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Papers
317 resultsShowing papers from University of Toronto
ClearWhat is known and unknown about the effects of plastic pollution: A meta‐analysis and systematic review
This meta-analysis and systematic review pools data from hundreds of studies to assess whether plastic pollution, both large pieces and microplastics, poses a real ecological threat. The findings confirm negative effects on wildlife across many species and environments, underscoring that plastic pollution is not just an aesthetic problem but a genuine risk to ecosystems and the food chains humans rely on.
Risk-based management framework for microplastics in aquatic ecosystems
This meta-analysis pooled data from 21 toxicity studies to create a risk management framework for microplastics in water. The researchers identified specific concentration thresholds where microplastics begin to harm aquatic life — either by diluting their food supply or by particles entering their tissues. This framework could help regulators set pollution limits to protect ecosystems and, ultimately, human food sources.
The Known and Unknown: Investigating the Carcinogenic Potential of Plastic Additives
A comprehensive analysis of 2,712 known plastic additives found that over 150 are already classified as carcinogenic, while roughly 90% have never been tested for cancer-causing potential. Both the known carcinogens and the untested additives affected similar biological pathways related to DNA damage, immune response, and cancer, suggesting the true cancer risk from plastics may be significantly underestimated.
An Atmospheric Chemistry Perspective on Airborne Micro- and Nanoplastic Particles
This perspective paper highlights that airborne micro- and nanoplastics are an understudied form of air pollution that undergoes chemical changes in the atmosphere, potentially making the particles more harmful when inhaled. The authors call for atmospheric scientists and microplastic researchers to work together to better understand health risks from breathing in these particles.
Paint: a ubiquitous yet disregarded piece of the microplastics puzzle
This review found that microplastics from paint and coatings are a largely overlooked but major source of plastic pollution, with concentrations reaching up to 290,000 particles per kilogram of sediment near painted surfaces. Paint microplastics come from buildings, cars, boats, and industrial infrastructure. Of the toxic effects tested, 66% showed significant harm to organisms, particularly from antifouling paints, yet very few studies have examined this pollution source.
Microplastics in marine mammal blubber, melon, & other tissues: Evidence of translocation
Scientists found microplastics in the blubber, melon (a fatty organ in the head), and other deep tissues of marine mammals -- not just in their stomachs. This is the first evidence that ingested microplastics can move from the gut into internal organs in marine mammals, likely aided by the animals' lipid-rich tissues. Since marine mammals sit at the top of the food chain, this demonstrates how microplastics can accumulate and spread through an entire ecosystem, including into seafood consumed by humans.
Evidence of Microplastic Translocation in Wild-Caught Fish and Implications for Microplastic Accumulation Dynamics in Food Webs
Researchers found microplastics not just in the stomachs but also in the muscle tissue and livers of wild-caught fish from a Canadian lake, confirming that microplastics can move from the gut into other body tissues. Interestingly, smaller fish had more translocated particles per gram of body weight than larger fish, and there was no clear pattern of microplastics building up at higher levels of the food chain. The study highlights that people eating fish fillets may be consuming microplastics that have moved beyond the gut into edible tissue.
Maternal exposure to polyethylene micro- and nanoplastics impairs umbilical blood flow but not fetal growth in pregnant mice
In a mouse study, pregnant mice exposed to polyethylene microplastics (the most common type of plastic) through drinking water showed a 43% increase in umbilical blood flow, suggesting abnormal placental function. While fetal growth was not affected, these changes raise concerns that microplastic exposure during pregnancy could lead to complications by disrupting how the placenta works.
Exposure of U.S. adults to microplastics from commonly-consumed proteins
Researchers tested 16 common protein foods sold in the U.S. for microplastic contamination, finding an average of 74 particles per serving, with highly processed products containing significantly more than minimally processed ones. Breaded shrimp had the most contamination (370 particles per serving) while chicken breast had the least. Based on typical American diets, the estimated annual exposure from these protein sources alone is about 11,000 microplastic particles per person.
Plastic pollution in the Arctic
This review describes how plastic pollution, including microplastics, has spread throughout the Arctic despite its remoteness, carried by ocean currents, rivers, and wind from lower latitudes. Plastics accumulate in Arctic ice, water, soil, and wildlife, and even if all plastic production stopped today, existing plastic would continue fragmenting into microplastics for decades. The contamination of this sensitive ecosystem is concerning because Arctic food webs, including fish consumed by humans, are already affected.
Microplastics may induce food dilution and endocrine disrupting effects in fathead minnows (Pimephales promelas), and decrease offspring quality
Fish exposed to microplastics for their entire lifecycle showed reduced growth and lower fat storage, likely because the plastic particles diluted the nutritional value of their food. Environmentally sourced microplastics (which carry absorbed pollutants) also disrupted hormones, delayed egg production, and caused birth defects in offspring -- even at low concentrations typical of real waterways. These findings suggest microplastics can harm fish populations through both nutritional and hormone-disrupting pathways.
Public awareness and perceptions of ocean plastic pollution and support for solutions in the United States
A nationally representative survey of nearly 2,000 U.S. adults found that plastic pollution was their top ocean concern, ahead of oil spills and climate change. About half of Americans had heard of microplastics, and most supported prevention measures and believed industry should take the lead in addressing the problem. However, concern focused more on impacts to marine wildlife than on direct human health risks, suggesting public awareness of the personal health dimension is still growing.
