The 142nd HGPI Seminar, we welcomed Dr. Kei Nagai, an Associate Professor at the Institute of Medicine, University of Tsukuba, who serves as a nephrologist at the forefront of clinical care at Hitachi General Hospital. As the Chair of the Green Dialysis Working Group of the Japanese Association of Dialysis Physicians, Dr. Nagai is a leading figure in Japan championing sustainability in healthcare. Centered on the theme of World Kidney Day 2026, “Kidney Health for All – Caring for People, Protecting the Planet,” the seminar featured a detailed presentation on the profound connection between kidney disease policy and planetary health. Dr. Nagai also discussed the necessary transformations in clinical practice, drawing on the latest research data, including Life Cycle Assessment (LCA).

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• The Alarming Reality of Chronic Kidney Disease (CKD) and the Biological Vulnerability of the Japanese Population: The number of CKD patients in Japan has reached approximately 20 million, making it a “national disease” that affects one in five adults. Research indicates that Japanese individuals are born with a smaller number of nephrons (the functional units of the kidney) compared to other ethnic groups. This biological vulnerability places the population at a higher risk of progressing to severe kidney failure due to lifestyle-related factors such as high salt intake.
• Significant Impact on Healthcare Economics: The annual treatment cost for a single patient with end-stage kidney disease ranges from 4 to 6 million yen. Total national dialysis expenditures are estimated at approximately 1.6 trillion yen, representing a substantial portion of the national social security budget.
• The Massive Environmental Burden of Dialysis Care: Hemodialysis (HD) is highly resource-intensive, requiring over 120 liters of purified water per session alongside significant energy and single-use materials. Life Cycle Assessment (LCA) calculations show that in-center hemodialysis in Japan generates a carbon footprint of approximately 4.1 t-CO2eq per person per year. This environmental impact is roughly 20 times that of the average healthcare patient.
• The Hidden Environmental Impact of “Medicine”: Analysis of environmental load factors—including logistics, water, electricity, medical materials, and pharmaceuticals—revealed that “medicine” represents the single largest contributor. This holds true for both greenhouse gas emissions (Carbon Footprint) and water consumption (Water Footprint), primarily due to resource-intensive manufacturing and distribution processes.
• “Preservation of Kidney Function” as the Ultimate Goal of Green Nephrology: The environmental footprint of a patient increases more than tenfold once they transition to dialysis care compared to those in the pre-dialysis stage. Therefore, protecting kidneys through early detection and disease management is the most effective way to protect the future of our planet.
• Mitigating the Burden on Healthcare Professionals through Institutional Incentives: Integrating environmental considerations into clinical practice must not rely solely on the passion of healthcare staff. Discussions regarding institutional frameworks, such as healthcare reimbursement incentives to facilitate the hiring of additional personnel, are essential to offset the operational burden in already busy medical environments.

Evolution of the Kidney and the “Silent Organ”: Biological Inequity Affecting the Japanese Population

The kidney emerged approximately 500 million years ago during the evolutionary transition of life from sea to land, developing as a sophisticated system for maintaining homeostasis by conserving and recycling water and salt. Each pair of kidneys contains approximately two million nephrons—the functional units composed of glomeruli responsible for filtration and tubules responsible for reabsorption—which continuously filter blood to maintain a stable internal environment.

However, the kidney is often referred to as a “silent organ” because noticeable symptoms rarely appear until its function has significantly declined. As a result, early detection through simple screening methods, such as urinalysis, is critically important. In Japan, the number of patients with chronic kidney disease (CKD) is estimated to be approximately 20 million and continues to increase alongside population aging.

Of particular importance is the biological disparity in kidney structure and capacity across populations. Research suggests that Japanese individuals tend to be born with fewer nephrons compared with some other populations, which may result in relatively lower renal reserve. Consequently, lifestyle-related factors such as excessive salt intake and hypertension may place greater strain on renal function and can lead to kidney failure at an earlier stage. This biological vulnerability underscores the importance of strategic early detection and intervention.

Uncovering the Environmental Burden of Dialysis Care Through Life Cycle Assessment (LCA)

Dialysis, a renal replacement therapy for end-stage kidney disease, is an indispensable technology that sustains patients’ lives. At the same time, however, it consumes substantial economic and environmental resources. Economically, dialysis treatment costs approximately 4–6 million yen per patient per year, with total national expenditures reaching roughly 1.6 trillion yen annually.

From an environmental perspective, dialysis care can be characterized as a resource-intensive form of healthcare, requiring large volumes of water and energy while generating significant amounts of medical waste. Dr. Nagai quantified these complex burdens using Life Cycle Assessment (LCA), a methodology that evaluates environmental impacts across the entire lifecycle—from raw material procurement and manufacturing to use and disposal.

The analysis showed that the Carbon Footprint of Products (CFP)—which quantifies greenhouse gas emissions across the lifecycle of a product or service in carbon dioxide equivalents (CO₂eq)—for in-center hemodialysis (HD) in Japan reaches approximately 4.1 t-CO₂eq per patient per year. This figure substantially exceeds the approximately 2.6 t-CO₂eq associated with peritoneal dialysis (PD) performed at home.

Another important perspective is the Water Footprint (WFP), which evaluates the volume of “hidden water” embedded throughout production and service processes.

Notably, pharmaceuticals were found to have a particularly large impact across both indicators. Patients with kidney failure often require multiple prescription medications, and the environmental burden associated with manufacturing and distributing a single tablet or injection can exceed the direct consumption of electricity and water at dialysis facilities. This finding introduces a new dimension to ongoing discussions on “green dialysis”, highlighting the importance of supply chain management in reducing the overall environmental impact of dialysis care.

