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In 2015, several researchers from the University of Toronto dragged a brown catfish from Hamilton Harbor on the western end of Lake Ontario in a small boat. This summer, they reported that this fish broke the world record-it contains 915 synthetic particles, the most since record. 

"I have been studying microplastics," said Chelsea Rochman, a co-author of the study. "This is the study that surprised me." 

In the 6-year plastic pollution study led by Keenan Munno of the Rochman Laboratory at the University of Toronto and published in Conservation Biology this summer, the brown bullhead was one of them. Munno and her team found synthetic particles in each of them. Among the bull's heads, some of the smallest, called nanoplastics, have migrated from its digestive system to its skeletal muscles: fish fillets usually sold in grocery stores.

Experts say such findings highlight the need for additional research on nanoplastics and their impact on ecosystems and humans — and the need to take action to curb pollution in the Great Lakes.

Scientists have monitored microplastics for about 50 years. Small particles less than five millimeters long come from sources such as clothing and industrial processes. Freshwater systems are at higher risk of plastic contamination, partly because they are close to typical chemical plants and wastewater systems around cities and industrial areas. It is estimated that 22 million pounds of plastic waste enter the Great Lakes every year. When eaten by fish, the plastic does not decompose, but breaks down into smaller and smaller pieces. Nanoparticles accumulate throughout the life of the fish and are eventually consumed by organisms in the food chain. Nanoplastics can also absorb toxins and pollutants in waterways and spread them to the fish that eventually eat them.

Due to the advancement of microscope technology, international researchers have recently begun to study nano-scale plastics-0.0001 mm and below. Although they come from the same source as microplastics, nanoplastics have greater potential for harm because they can move more freely and bring a higher risk of cellular interference. 

The researchers say that because of their microscopic size and relatively large surface area, the interaction of nanoplastics with cells is different from that of microplastics. After ingestion, nanoplastics can penetrate the intestinal cell wall and enter the bloodstream from the digestive tract. They will not be excreted after eating, but will accumulate in important organs such as the intestines, liver, kidneys, and brain. In animal studies, the accumulation of synthetic particles in these key areas is related to inflammation, oxidative stress and immune response.

So what are the possible effects on people? There are data showing that microplastics and nanoplastics enhance the food chain through consumption. Although you may not have developed the habit of eating Great Lakes fish, they are a well-studied example of what is happening in bodies of water around the world-which means you may be eating seafood that has been exposed to some degree of nanoplastics.

Daniel Cyr first became interested in the toxicology of nanoplastics while conducting ecological research on fish in the St. Lawrence River. Earlier this summer, he received a $1 million grant from the Canadian National Science and Engineering Research Council to better understand the impact of nanoplastics on the human barrier system.

Cyr leads the laboratory of the Armand-Frappier Research Center in Montreal, hoping to analyze the potential of nanoplastics as a catalyst for worsening disease states. "[Nanoplastics] may have a broader and more subtle impact on the development of diseases and how these diseases differentiate, how they worsen or get better," he said. "These will have an impact on neuroscience, neurodegenerative diseases, female reproduction and the male reproductive tract."

The accumulation of nanoplastics in parts of the human body can cause tissue barriers to become inflamed, Cyr said, and may damage or change these barriers, thereby helping the body's immune response. For example, nanoplastics can interact with the blood-brain barrier and disrupt cell function. There are many neurodegenerative diseases and conditions associated with changes in this barrier, including Alzheimer's disease, multiple sclerosis, stroke, and epilepsy. 

Cyr is also studying the impact of inflammation on fertility: "If we look at infertile men, we always see that these barriers are changing. We know this is a key aspect of fertility, and we think nanoplastics will produce similar Influence."

He said his team is entering the toxicology research of nanoplastics at the "bottom level". Although large-scale research is still relatively new, experts say that in order to avoid these potentially harmful health effects, the use of nanoplastics must be stopped at the source. 

Christopher Hilkene, the CEO of the non-profit Pollution Probe, wants to do just that. The organization cooperates with the plastic waste production industry to prevent plastic from flowing into the Great Lakes. 

Agenda, November 16, 2021: Making the Great Lakes Smarter

Pollution Probe uses two types of filtration technologies: skimmers that act as floating dustbins and rainwater drainage and collection ponds (although they only filter plastics larger than 5 mm, they help stop plastics at the source when they are larger Fragments before they are broken down into nano-sized fragments). The organization analyzes plastics and works with manufacturers to build better production and disposal systems. "There is good momentum and action is happening," Silken said. 

But he said that Pollution Probe's efforts were not enough to slow down the accumulation of plastic. Need extensive public awareness and support. "Our existing technology cannot solve the problem by itself," he said. "The plan was never designed to do this."

At the same time, experts worry that this problem will continue to expand. "It's not just a waterway problem. It's a problem for anyone who eats aquatic species," Cyr said. "Humans are part of this ecosystem. Generally speaking, when we see the impact on wildlife, we also see the impact on humans. This has become a global phenomenon." 

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