A recent study published in Science of The Total Environment reveals that microplastics have been contaminating freshwater ecosystems much earlier than previously believed. By examining caddisfly larvae collected from seemingly pristine streams in the Netherlands during the 1970s and 1980s, researchers discovered plastic particles embedded in the insects’ protective casings as early as 1971. This indicates that microplastics had already infiltrated freshwater environments once considered untouched, highlighting their long-standing presence in natural ecosystems.
Lead author Auke-Florian Hiemstra emphasized that the inclusion of plastics in caddisfly casings shows plastics entering the food chain. Birds and fish that consume these larvae also ingest microplastics, suggesting broader ecological impacts. The research, conducted using energy dispersive X-ray analysis to identify plastic additives within the casings, provides rare historical insights into the spread of microplastics, an area that represents less than 4% of current studies in the field.
Today, microplastics—tiny fragments between 1 micrometer and 5 millimeters—are found virtually everywhere: in clouds, food, drinking water, and even human tissues. They originate from both the breakdown of larger plastic items and intentional manufacturing for products like cosmetics. Although some larger particles can be expelled by the body, fragments smaller than 10 micrometers, and especially nanoplastics under 1 micrometer, may penetrate tissues and even pass through cell membranes. Recent research led by Matthew Campen detected nanoplastics as small as 200 nanometers in human brain tissue, raising concerns about their potential health effects.
Hiemstra’s findings expand the conversation about environmental exposure timelines. If freshwater ecosystems were contaminated with microplastics since at least the 1970s, it suggests that human populations have been exposed for much longer than assumed. This historical perspective complicates risk assessments and hints that exposure levels and health risks may have been underestimated.
Studies have linked plastics and their chemical additives, such as phthalates and PFAS, to a range of health conditions, including heart disease, lung disorders, cancer, and Alzheimer’s. However, most of these links are correlational, and the specific impact of microplastics remains under investigation. Research led by Tracey Woodruff at UCSF has documented respiratory, digestive, and reproductive health concerns associated with microplastic exposure, particularly impacts on sperm health.
Despite these emerging insights, the World Health Organization maintains that current evidence on the health effects of microplastics is limited and inconclusive. Scientists like Bernardo Lemos predict that future research will continue to uncover abundant historical evidence of microplastics in environmental and biological samples, deepening our understanding of their long-term impacts.
Given the persistence of plastics in the environment and their capacity to degrade into ever-smaller fragments, exposure will likely continue indefinitely. While awaiting further research, experts suggest reducing personal exposure by minimizing the use of ultraprocessed foods and plastic packaging.
Natural history collections, such as the caddisfly casings studied by Hiemstra, may prove crucial in establishing historical baselines for microplastics contamination. These collections offer an untapped resource for reconstructing the true environmental and health impacts of plastics over time, emphasizing the urgent need for both scientific research and policy action.