Ensuring Resilience and Addressing the Vulnerability of Dialysis Care During Disasters

Dialysis care, which requires large volumes of water and electricity, is highly vulnerable to infrastructure disruptions during disasters. The Great Hanshin-Awaji Earthquake revealed severe damage to water piping systems as a critical challenge, while the Great East Japan Earthquake caused widespread power outages and water supply disruptions, compounded by the extreme circumstances of mass evacuations following the nuclear accident.

Reflecting on the fear experienced while managing on-site operations during the landfall of a massive typhoon, Dr. Nagai emphasized the importance of community-based disaster preparedness.

To address this challenge, efforts to measure the actual power consumption of dialysis consoles and optimize operational settings can directly contribute to maintaining life-sustaining care under conditions of energy constraints.

By adjusting dialysate volume and temperature, it has been shown that electricity consumption can be significantly reduced while maintaining the quality of care. Initiatives for “green dialysis” are therefore more than environmentally conscious activities; they form a critical foundation for healthcare resilience, enhancing the capacity of dialysis systems to adapt to resource scarcity and emergency situations.

Implementation in Clinical Practice and Business Model Transformation: From the SDGs to Nature Positive

Promoting environmentally sustainable healthcare inevitably entails challenges such as increased staff workload and additional costs. Measures such as rigorous waste segregation and the transition to peritoneal dialysis (PD)—which is estimated to require roughly ten times more effort from healthcare providers than in-center dialysis—demand considerable labor and operational adjustments.

Achieving sustainable transformation requires not only institutional incentives, such as appropriate healthcare reimbursement policies, but also a shift in business models across the entire healthcare industry.

Globally, frameworks such as the Sustainable Development Goals (SDGs), ESG (Environmental, Social, and Governance) investing, the circular economy—which treats waste as a resource—and Nature Positive, an approach aimed at restoring natural capital, are increasingly becoming fundamental principles for business.

The healthcare sector must therefore move beyond simply treating disease and instead pursue co-benefits—simultaneously reducing environmental impact while improving health outcomes.

Establishing a platform in which pharmaceutical and medical device companies disclose detailed environmental impact data under common evaluation standards would represent an essential step toward accelerating evidence-based discussion and real-world implementation.

Multilayered Collaboration and Policy Frameworks for Sustainable Kidney Care

To accelerate real-world implementation, active engagement not only from medical institutions but also from pharmaceutical companies and medical device manufacturers is essential.

At present, detailed environmental impact data for individual pharmaceuticals remain largely opaque. Therefore, it is an urgent priority to establish common evaluation standards grounded in environmental science and to develop a platform through which companies can disclose objective data that enable transparent comparison and analysis.

Furthermore, raising social awareness through engagement with patients and the public is equally important.

The slow adoption of peritoneal dialysis (PD) in Japan and the extremely low rate of deceased donor kidney transplantation—0.01 per million population in Japan compared with 18.80 in the United States—are not merely technical or clinical challenges. Rather, they reflect deeper issues related to social consensus and institutional frameworks.

Based on initiatives such as the “Palliative Care Guidance for Kidney Failure”, issued in September 2025 through collaboration among major academic societies, it is also important to appropriately present Conservative Kidney Management (CKM) as a key option for future kidney care.

This approach respects Quality of Life (QOL) while potentially reducing environmental burden, and emphasizes not only prolonging life but also enabling patients to live in a way that reflects their values, satisfaction, and sense of fulfillment.

Future Outlook

The homeostasis maintained by the human kidney and the sustainability of the global environment share a common conceptual foundation.

In this sense, the ultimate vision of “Green Nephrology” can be expressed through the philosophy that saving the kidney in front of us today ultimately contributes to safeguarding the future of the planet.

Looking toward the achievement of sustainability goals by 2030, stakeholders are expected to utilize data-driven visualization grounded in scientific evidence as a foundation for deepening dialogue among academic societies, industry, policymakers, and patient organizations.

Through such collaboration, the co-creation of next-generation healthcare policies that simultaneously advance human health and planetary protection will remain a central objective.

[Event Overview]

• Speaker: Dr. Kei Nagai (Associate Professor, Institute of Medicine, University of Tsukuba / Nephrologist)
• Date & Time: Tuesday, March 10, 2026, 16:00-17:15
• Format: Online (Zoom webinar)
• Language: Japanese
• Participation Fee: Free
• Capacity: 500 participants

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■Profile:

Dr. Kei Nagai (Associate Professor, Institute of Medicine, University of Tsukuba)

Dr. Nagai is a nephrologist and clinical researcher specializing in chronic kidney disease (CKD) and dialysis medicine. He also serves as Chief of Nephrology at Hitachi General Hospital and as Associate Professor at the Hitachi Collaborative Education and Research Center, University of Tsukuba Hospital, where he works to bridge regional healthcare, clinical education, and academic research. In addition to his longstanding work in CKD and dialysis research, Dr. Nagai has recently focused on environmentally sustainable kidney care, widely known as Green Nephrology and Green Dialysis. His work includes evaluating and reducing the environmental impact of dialysis therapy, such as water use, energy consumption, and medical waste. As Chair of the Green Dialysis Working Group under the CKD Countermeasures Subcommittee of the Japanese Association of Dialysis Physicians, he leads discussions aimed at practical implementation in clinical settings. Since August 2024, he has also served as a Visiting Researcher in the Resource Circulation Division at the National Institute for Environmental Studies, promoting interdisciplinary research that connects healthcare with resource efficiency and environmental sustainability. In addition, he contributes to the development of clinical guidelines as a member of the CKD Guideline Committee of the Japanese Society of Nephrology.

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