Distribution and risk assessment of microplastic pollution in a rural river system near a wastewater treatment plant, hydro-dam, and river confluence

Research published in the journal Scientific Reports discusses the ways microplastics enter riverine systems. The study focuses on the rural Raquette River, in New York, and evaluates distinct locations where microplastic may enter the river. The highest microplastic concentrations were found mostly downstream of a wastewater treatment plant, upstream of the hydro-dam, and in the river confluence.

Abstract: Rivers are the natural drainage system, transporting anthropogenic wastes and pollution, including microplastics (plastic < 5 mm). In a riverine system, microplastics can enter from different sources, and have spatial variance in concentration, physical and chemical properties, and imposed risk to the ecosystem. This pilot study presents an examination of microplastics in water and sediment samples using a single sample collection from the rural Raquette River, NY to evaluate a hypothesis that distinct locations of the river, such as downstream of a wastewater treatment plant, upstream of a hydro-dam, and river confluence, may be locations of higher microplastics concentration. In general, our results revealed the presence of high microplastic concentrations downstream of the wastewater treatment plant (in sediments), upstream of the hydro dam (both water and sediment), and in the river confluence (water sample), compared to other study sites. Moreover, the risk assessment indicates that even in a rural river with most of its drainage basin comprising forested and agricultural land, water, and sediment samples at all three locations are polluted with microplastics (pollution load index, PLI > 1; PLIzone = 1.87 and 1.68 for water and sediment samples respectively), with risk categories between Levels I and IV (“minor” to “danger”). Overall, the river stands in a “considerable” risk category (PRIzone = 134 and 113 for water and sediment samples respectively). The overall objective of this pilot study was to evaluate our hypothesis and advance our understanding of microplastic dynamics in rural river systems, elucidating their introduction from a point source (wastewater treatment plant), transit through an impediment (hydro-dam), and release into a vital transboundary river (confluence of Raquette-St. Lawrence Rivers).

Atmospheric pollution includes microplastics. A team of researchers from Cornell University have determined that the shape of microplastics play a key role in how they travel. Using a model to simulate the atmospheric transportation of microplastic fibers has shown that common flat fibers travel farther in the lower atmosphere than spherical shaped fibers.

“We can now more accurately attribute the sources of microplastic particles that will eventually be transported to the air,” lead author Qi Li said. “If you know where they’re coming from, then you can come up with a better management plan and policies or regulations to reduce plastic waste. This could also have implications for any heavy particles that are transported in the lower atmosphere, like dust and pollen.”

In a scientific statement, the American Heart Association lays out its concerns about the adverse health consequences caused by exposures to environmental toxicants and pollutants, and cardiovascular diseases in young people. The article provides evidence that connects climate change and congenital heart disease, airborne pollution and Kawasaki disease, blood lead and blood pressure, endocrine-disrupting chemicals and cardiometabolic risk factors, perfluoroalkyl and polyfluoroalkyl substances, and other sources of pollution to adverse childhood health effects, especially relating to heart health.

Scientists find that interlocking and dismantling popular plastic toy building bricks generate microplastics and nanoplastics. These plastic fragments may pose a health risk to children who play with the bricks.

Abstract: Microplastics and nanoplastics have become noteworthy contaminants, affecting not only outdoor ecosystems but also making a notable impact within indoor environments. The release of microplastics and nanoplastics from commonly used plastic items remains a concern, and the characterisation of these contaminants is still challenging. This study focused on evaluating the microplastics and nanoplastics produced from plastic building bricks. Using Raman spectroscopy and correlation analysis, the plastic material used to manufacture building blocks was determined to be either acrylonitrile butadiene styrene (correlation value of 0.77) or polycarbonate (correlation value of 0.96). A principal component analysis (PCA) algorithm was optimised for improved detection of the debris particles released. Some challenges in microplastic analysis, such as the interference from the colourants in the building block materials, was explored and discussed. Combining Raman results with scanning electron microscopy – energy-dispersive X-ray spectroscopy, we found the scratches on the building blocks to be a significant source of contamination, estimated several thousand microplastics and several hundred thousand nanoplastics were generated per mm2 following simulated play activities. The potential exposure to microplastics and nanoplastics during play poses risks associated with the ingestion and inhalation of these minute plastic particles.

Microplastics are reservoirs for microbial communities. Scientists are finding that microbes associated with microplastics tend to have biocidal-, metal-, and antibiotic-resistant genes. This “plastiome” could perpetuate harmful antibiotic resistant genes in microbes in the environment. Scientists assess microbial communities on plastics in two rivers near Tokyo, Japan.

Abstract: Aquatic microplastics (MPs) act as reservoirs for microbial communities, fostering the formation of a mobile resistome encompassing diverse antibiotic (ARGs) and biocide/metal resistance genes (BMRGs), and mobile genetic elements (MGEs). This collective genetic repertoire, referred to as the “plastiome,” can potentially perpetuate environmental antimicrobial resistance (AMR). Our study examining two Japanese rivers near Tokyo revealed that waterborne MPs are primarily composed of polyethylene and polypropylene fibers and sheets of diverse origin. Clinically important genera like Exiguobacterium and Eubacterium were notably enriched on MPs. Metagenomic analysis uncovered a 3.46-fold higher enrichment of ARGs on MPs than those in water, with multidrug resistance genes (MDRGs) and BMRGs prevailing, particularly within MPs. Specific ARG and BMRG subtypes linked to resistance to vancomycin, beta-lactams, biocides, arsenic, and mercury showed selective enrichment on MPs. Network analysis revealed intense associations between host genera with ARGs, BMRGs, and MGEs on MPs, emphasizing their role in coselection. In contrast, river water exhibited weaker associations. This study underscores the complex interactions shaping the mobile plastiome in aquatic environments and emphasizes the global imperative for research to comprehend and effectively control AMR within the One Health framework.

While evidence of microplastics and nanoplastics in the human body is well-established and growing, research that can help us understand the actual effects of these plastic particles on our health is just getting underway. Much more research is needed to understand the full range of consequences of plastic particles in our bodies and their impacts on our health.

One of the first studies attempting to understand such impacts assessed potential links between the presence of microplastics in carotid artery plaques of patients undergoing heart surgery and heart disease. Scientists found polyethylene (PE) particles in the hearts of more than 58% of the 257 patients studied and followed up with. More than 12% of patients had polyvinyl chloride (PVC) particles in their arterial plaques. The patients with microplastics detected in their plaques also showed signs of inflammation in their bodies, and were much more likely to go on to experience heart attack, stroke, and death from any cause compared to patients without evidence of microplastics traveling to their hearts.

Background: Microplastics and nanoplastics (MNPs) are emerging as a potential risk factor for cardiovascular disease in preclinical studies. Direct evidence that this risk extends to humans is lacking.