Clinical Trials and Environmental Sustainability

Clinical trials are central to evaluating the safety, efficacy and effectiveness of interventions intended to improve health outcomes. They also generate environmental harms. Around 76,000 new trials were registered on the World Health Organization’s International Clinical Trials Registry Platform in 2023, and each was estimated to produce between 80 and 2000 tonnes of emissions. Trials can also generate hazardous and non-hazardous waste, contribute to air pollution through travel and increase water use. Reducing these harms has become an important concern, particularly because any response needs to protect trial integrity and avoid reinforcing existing inequities in the clinical trial landscape, especially in low- and middle-income countries.

Most published work has focused on greenhouse gas emissions and has largely come from a small number of high-income countries, with limited data on how other environmental harms appear across different settings. Climate-related disruption adds another layer of pressure, as floods, heatwaves and other weather events can affect trial sites, supply chains and participant access.

Sustainability Starts Before Recruitment

Environmental considerations belong in trial design from the outset. Good-quality and well-planned trials based on rigorous methodologies reduce unnecessary and wasteful research practices. Clinical trial activity can be considered across three stages: pre-trial, in-trial and post-trial. Pre-trial activity includes design and planning, site selection, trial protocols, team preparation, funding applications, regulatory and ethics approval, and procurement and delivery of equipment or interventions.

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At this stage, trial planning can reduce environmental harms through clearer communication, better coordination and stronger local capacity. Early communication between those running the trial and proposed trial sites supports collaborative design and avoids duplication. Site selection also affects travel requirements and local infrastructure needs, so reducing long-distance travel for feasibility visits and improving local trial capacity are both important. Regulatory bodies can improve the review of trial applications by providing guidance, while funders can support mitigation strategies and include resources for low- and middle-income country trial capacity development. Ethics review boards can consider environmental harms linked to trial activities. Communication between funders, regulators and ethics review boards can also clarify expectations for environmentally and socially just trials. Other pre-trial measures include optimising logistics, reducing unnecessary packaging and reporting environmental harms associated with investigational medicinal products, equipment and supplies.

Lower-Impact Delivery During the Trial

Once the trial begins, environmental performance depends on day-to-day decisions across recruitment, meetings, storage, monitoring and data handling. In-trial activities include participant recruitment and consent, delivery of the intervention, sample and data collection, trial-specific participant assessment, protocol amendments when required, data management, quality monitoring and adverse event reporting.

Several measures can reduce harms during this stage. Staff education and awareness can improve implementation, while context-specific approaches allow trial sites to use mitigation strategies that match local conditions. Virtual meetings can replace some in-person activity when appropriate, and trial protocols can allow sites to incorporate climate and environmental mitigation strategies. Clear and early communication between those running the trial and trial sites can support efficient participant recruitment. Maximal retention and adherence can also reduce waste by limiting avoidable repetition and incomplete processes. The same principle applies to sample and data collection. Sufficiency means collecting and analysing only what is required to answer the research question. Review appraisals can therefore require justification for central processing and storage of samples. Additional measures include reducing travel, warming ultra-low-temperature freezers when feasible, reducing on-site data monitoring and in-person audits where possible, and using green algorithms in data processing.

Resilience and Post-Trial Responsibilities

Climate resilience also needs attention across trial systems. Clinical trials can face disruption from flooding, heatwaves and other weather events that block access to sites or interrupt cold chains and the delivery of biological samples, drugs and medications. These vulnerabilities are especially relevant in low- and middle-income countries, which often face greater exposure to climate impacts and have fewer resources to protect against them. Underserved areas in upper-middle-income countries and high-income countries can also face similar risks. A just response places environmental and social justice at the centre of trial development and applies the same principle to adaptation strategies.

Adaptation measures cover planning and governance, clinical trial facilities, trial participants and supply chains. Regulatory authorities can strengthen resilience through agility and flexibility. Funding decisions can include climate resilience as a routine consideration. Ethics review boards can help protect participant safety in sites with climate vulnerabilities, and trial designers can consider climate risks when choosing sites and developing emergency protocols. Trial facilities can prepare through vulnerability awareness, routine infrastructure checks, links with wider climate adaptation plans, staff training, effective emergency protocols, renewable energy systems and paperless data management systems. Participant protection can rely on contingency protocols for locating and contacting participants and for meeting trial-related medical needs while preserving trial integrity where possible. Supply chains can prepare through risk and vulnerability assessments at every stage, supported by contingency planning and the reuse, recycling and repair of trial supplies.

Post-trial activity also carries environmental responsibilities. These include reducing plastic waste, repurposing or repairing equipment, repurposing investigational medicinal products to local pharmacies where possible, using responsible recycling and disposal of electronic waste, applying sufficiency to long-term sample storage, supporting findability, accessibility, interoperability and reuse in data and sample management, adapting the length of paper archiving to risk level, disposing of paper documents responsibly, requiring environmental consideration disclosures in publications and ensuring timely reporting of findings, including environmental impacts.

Environmental sustainability and climate resilience run through the full life cycle of clinical trials. Trial quality, trial integrity, local capacity and environmental responsibility are closely connected. Better planning can reduce waste before recruitment starts. Operational changes during trial delivery can reduce travel, storage burdens and unnecessary data collection. Stronger adaptation planning can help sites, participants and supply chains cope with climate-related disruption. A more just clinical trial model depends on combining these measures without shifting burdens onto settings with fewer resources.

Source: World Health Organization

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