Medical Imaging Contrast Agents Linked to Growing Environmental Concerns
Medical imaging procedures utilizing contrast media may be contributing to significant environmental pollution, according to new research published online December 5 in JAMA Network Open. A study quantifying the use of these agents reveals a substantial and increasing volume entering wastewater systems, potentially impacting rivers, oceans, and even drinking water supplies.
Researchers, led by Florence X. Doo, M.D., from the University of Maryland in Baltimore, sought to understand the scale of contrast agent usage as it relates to the broader “triple planetary health crisis”—the interconnectedness of human health, environmental sustainability, and social justice. Their analysis leveraged U.S. Medicare Part B claims data from 2011 to 2024 to estimate national trends in procedures utilizing contrast for both computed tomography (CT) and magnetic resonance imaging (MRI) scans.
Millions of Contrast-Enhanced Exams Annually
The study found that Medicare beneficiaries underwent an estimated 169.3 million contrast-enhanced examinations between 2011 and 2024, encompassing 82 different medical codes. These procedures required approximately 13.5 billion mL of contrast media. The majority – 50 percent – utilized iodinated agents, primarily in CT and angiography (CTA) scans, while the remaining 50 percent employed gadolinium-based agents for MRI and magnetic resonance angiography (MRA).
Specifically, iodinated agents accounted for 95.6 percent of the total contrast volume. CT scans of the abdomen or pelvis were the single largest contributor, accounting for 4.4 billion mL out of a total of 12.9 billion mL of iodinated contrast used. Brain MRI procedures led the consumption of gadolinium agents, utilizing 221 million mL.
Rising Usage, Post-Pandemic Rebound
Overall, the annual volume of contrast used increased steadily from 2014 to 2019, with a mean year-over-year growth rate of 5.2 percent for iodinated agents and 3.5 percent for gadolinium agents. The COVID-19 pandemic caused a temporary decline in usage in 2020, but the data shows a return to pre-pandemic levels, with normalization observed from 2022 through 2024.
“Contrast agents are necessary for effective imaging, but they don’t disappear after use,” a senior researcher stated. “Iodine and gadolinium are non-renewable resources that can enter wastewater and accumulate in rivers, oceans, and even drinking water.”
The researchers emphasize that quantifying which imaging exams utilize the most contrast is crucial for developing effective contrast stewardship strategies. These strategies aim to ensure patients continue to receive safe and high-quality imaging care while minimizing the environmental impact of these essential medical tools.
