Tag Archives: microplastics and food chain

What the Naked Eye Can’t See: Nanoplastics in Food and Sea

Smaller plastic particles are especially dangerous, because they are easily ingested and can enter organs and body fluids of organisms and thus propagate up the food chain. The fact that these particles are also co-contaminated with various chemicals and other pollutants makes accurate assessments of the effects and toxicity of plastic pollution challenging. A group of scientists led by the IAEA has recently published a comprehensive review on the effects on fish of ‘virgin’ micro- and nano-plastics – tiny plastic particles such as resin pellets used in plastics manufacturing. The review, published in the journal Environmental Science and Technology in March 2020, revealed that in 32% of all studies assessed, such virgin plastic particles were indeed affecting biological functions in fish, such as their behavior and neurological functions, as well as their metabolism, intestinal permeability and intestinal microbiome diversity.

Plastic particles below 5 mm in length are called microplastics. The smaller ones, with a size equal to or less than 100 nm (1/10 000 mm) are called nanoplastics. They are so tiny that one cannot see them with naked eye or even with an ordinary optical microscope.

According to the UN Environment Programme, 8 million tonnes of plastic end up the world’s oceans every year, often carried there by rivers. If the trend continues, by 2050 our oceans could contain more plastic than fish Microplastic particles are accidentally consumed by marine organisms, which are then consumed by predator fish. Nanoplastic particles are even more toxic to living organisms as they are more likely to be absorbed through the walls of digestive tracts and thereby transported into the tissues and organs. Consequently, such plastic particles can interfere with various physiological processes, from neurotransmission to oxidative stress and immunity levels of freshwater and marine organisms.

Jennet Orayeva, New Research on the Possible Effects of Micro-and Nano-plastics on Marine Animals

Genes that Atttack Plastic

A common fixture in refrigerators, furniture and footwear, polyurethane plastic is pretty much always in high demand. Humans worldwide cycle through millions of tons of the durable substance each year, sending the bulk of what’s not recycled to garbage dumps, where it leaks toxic chemicals into the environment as it very slowly breaks down. At least one of Earth’s organisms sees the stuff as a boon: a bacterial strain called Pseudomonas sp.TDA1. This polyurethane-munching microbe seems to thrive in waste dump sites. Studying the Pseudomonas strain and the chemical strategies it deploys could someday help researchers put a small dent in the world’s plastic problem, which has cumulatively saddled the planet with more than 8 billion tons of slow-degrading synthetic material.

Pseudomonas sp. TDA1 is one of only a few microbes known to be tolerant to polyurethane plastic’s typically toxic properties. What’s more, the bacteria doesn’t just withstand the plastic’s harsh ingredients: it uses some of them as a food source… But while the bacterium can metabolize a subset of the chemicals in polyurethane plastic, it doesn’t seem able to break down these products completely. In-depth studies of Pseudomonas sp. TDA1 will reveal the genes crucial to these plastic-attacking abilities. Understanding how these genes and their products work could help scientists engineer synthetic approaches to tackling plastic in the future.

Excerpts from Katherine J. Wu, Scientists Discover Plastic-Munching Microbe in Waste Site, SMITHSONIANMAG.COM, Mar. 31, 2020

Sunlight Can Make Plastics Disappear

Numerous international governmental agencies that steer policy assume that polystyrene, a sort of plastic  persists in the environment for millennia. 

Styrofoam Cup

In their research paper published in the Journal of  Environmental Science and Technology Letters, scientists show the  that polystyrene is completely photochemically oxidized to carbon dioxide and partially photochemically oxidized to dissolved organic carbon. Lifetimes of complete and partial photochemical oxidation are estimated to occur on centennial and decadal time scales, respectively. These lifetimes are orders of magnitude faster than biological respiration of polystyrene and thus challenge the prevailing assumption that polystyrene persists in the environment for millennia. 

Excerpt from Collin P. Ward et al, Sunlight Converts Polystyrene to Carbon Dioxide and Dissolved Organic Carbon, Journal of Environmental Science and Technology Letters, October 10, 2019

From Streets into Drains into Seas: Cigarette Butts

Cigarette butts, the most littered items in the world, are posing an intractable trash problem for regulators and tobacco companies: Throwing them on the ground is a firmly entrenched habit for many smokers.  Regulators are taking a tougher stance on cigarette filter pollution amid concerns about the environmental impact of single-use plastic. Butts for decades have been made from cellulose acetate, a form of plastic, which takes years to break down. Studies show that butts—which often wash from sidewalks into drains and then waterways—can be toxic to fish.

