemase-producing Enterobacteriaceae at sewage treatment plants in both Japan and Taiwan and the clarification of its genomic information, as well as a report on the isolation from a site in Tokyo Bay of a KPC-2-positive Klebsiella pneumoniae strain, which is rarely found in Japan, even in clinical isolates. As in the case of the contamination situation overseas, a more extensive field survey would appear to be required in Japan, at least to ascertain the true extent of the isolation of antimicrobial-resistant bacteria in environmental water. Global efforts to link field surveys into risk assessment are expected to be accelerated globally, through such initiatives as the workshop for the Joint Programming Initiative on Antimicrobial Resistance (JPIAMR)  held in September 2017 to assess the risk posed to human health by such antimicrobial-resistant bacteria in the environment.
In the area of health care associated infections, field epidemiology and molecular epidemiological analysis of isolated strains have, thus far, been used for identifying modes of transmission and quantifying the risk of health effects. However, as described above, research findings indicating that antimicrobial-resistant bacteria derived from the environment affect human and animal health are scarce. Accordingly, there are no established opinions on whether the extent of antimicrobial resistance in the environment may pose health risks, so challenges for the future include not only undertaking systematic reviews of the main body of literature and building up studies that enable the health risks to be evaluated, but also enhancing testing by local governments via local public health institutes and the like.