Vulnerability to heatwaves and implications for public health interventions – A scoping review

The worldwide increase in temperature has resulted in a marked increase in heat waves (heat extremes) that carries a markedly increased risk for morbidity and mortality. The kidney has a unique role not only in protecting the host from heat and dehydration but also is an important site of heat-associated disease. Here we review the potential impact of global warming and heat extremes on kidney diseases. High temperatures can result in increased core temperatures, dehydration, and blood hyperosmolality. Heatstroke (both clinical and subclinical whole-body hyperthermia) may have a major role in causing both acute kidney disease, leading to increased risk of acute kidney injury from rhabdomyolysis, or heat-induced inflammatory injury to the kidney. Recurrent heat and dehydration can result in chronic kidney disease (CKD) in animals and theoretically plays a role in epidemics of CKD developing in hot regions of the world where workers are exposed to extreme heat. Heat stress and dehydration also has a role in kidney stone formation, and poor hydration habits may increase the risk for recurrent urinary tract infections. The resultant social and economic consequences include disability and loss of productivity and employment. Given the rise in world temperatures, there is a major need to better understand how heat stress can induce kidney disease, how best to provide adequate hydration, and ways to reduce the negative effects of chronic heat exposure.

High-technology medicine saves lives and produces waste; this is the case of dialysis. The increasing amounts of waste products can be biologically dangerous in different ways: some represent a direct infectious or toxic danger for other living creatures (potentially contaminated or hazardous waste), while others are harmful for the planet (plastic and non-recycled waste). With the aim of increasing awareness, proposing joint actions and coordinating industrial and social interactions, the Italian Society of Nephrology is presenting this position statement on ways in which the environmental impact of caring for patients with kidney diseases can be reduced. Due to the particular relevance in waste management of dialysis, which produces up to 2 kg of potentially contaminated waste per session and about the same weight of potentially recyclable materials, together with technological waste (dialysis machines), and involves high water and electricity consumption, the position statement mainly focuses on dialysis management, identifying ten first affordable actions: (1) reducing the burden of dialysis (whenever possible adopting an intent to delay strategy, with wide use of incremental schedules); (2) limiting drugs and favouring "natural" medicine focussing on lifestyle and diet; (3) encouraging the reuse of "household" hospital material; (4) recycling paper and glass; (5) recycling non-contaminated plastic; (6) reducing water consumption; (7) reducing energy consumption; (8) introducing environmental-impact criteria in checklists for evaluating dialysis machines and supplies; (9) encouraging well-planned triage of contaminated and non-contaminated materials; (10) demanding planet-friendly approaches in the building of new facilities.

During the second half of the twentieth century, rapid demographic growth and urban expansion led to the development of the Mexico City metropolitan area (MCMA) urban heat island (UHI). The thermal gradient between rural and urban regions is used to define the UHI in the transition zone along the 268C isotherm of mean maximum temperature. As the MCMA expands, more natural vegetation is replaced with urbanization, and the spatial extent of the 268C isotherm grows. The loss of natural vegetation, in a densely populated region of Mexico, leads to the formation of a canopy-layer UHI. The intensification of the MCMA UHI results in an increase in the frequency of daily maximum temperatures above 308C (above 268C on a weekly average), a threshold value that constitutes a natural hazard. Warm-spell occurrences are related to an increase in the number of acute diarrhea diseases (ADD), mainly in zones of the MCMA where the socioeconomic and environmental conditions are low (e.g., insufficient access to potable water). Vulnerable people are mostly located in new settlements along the periphery of the MCMA, where large numbers of hospital discharges due to ADD are reported. The combined effect of more frequent warm spells and increasing vulnerability results in higher levels of risk of suffering this type of health problem, mainly during the warmest part of the year. This analysis may serve to develop UHI mitigation strategies and early warning systems to manage high levels of ADD risk during warm spells.