About 65% of cigarettes smoked in the U.S. are littered, according to Keep America Beautiful, a nonprofit whose cigarette litter prevention program is funded by the tobacco industry.  “That whole habit is so ingrained it becomes part of the ritual of taking the cigarette out of the pack, lighting it, smoking it, putting it on the ground,” said Christopher Proctor, chief scientific officer at British American Tobacco (BAT), whose cigarette brands include Kent, Newport and Camel. “Changing ingrained behavior is a really difficult thing to do.”

The European Union in May adopted new rules under which members must pass laws within two years requiring tobacco companies to fund the cleanup of filter litter as part of a broader crackdown on single-use plastics. A bill proposing banning filters has made its way through the California Senate and will be heard by the lower house next year.  In response, BAT and Japan Tobacco Inc. are testing biodegradable filters, while Philip Morris International Inc. is assessing the appetite for portable ashtrays. Companies also are tapping behavioral psychologists to understand what propels smokers to litter, hoping to forestall stricter regulation…

he World Health Organization says that when filters do break down they leach out some of the 7,000 chemicals contained in cigarettes, many of which are environmentally toxic.

Excerpts from Saabira Chaudhuri, The World’s Most Littered Item Comes Under Fire, WSJ, July 31, 2019

Melted Plastic on the Shores: Madeira Island

‘Plasticrusts’ are see on the surface of rocks in Madeira island, Portugal. Researchers say they may have identified a new kind of plastic pollution in the sea, and they’re calling it “plasticrust.” Scientists working on Madeira, a volcanic Portuguese island off northwest Africa, have found small patches of what look like melted plastic encrusted on rocks along the shoreline. 

Excerpts from Scientists on Madeira see new ‘plasticrust’ sea pollution, Associated Press,
June 25, 2019

Keep it in Your Backyard Please! The Revolution against Recyclable Plastics

There is no point collecting recyclable waste unless someone is willing to buy it and actually do the recycling. Until late 2017 China was the world’s biggest importer of scrap by far.  All this came to a halt when the Chinese government banned the import of all but the purest scrap material in 2017, killing a trade worth $24bn a year. Waste dealers in the rich world had to scramble to find new buyers. South-East Asia soon emerged as the pre-eminent destination for foreign waste. Unfortunately, the region’s recycling industry is much smaller than China’s; its processing plants were quickly overwhelmed. Plastics from America and Europe have piled up in landfills. Lots of toxic rubbish has simply been torched.

South-East Asian governments are not pleased. They have begun to ban or crimp imports themselves, abruptly diminishing a booming business. On May 28th, 2919 Yeo Bee Yin, Malaysia’s environment minister, complaining that “garbage [was] being traded under the pretext of recycling”, announced that her government would be sending back 3,000 tonnes of foreign plastic. Much of it was of poor quality, she noted, and hence unrecyclable.  Thailand plans to ban plastic-waste imports by 2021. Vietnam’s government has similar ideas. Kate O’Neill of the University of California, Berkeley, reckons these bans are motivated not only by environmental concerns but also by pride: Asia does not want to be the world’s dumping ground.  Rodrigo Duterte, the president of the Philippines, recently threatened to go to war with Canada if it did not take back a shipment of plastic scrap. Canada agreed to take it away…

Excerpts from South-East Asian countries are banning imports of waste for recycling, Economist, June 15, 2019

Can’t Eat This! MicroPlastics Carrying Bacteria

The hard surface of waterborne plastic provides an ideal environment for the formation of biofilm by opportunistic microbial colonisers, and could facilitate a novel means of dispersal for microorganisms across coastal and marine environments. Biofilms that colonise the so-called ‘plastisphere’ could also be a reservoir for faecal indicator organisms (FIOs), such as Escherichia coli, or pathogenic bacteria such as species of Vibrio.

Nurdles on bathing beach

A study published in March 2019 looks into five public bathing beaches and quantifies their colonisation by E. coli and Vibrio spp. Nurdles [i.e., microplastics] were heterogeneously distributed along the high tide mark at all five beaches, and each beach contained nurdles that were colonised by E. coli and Vibrio spp. Knowledge of E. coli colonisation and persistence on nurdles should now be used to inform coastal managers about the additional risks associated with plastic debris.

Abastract from Colonisation of plastic pellets (nurdles) by E. coli at public bathing beaches