Microplastic exposure is associated with epigenomic effects in the model organism <i>Pimephales promelas</i> (fathead minnow)
Researchers exposed fathead minnows to microplastics and found changes in DNA methylation -- a chemical modification that controls which genes are turned on or off -- across multiple organs including the brain, liver, and gonads. These epigenetic changes are heritable, meaning microplastic exposure could affect not just the exposed fish but also future generations, raising concerns about long-term ecological and evolutionary impacts.
Human microplastic removal: what does the evidence tell us?
This commentary reviews the alarming finding that microplastics and nanoplastics have been detected in increasing levels in human brain tissue, particularly in patients with dementia. The authors discuss evidence-based strategies for reducing exposure and improving the body's ability to clear these particles, including dietary changes. While complete avoidance of microplastics is unrealistic, the review suggests practical steps people can take to lower their intake and potential health risks.
Sub-sampling strategies for analysis of small (<20 µm) microplastics in water
This study tested different methods for measuring very small microplastics (under 20 micrometers) in drinking water and found that analyzing too small a portion of a sample can lead to large errors when estimating total contamination. They determined that researchers need to analyze at least 6-8% of the total filter area to keep errors below 17%. Accurate measurement methods are critical because the smallest microplastics are the most abundant in drinking water and are the most likely to enter human tissues.
Microplastics and mental health: The role of ultra-processed foods
This paper proposes that microplastics in ultra-processed foods may partly explain why these foods are linked to worse mental health outcomes. With over 50% of calories in the U.S. coming from ultra-processed sources, and recent findings showing alarming microplastic levels in human brains, the authors suggest that food processing and packaging introduce microplastics that could affect brain function.
The Toxicity of Microplastics Explorer (ToMEx) 2.0
This paper describes an update to the Toxicity of Microplastics Explorer (ToMEx), a public database of microplastic toxicity studies used by researchers worldwide for risk assessment. The updated database roughly doubled in size, yet key trends held steady: smaller particles tend to be more toxic, and there is still a lack of dose-response data needed to set safe exposure limits. This tool is important because it helps scientists and regulators determine what levels of microplastic contamination might actually harm human health and ecosystems.
Engineering Organ-on-a-Chip Systems for Vascular Diseases
This review covers organ-on-a-chip technology, which creates miniature models of blood vessels on microchips to study diseases like atherosclerosis and blood clots. While not directly about microplastics, this technology is increasingly being used to study how microplastics and nanoplastics affect human blood vessels and organs in controlled laboratory settings. These advanced models could help researchers better understand the health risks of microplastic exposure without relying solely on animal studies.
Rethinking microplastics as a diverse contaminant suite
Researchers argue that the term microplastics oversimplifies what is actually a hugely diverse class of contaminants varying in size, shape, polymer type, and chemical additives. Treating all microplastics as a single pollutant leads to studies and regulations that may miss critical differences in how various particles behave and affect organisms. The study calls for a more nuanced approach that treats microplastics as a contaminant suite, similar to how pesticides or pharmaceuticals are categorized.
Quantitative assessment of visual microscopy as a tool for microplastic research: Recommendations for improving methods and reporting
Researchers conducted a multi-laboratory study across six countries to assess how accurately visual microscopy identifies microplastics in water samples. They found significant variability between laboratories in particle counts, size measurements, and material identification, with accuracy declining for smaller and transparent particles. The study recommends improved standardization and quality control measures to make microscopy a more reliable tool in microplastic research.
Maternal exposure to polystyrene nanoplastics impacts developmental milestones and brain structure in mouse offspring
Researchers exposed pregnant mice to polystyrene nanoplastics and studied the effects on their offspring's brain development. The study found that maternal nanoplastic exposure affected developmental milestones and brain structure in the young mice. The findings suggest that nanoplastic exposure during pregnancy may pose risks to fetal brain development, though more research is needed to understand the implications for humans.
Maternal exposure to polystyrene nanoplastics alters fetal brain metabolism in mice
When pregnant mice drank water containing polystyrene nanoplastics at low concentrations, their unborn pups showed significant changes in brain chemistry, including a 40% drop in GABA (a key brain chemical) and a 30% drop in glucose levels. These metabolic disruptions in the fetal brain could help explain the structural brain changes previously seen in pups born to nanoplastic-exposed mothers. This study raises concerns that nanoplastic exposure during pregnancy could affect fetal brain development in humans.
Automatic quantification and classification of microplastics in scanning electron micrographs via deep learning
Researchers developed a deep learning system that can automatically detect and classify microplastics in scanning electron microscope images, replacing the time-consuming process of manual analysis. The system achieved high accuracy in identifying different types and shapes of microplastic particles, even very small ones that are difficult to spot by eye. This automated approach could significantly speed up microplastic monitoring and pollution assessment efforts.
Microplastics and Anthropogenic Particles in Recreationally Caught Freshwater Fish from an Urbanized Region of the North American Great Lakes
Researchers found microplastics in recreationally caught freshwater fish from the Great Lakes region near Toronto, with higher particle counts in fish from urbanized Humber Bay. The study confirms that eating freshwater fish is a pathway for human microplastic exposure. While the health effects of ingesting these particles are still unclear, the findings support the need for broader geographic monitoring and inclusion in human health risk assessments.